WO2008069369A1

WO2008069369A1 - Horn array type antenna for dual linear polarization

Info

Publication number: WO2008069369A1
Application number: PCT/KR2007/001387
Authority: WO
Inventors: Seung Joon Im; Chang Wan Ryu; Jae Ho Ko
Original assignee: IDOIT CO Ltd
Current assignee: IDOIT CO Ltd
Priority date: 2006-12-08
Filing date: 2007-03-21
Publication date: 2008-06-12
Anticipated expiration: 2009-06-08

Abstract

A horn array antenna for dual linear polarization is provided, which includes one or more horns tapered along a propagation direction of an electric wave, to guide the electric wave, a first polarization guide to guide a first polarization separated from the electric wave provided by the horns, the first polarization guide having a horizontal width in the direction of the first polarization narrower than a height, and a second polarization guide to guide a second polarization which is provided from the horns and is at a substantially perpendicular relation with the first polarization, the second polarization guide having a horizontal width in the direction of the second polarization narrower than a height. As a result, a compact-sized antenna with improved performance, is provided.

Description

HORN ARRAY TYPE ANTENNA FOR DUAL LINEAR POLARIZATION

Technical Field

[1] The present invention relates to a horn array antenna for dual linear polarization; more particularly, to a horn array antenna for dual linear polarization for improving the antenna performance and reducing the size of antenna. Background Art

[2] Waves traveling higher than ultrahigh frequency have very short wavelengths and have characteristics similar to light. In order to effectively transmit or receive such waves, the technology has advanced itself to improve the directivity, applying optics theory or the theory that says a megaphone concentrates a sound wave. Such antennas, with enhanced directivity, are being manufactured in various shapes and configurations; they are known as horn antenna, parabola antenna, lens antenna, and slot antenna which have waveguides with holes formed thereon.

[3] Among these, the horn antenna is formed of a waveguide with one end formed in a horn shape and opened at both ends. The horn antenna radiates radio waves by vibrating one end of the waveguide and propagating radio waves along the waveguide so as to radiate to the air. As the impedance between the waveguide and the air is not matching, it reflects a part of the radio wave, which means that the entire energy is not radiated through air. Therefore, a horn antenna is designed to have its waveguide aperture to be gradually wider so that it matches the impedance between the air and the waveguide and allows it to maximally radiate energy through the aperture.

[4] Fig. 1 is the cross-sectional view of a horn in a horn antenna according to the related art.

[5] In Fig. 1, the horn antenna shows an exterior aperture 2 facing the air, and an interior aperture 3 at a side where the vibration starts. In such an antenna, the size of the exterior aperture 3 decides the performance of the antenna. The wider the size of the exterior aperture 3 is, the better the performance is provided. A ratio (S /S ) of the size of the exterior aperture 2 and that of the interior aperture 3 influences the performance of the antenna. In other words, the difference between the size of the exterior aperture 2, that of the interior aperture 3, and the gradient are important factors that decide the performance. So an antenna designed to perform better and to have a long horn usually has a larger size. Disclosure of Invention Technical Problem [6] The present trend of the development of communication technology is towards compactness.

[7] Accordingly, the demand persists that technology develop a method to reduce the size of an antenna while improving, or at least sustaining its performance.

[8] It is, therefore, an aspect of the present invention to provide a horn array antenna with dual linear polarization having an improved antenna performance and a small size. Technical Solution

[9] Other objects and advantages of the present invention can be understood by the following description, which become apparent on reference to the embodiments of the present invention. To those skilled in the art, it is obvious to which the present invention pertains and how the objects and advantages measure up as claimed, and by means of combinations.

[10] The present invention provides a horn array antenna for dual linear polarization, which includes one or more horns tapered along a propagation direction of an electric wave, to guide the electric wave, a first polarization guide to guide a first polarization separated from the electric wave provided by the horns, the first polarization guide having a horizontal width in the direction of the first polarization narrower than a height, and a second polarization guide to guide a second polarization which is provided from the horns and is at a substantially perpendicular relation with the first polarization, the second polarization guide having a horizontal width in the direction of the second polarization narrower than a height.

[11] The horns may each comprise a gradient to guide the electric wave, and including a ledge extended from an interior aperture facing the first polarization guide towards the center, and a polarization filtering unit to connect the gradient with the first polarization guide.

[12] One side of the polarization filtering unit may comprise a plurality of uneven parts such that the polarization filtering unit has a gradually decreasing width towards the first polarization guide.

[13] The polarization filtering unit may comprise a projection formed on a plane facing the uneven parts.

[14] A splitter may be further provided, which is connected to an upper part of each of the horns, to divide openings of the horns into a plurality of apertures. The splitter may comprise a plurality of ribs in lattice arrangement in which the ribs are spaced apart from each other by a predetermined distance in lateral and longitudinal directions.

[15] The first polarization guide may comprise a first through fourth guide tubes having openings in fluid connection with the polarization filtering unit, a first intermediate tube connecting the first and second guide tubes, and combining or separating the first polarization, a second intermediate tube connecting the third and fourth guide tubes, and combining or separating the first polarization, and a first mixing tube arranged between the first and second intermediate tubes, to connect the first and second intermediate tubes, and combine or separate the first polarization.

[16] The first through fourth guiding tubes may each compris a tube in substantially 'D' configuration, and a first inclined surface formed on a bent part of the tube to reflect the first polarization.

[17] A part of the first intermediate tube connected to the first and second guide tubes may have a width narrower than that of the first and second guide tubes, thereby having an uneven surface thereon, and a part of the second intermediate tube connected to the third and fourth guide tubes may have a width narrower than that of the third and fourth guide tubes, thereby having an uneven surface thereon.

[18] The horn array antenna according to an exemplary embodiment of the present invention may also comprise a first extension part in substantially square-pillar configuration, extended from a center of the first intermediate tube connecting the first and second guide tubes, inwards across the lengthwise direction of the first intermediate tube, and a second extension part in substantially square-pillar configuration, extended from a center of the second intermediate tube connecting the third and fourth guide tubes, inwards across the lengthwise direction of the second intermediate tube.

[19] The first mixing tube may comprise an uneven part formed on a part connected to the first and second intermediate tubes, the uneven part having a width narrower than that of the first and second intermediate tubes.

[20] The first mixing tube may comprise a third extension part in substantially square- pillar configuration, extended from a center of the first mixing tube connecting the first and second intermediate tubes, inwards across the lengthwise direction of the first mixing tube.

[21] A discharge tube may be extended from an end of the first mixing tube and be bent at least once.

[22] The second polarization guide may comprise first through fourth direction changing parts connected with the polarization filtering unit, to change the propagation direction of the second polarization, a third intermediate tube connecting the first and third direction changing parts, a fourth intermediate tube arranged in substantially symmetry with the third intermediate tube, and connecting the second and fourth direction changing parts, and a second mixing tube connecting the third and fourth intermediate tubes, and guiding the second polarization to enter or exit.

[23] The first through fourth direction changing parts may be upwardly open and connected with the polarization filtering unit, and each may comprise a projection formed on a bottom to change the propagation direction of the second polarization, and a reflective surface to reflect the second polarization towards the third and fourth intermediate tubes.

[24] The third intermediate tube may comprise an uneven surface formed on a part connected to the first and third direction changing parts, which has a narrower width than that of the first and third direction changing parts, and the fourth intermediate tube may comprise an uneven surface formed on a part connected to the second and fourth direction changing parts, which has a narrower width than that of the second and fourth direction changing parts.

[25] The third intermediate tube may comprise a fourth extension part in substantially square-pillar configuration extended from a center connecting the first and third direction changing parts, inwards across the lengthwise direction of the third intermediate tube, and the fourth intermediate tube may comprise a fifth extension part in substantially square -pillar configuration extended from a center connecting the second and fourth direction changing parts, inwards across the lengthwise direction of the third intermediate tube.

[26] The second mixing tube may comprise an uneven surface formed on a part connected with the third and fourth intermediate tubes, as the width becomes narrower than that of the third and fourth intermediate tubes.

[27] The second mixing tube may comprise a sixth extension part in substantially square-pillar configuration, extended from a center connected with the third and fourth intermediate tubes, inwards across the lengthwise direction of the second mixing tube.

[28] The present invention also provides a horn array antenna for dual linear polarization, which comprises a first layer to form a splitter which comprises a plurality of ribs in lattice arrangement, in which the ribs are spaced apart from each other in lateral and longitudinal directions, a second layer on which a plurality of horns are formed to guide an electric wave to enter or exit, a third layer on which a first polarization guide is formed to guide the first polarization and is connected with the horns, a fifth layer on which a second polarization guide is formed in substantially parallel relation with the first polarization guide to guide a second polarization which has a propagation direction substantially perpendicular to that of the first polarization and is connected with the horns, and a fourth layer arranged between the third and fifth layers, to form a lower part of the first polarization guide and to form an upper part of the second polarization guide.

[29] The horns on the second layer may each comprise a gradient tapered along the propagation direction of the electric wave, and a ledge projected from an interior aperture formed at an end of the gradient of a narrower width, towards a center.

[30] The first polarization guide formed by the third and fourth layers may comprise a first through fourth guide tubes each comprising an opening connected with the polarization filtering unit, a first intermediate tube connecting the first and second guide tubes, and combining or separating the first polarization, a second intermediate tube connecting the third and fourth guide tubes, and combining or separating the first polarization, and a first mixing tube arranged between the first and second intermediate tubes, to connect the first and second intermediate tubes, and combine or separate the first polarization.

[31] The third and fourth layers may comprise one or more symmetric distribution tubes each comprising a linear tube which is connected with the same number of the first polarization guides at opposite ends, and a branch tube extended from the middle part of the linear tube, and one or more asymmetric distribution tubes each comprising a linear tube connected with the first polarization guides in the ratio of l:n at opposite ends, and a branch tube extended from the middle part of the linear tube, wherein the symmetric distribution tubes are connected with the same number of the other symmetric distribution tubes at opposite ends, and the asymmetric distribution tubes are connected with the different number of the symmetric distribution tubes or of the other asymmetric distribution tubes.

[32] The opposite ends of the linear tube of each of the symmetric distribution tubes may be formed narrower than the width of the connected tube.

[33] One end of the linear tube of each of the asymmetric distribution tubes may comprise at least one uneven surface which has a width gradually decreasing towards the other end along the lengthwise direction.

[34] An end of the branch tube of each of the asymmetric distribution tubes may comprise at least one uneven surface which has a width gradually decreasing towards the end.

[35] The fourth and fifth layers may comprise a first polarization main aperture connected with an end of the branch tube of the asymmetric distribution tubes, through which the first polarization enters or exits.

[36] The second polarization guide formed on the lower side of the fourth layer and on the upper side of the fifth layer may comprise a first through fourth direction changing parts connected with the polarization filtering unit, to change the propagation direction of the second polarization, a third intermediate tube to connect the first and third direction changing parts, a fourth intermediate tube arranged in substantially symmetry with the third intermediate tube, to connect the second and fourth direction changing parts, and a second mixing tube to connect the third and fourth intermediate tubes, and guide the second polarization to enter or exit.

[37] The fourth and fifth layers may comprise one or more symmetric distribution tubes each comprising a linear tube which is connected with the same number of the second polarization guides at opposite ends, and a branch tube extended from the middle part of the linear tube, and one or more asymmetric distribution tubes each comprising a linear tube connected with the second polarization guides in the ratio of 1 :n at opposite ends, and a branch tube extended from the middle part of the linear tube, wherein the symmetric distribution tubes are connected with the same number of the other symmetric distribution tubes at opposite ends, and the asymmetric distribution tubes are connected with the different number of the symmetric distribution tubes or of the other asymmetric distribution tubes.

[38] The opposite ends of the linear tube of each of the symmetric distribution tubes may be formed narrower than the width of the connected tube.

[39] One end of the linear tube of each of the asymmetric distribution tubes may comprise at least one uneven surface which has a width gradually decreasing towards the other end along the lengthwise direction.

[40] An end of the branch tube of each of the asymmetric distribution tubes may comprise at least one uneven surface which has a width gradually decreasing towards the end.

[41] The fifth layer may comprise a second polarization main aperture connected with an end of the branch tube of the asymmetric distribution tubes, through which the second polarization enters or exits.

[42] The fifth layer may comprise a projection formed on a bottom of each of the first through fourth direction changing parts to change the propagation direction of the second polarization, and a reflective surface to reflect the second polarization towards the third and fourth intermediate tubes.

Advantageous Effects

[43] According to the present invention, the performance of the antenna can be improved while the size of the antenna is reduced. Brief Description of the Drawings

[44] The above and other objects and features of the present invention will become apparent from the following description of the preferred embodiments given in conjunction with the accompanying drawings, in which: [45] Fig. 1 is the cross-sectional view of a horn in a horn antenna according to the related art; [46] Fig. 2 is the upper view of a horn array antenna for dual linear polarization according to an embodiment of the present invention; [47] Figs. 3 and 4 are bottom perspective views of the horn array antenna for dual linear polarization shown in Fig. 2; [48] Fig. 5 is a front view of a horn of the horn array antenna for dual linear polarization shown in Fig. 2;

[49] Fig. 6 is a perspective view of the horn shown in Fig. 5;

[50] Fig. 7 is a transparent perspective view of the horn shown in Fig. 5;

[51] Fig. 8 is a transparent side view of the horn shown in Fig. 5;

[52] Fig. 9 is a partially-cut perspective view of the horn shown in Fig. 5;

[53] Fig. 10 is a partially-cut perspective view of a horn according to another embodiment of the present invention; [54] Fig. 11 is a schematic side cross-section view of a horn according to an embodiment of the present invention; [55] Fig. 12 is a schematic side cross-section view of a horn having the same length and the same size of an exterior aperture as the horn shown in Fig. 11 ; [56] Fig. 13 is a schematic side cross-section view of a horn having the same performance as the horn shown in Fig. 11 ;

[57] Fig. 14 is a graphical representation of S 11 parameter of the horn shown in Fig. 11 ;

[58] Fig. 15 is a graphical representation of Sl 1 parameter of the horn shown in Fig. 12;

[59] Fig. 16 is a graphical representation of Sl 1 parameter of the horn shown in Fig. 13;

[60] Fig. 17 is an extended perspective view of a polarization filtering unit;

[61] Fig. 18 is a graphical representation of S 11 parameter of port 1 with respect to the first polarization of the polarization filtering unit shown in Fig. 17; [62] Fig. 19 is a graphical representation of S21 parameter between port 1 and port 2 with respect to the first polarization of the polarization filtering unit shown in Fig. 17; [63] Fig. 20 is a graphical representation of S31 parameter between port 1 and port 3 with respect to the first polarization of the polarization filtering unit shown in Fig. 17; [64] Fig. 21 is a graphical representation of S 11 parameter of port 1 with respect to the second polarization of the polarization filtering unit shown in Fig. 17; [65] Fig. 22 is a graphical representation of S21 parameter between port 1 and port 2 with respect to the second polarization of the polarization filtering unit shown in Fig.

17; [66] Fig. 23 is a graphical representation of S31 parameter between port 1 and port 3 with respect to the second polarization of the polarization filtering unit shown in Fig.

17; [67] Fig. 24 is a perspective view of a first polarization guide being connected with a second polarization guide;

[68] Fig. 25 is a perspective view of the first polarization guide shown in Fig. 24;

[69] Fig. 26 is a upper view of the first polarization guide shown in Fig. 24;

[70] Fig. 27 is a perspective view of the first polarization guide from which the polarization filtering unit is removed; [71] Fig. 28 is a transparent perspective view of an intermediate tube; [72] Fig. 29 is a transparent perspective view of a second polarization guide;

[73] Fig. 30 is a perspective view of the second polarization guide shown in Fig. 29;

[74] Fig. 31 is a upper view of the second polarization guide shown in Fig. 29;

[75] Fig. 32 is a transparent perspective view of a T-type distribution tube according to another embodiment of the present invention; [76] Fig. 33 is a transparent perspective view of a T-type distribution tube according to yet another embodiment of the present invention; [77] Fig. 34 is a transparent perspective view of a branching tube of a T-type distribution tube according to another embodiment of the present invention; [78] Fig. 35 is an exploded perspective view of respective layers of a horn array antenna for dual linear polarization according to the present invention; [79] Fig. 36 is a upper view of the first layer shown in Fig. 35;

[80] Fig. 37 is a perspective view of the first layer shown in Fig. 35;

[81] Fig. 38 is a perspective view of the second layer shown in Fig. 35;

[82] Fig. 39 is a upper view of the second layer shown in Fig. 35;

[83] Fig. 40 is a bottom view of the second layer shown in Fig. 35;

[84] Fig. 41 is a perspective view of the third layer shown in Fig. 35;

[85] Fig. 42 is a upper view of the third layer shown in Fig. 35;

[86] Fig. 43 is a bottom view of the third layer shown in Fig. 35;

[87] Fig. 44 is a perspective view of the fourth layer shown in Fig. 35;

[88] Fig. 45 is a upper view of the fourth layer shown in Fig. 35;

[89] Fig. 46 is a bottom view of the fourth layer shown in Fig. 35;

[90] Fig. 47 is a perspective view of the fifth layer shown in Fig. 35;

[91] Fig. 48 is a upper view of the fifth layer shown in Fig. 35;

[92] Fig. 49 is a perspective view illustrating a horn array antenna in use according to the present invention;

[93] Fig. 50 is a upper view of the horn array antenna shown in Fig. 49;

[94] Fig. 51 is a perspective view of the first layer of the horn array antenna shown in

Fig. 49;

[95] Fig. 52 is a perspective view of the second layer shown in Fig. 49;

[96] Fig. 53 is a upper perspective view of the third layer of the horn array antenna shown in Fig. 49;

[97] Fig. 54 is a bottom perspective view of the third layer shown in Fig. 49;

[98] Fig. 55 is a upper perspective view of the fourth layer shown in Fig. 49;

[99] Fig. 56 is a transparent perspective view of first through sixth asymmetric distribution tubes; [100] Fig. 57 is a bottom perspective view of the fourth layer of the horn array antenna shown in Fig. 49; [101] Fig. 58 is a upper perspective view of the fifth layer shown in Fig. 49; and

[102] Fig. 59 is a bottom perspective view of the fifth layer shown in Fig. 49.

Best Mode for Carrying Out the Invention

[103] Other objects and aspects of the invention become apparent from the following description of the embodiments referring to the drawings, set hereinafter.

[104] A horn array antenna for dual linear polarization according to an embodiment of the present invention performs a function of either receiving or transmitting radio waves. For convenience, the constituent elements of the horn array antenna for dual linear polarization will be described based on a radio wave receiving function at first. Afterward, transmitting function of the horn array antenna will be described.

[105] According to one embodiment of the present invention, a first polarization denotes a horizontal polarization ¹H', parallel to the equator of earth, and a second polarization denotes a vertical polarization 'V, which is perpendicular to the equator of earth.

[106] Fig. 2 is the upper view of a horn array antenna for dual linear polarization according to an embodiment of the present invention, and Figs. 3 and 4 are bottom perspective views of the horn array antenna for dual linear polarization shown in Fig. 2.

[107] The horn array antenna for dual linear polarization 1 includes a plurality of horns 10 to receive electric waves, lattice type splitters 70 mounted to the upper parts of the horns 10 to divide the electric waves, first polarization guides 530 to guide the first polarizations of the electric waves received through the horns 10, and second polarization guides 550 to guide the second polarizations of the electric waves received through the horns 10.

[108] Four horns 10 are open to the air, and the first polarization guides 530 are formed under the horns 510. The second polarization guides 550 are formed under the first polarization guides 530. The horns 10, and the first and second polarization guides 530, 550 are the spaces where electric wave travels, and the configurations of respective layers to form the horns 10 and the first and second polarization guides 530, 550 will be explained below.

[109] Four horns 10, and the first and second polarization guides 530, 550 form one antenna unit. Hereinafter, the horn array antenna for dual linear polarization 1 is described based on an antenna unit. The four horns 10 will be referred to as first, second, third and fourth horns below.

[110] Fig. 5 is a front view of a horn of the horn array antenna for dual linear polarization shown in Fig. 2, Fig. 6 is a perspective view of the horn shown in Fig. 5, Fig. 7 is a transparent perspective view of the horn shown in Fig. 5, Fig. 8 is a transparent side view of the horn shown in Fig. 5, and Fig. 9 is a partially-cut perspective view of the horn shown in Fig. 5.

[I l l] As explained above, one antenna unit includes four horns 10, and exterior aperture of each of the horns 10 is divided into four openings by the lattice type splitter 70, so one antenna unit includes 16 openings.

[112] The splitter 70 is mounted to the upper part of the horns 10, and includes a plurality of ribs 75 in a lattice arrangement, and each of the horns 10 includes ribs 75 of the splitter 70 in columns and rows at the exterior aperture. Accordingly, the exterior aperture of each horn 10 is divided into four smaller openings. By dividing the exterior apertures of the horns 10 by use of the ribs 75, the antenna can have reduced side lobes and improved radiation efficiency.

[113] The horns 10 guide electric waves in a manner such that first and second polarization waves, in substantially perpendicular relation with each other, are received on the surface of incidence. Each of the horns 10 includes a gradient 15 formed a quadrangular pyramid, and a polarization filtering unit 20 formed on an end of the gradient 15.

[114] The gradient 15 is tapered along the propagation direction of electric waves, and both ends are open along the propagation direction of the electric waves. Among the open ends of the gradient 15, an end facing the splitter 70 is an exterior aperture, and a substantially rectangular end formed at an inner end of the gradient 15 with a narrower width is an interior aperture. The interior aperture includes a ledge 17 protruding from a circumference of the interior aperture 15 towards the center. That is, the ledge 17 protrudes to have a predetermined width along the circumference of the interior aperture. A second ledge 19 is formed on a side of the polarization filtering unit 20, and contributes to providing an improved SI l parameter of vertical polarization.

[115] As shown in Figs. 5 through 9, the ledge 17 of the gradient 15 protrudes to have a predetermined width along the interior aperture, thereby providing a substantially rectangular profile of the interior aperture.

[116] Fig. 10 is a partially-cut perspective view of a horn according to another embodiment of the present invention.

[117] Referring to Fig. 10, the horn 10 according to an embodiment of the present invention includes a pair of ledges 18a and 18b disposed on a surface of the gradient 15. The performance of the horn antenna may be maintained or even improved by forming at least one ledge 18a, 18b, and the horn antenna can have a reduced height.

[118] Although the particular example of the embodiment of the present invention employs two ledges 18a, 18b, it should be understood that the number of ledges 18a, 18b, or number of openings divided by the splitter 70, may be changed.

[119] The horn array antenna 1 for dual linear polarization shown in Fig. 2 employs the horns exemplified with reference to Fig. 9, but other types of horns, such as the ones exemplified with reference to Fig. 10, or horns with different configurations and sizes, can be employed.

[120] Fig. 11 is a schematic side cross-section view of a horn according to an embodiment of the present invention, Fig. 12 is a schematic side cross-section view of a horn having the same length and the same size of an exterior aperture as the horn shown in Fig. 11, and Fig. 13 is a schematic side cross-section view of a horn having the same performance as the horn shown in Fig. 11.

[121] The length of the horn 110 shown in Fig. 12 is about 61.0 mm, and the length of the horn 210 shown in Fig. 13 is about 71.0 mm. The widths of the exterior apertures of each horn 10, 110, 210 are uniform, about 48.0 mm. Table 1 shows the results of comparing antenna gains of three horns 10, 110, 210 under the conditions of the center frequency of 11.7GHz; the upper sideband of 12.75GHz, the lower sideband of 10.7GH among a satellite broadcasting band KU band from 10.7GHz to 12.75GHz.

[122] Table 1

[123] As shown in Table 1, the horn 10 according to an exemplary embodiment of the present embodiment and the horn 210 shown in Fig. 13, which is designed longer than the horn 10 according to the exemplary embodiment of the present invention approximately by 10.0mm, provide the same performance at all frequency bands. However, the horn 110 shown in Fig. 12, which has the same-sized exterior apertures and the same length as the horn 10 according to the exemplary embodiment of the present invention, provides a smaller antenna gain than the horn 10 according to the exemplary embodiment of the present invention as much as about 0.5dBi at 10.7 GHz band, OJdBi at 11.7 GHz band, and 0.5dBi at 12.7GHz band. In case of IdBi of the antenna gain difference, the antenna performance will improve at 33% in general. Therefore, the performance of the horn 10 according to the exemplary embodiment of the present invention is improved at about 18% compared with that of the same-sized related art horn. The height also is reduced by 10 mm compared with the horn 210 shown in Fig. 13 having the same performance, which indicates that the compacter antenna can be provided according to the present invention.

[124] Fig. 14 is a graphical representation of Sl 1 parameter of the horn shown in Fig. 11, Fig. 15 is a graphical representation of Sl 1 parameter of the horn shown in Fig. 12, and Fig. 16 is a graphical representation of Sl 1 parameter of the horn shown in Fig. 13.

[125] The parameter SI l shows a tendency that an electric wave returns to an antenna after the electric wave is radiated from the antenna. The lower the parameter SI l is, the better the performance is. In general, the parameter Sl 1 is allowable when the parameter Sl 1 is lower than -10 dB.

[126] As the horns 10 according to the present embodiment provide the parameter SI l lower than -4OdB at about 11.6GHz, the parameter Sl 1 of the horns 10 is in good c ondition. As such, the horns 10 provide the good parameter SI l compared with the horns 110 shown in Fig. 12, which provide about -5OdB of parameter SI l at 12.2GHz, or the horns 210 shown in Fig. 13 providing about -3OdB of Sl 1 parameter.

[127] As shown, by forming the ledge 17 at the interior aperture of the gradient 15, the length of the gradient 15 can be shortened, without affecting the widths of the interior and exterior apertures, and without compromising the gain of the antenna 1.

[128] Fig. 17 is an extended perspective view of a polarization filtering unit.

[129] Referring to Figs. 7, 9 and 17, the polarization filtering unit 20 is connected to the interior aperture of the gradient 15, and there are four polarization filter units 20 mounted for each antenna unit. Each of the polarization filtering unit 20 passes only a predetermined polarization. For example, the polarization filter unit 20 passes only a second polarization, but does not pass a first polarization. As the first polarization cannot pass the polarization filtering unit 20, it is guided to the first polarization guide 530. The second polarization passes an uneven surface formed on the polarization filtering unit 20, and guided to the second polarization guide 550.

[130] The polarization filtering unit 20 includes a first port connected to the horn 10, a second port connected to the first polarization guide 530, and a third port connected to the second polarization guide 550.

[131] The polarization filtering unit 20 extends from the interior aperture to the second polarization guide 550, and has an uneven surface with a plurality of steps 25 extended from the interior aperture. The uneven surface having the steps 25 causes the width of the polarization filtering unit 20 to be gradually decreased. The uneven surface having the steps 25 separates the first and the second polarization passing the polarization- filtering unit 20, thereby providing the first polarization to the first polarization guide 530 and the second to the second polarization guide 550. The first polarization, with an electric field directivity identical to the wider width of the polarization filtering unit 20, is given to the first polarization guide 530, and the second polarization, with an electric field directivity identical to the narrow width of the polarization filtering unit 20, is given to the second polarization guide 550 along the polarization filtering unit 20. The number, the size, and the length of the steps 25 may change according to the frequency of the second polarization guided along the second polarization guide 550. [132] Meanwhile, a passage 27, connected to the first polarization guide 530, is formed at the central area of the steps 25, and gradually widens toward the first polarization guide 530 along the direction of length. The width, the length, and the height of the steps forming the passage 27, may change according to the frequency of the first polarization provided to the first polarization guide 530.

[133] Figs. 18 through 20 are graphical representation of S parameter of the first polarization of the polarization filtering unit shown in Fig. 17, in which Fig. 18 illustrates SI l parameter of port 1, Fig. 19 illustrates S21 parameter between port 1 and port 2, and Fig. 20 illustrates S31 parameter between port 1 and port 3.

[134] The first polarization, according to the graphs, has about -24 dB of the SI l parameter at 10.7GHz, and has the high S21 parameter identical to the Sl 1 at the same frequency band. That is, according to the graphs, the first polarization inputs through the port 1, and outputs through the port 2.

[135] Figs. 21 through 23 are graphical representations of the second polarization of the polarization filtering unit shown in Fig. 17, in which Fig. 21 illustrates SI l parameter of port 1, Fig. 22 illustrates S21 parameter between port 1 and port 2, and Fig. 23 illustrates S31 parameter between port 1 and port 3.

[136] As graphs show, the second polarization has the SI l parameter gradually decreasing as the frequency band increases, and that the SI l parameter of the second polarization lessens to more than -10 dB throughout the whole region of the satellite broadcasting. As the frequency band increases, the S31 parameter increases. That is, the second polarization inputs from the port 1 and outputs through the port 3.

[137] Fig. 24 is a perspective view of a first polarization guide being connected with a second polarization guide, Fig. 25 is a perspective view of the first polarization guide shown in Fig. 24, Fig. 26 is a upper view of the first polarization guide shown in Fig. 24, and Fig. 27 is a perspective view of the first polarization guide from which the polarization filtering unit is removed.

[138] The first polarization guide 530 guides the first polarization inputted through the four horns 10, and outputs the first polarization. The first polarization guide 530 has four apertures A, B, C, and D connected to the four polarization filtering units 20, in which, aperture A is connected to the first horn, aperture B to the second horn, aperture C to the third horn, and aperture D to the fourth horn.

[139] The first polarization guide 530 includes a first through fourth guide tubes 531, 532,

533, 534 extended from the apertures A, B, C, D, respectively, a first intermediate tube 535 connecting the first guide tube 531 with the second guide tube 532, a second intermediate tube 540 connecting the third guide tube 533 with the fourth guide tube

534, a first mixing tube 545 connecting the first intermediate tube 535 with the second intermediate tube 540, and a discharge tube 548 extended from the first mixing tube 545.

[140] The first through fourth guide tubes 531, 532, 533, 534 are connected with the polarization filtering units 20, and receive the first polarization through the respective apertures A, B, C, D. The first guide tube 531 is connected with the aperture A, the second guide tube 532 is connected with the aperture B, the third guide tube 533 is connected with the aperture C, and the fourth guide tube 534 is connected with the aperture D. The apertures A, B, C, D are open to the same directions, and the first and third guide tubes 531, 533, and the second and fourth guide tubes 532, 534 are in substantially parallel relation with each other, respectively.

[141] Each of the first through fourth guide tubes 531, 532, 533, 534 is in substantially 'D' configuration, and the first and second guide tubes 531, 532 are substantially symmetrical with reference to the first intermediate tube 535, and the third and fourth guide tubes 533, 534 are substantially symmetrical with reference to the second intermediate tube 540. As the first and second guide tubes 531, 532, and the third and fourth guide tubes 533, 534 are symmetrically formed, the first polarization traveling along the first guide tube 531 and the first polarization traveling along the second guide tube 532 have the same phase when the first polarization reaches the first intermediate tube 535, and the first polarization traveling along the third guide tube 533 and the first polarization traveling along the fourth guide tube 534 have the same phase when the first polarization reaches the second intermediate tube 540. Accordingly, offset, or distortion of the first polarization due to phase difference can be avoided, when the first polarizations from the first and second guide tubes 531, 532 meet at the first intermediate tube 535, and when the first polarization from the third and fourth guide tubes 533, 534 meet at the second intermediate tube 540.

[142] The first through fourth guide tubes 531, 532, 533, 534 each include a first gradient

549a formed on a bent part, to alter the direction of the first polarization perpendicularly. The first polarization is entered through the apertures A through D, reflected against the first gradients 549a of the guide tubes 531, 532, 533, 534 in a substantially perpendicular direction, and propagated towards the first intermediate tube 535 or the second intermediate tube 540. That is, the first polarization entering into the first and second guide tubes 531, 532 travels along the first and second guide tubes 531, 532, is reflected against the first gradients 549a, and headed toward the first intermediate tube 535. The first polarization entering into the third and fourth guide tubes 533, 534 travels along the third and fourth guide tubes 533, 534, is reflected against the first gradients 549a, and headed toward the second intermediate tube 540.

[143] Fig. 28 is a transparent perspective view of an intermediate tube.

[144] Referring to Figs. 27 and 28, the first and second intermediate tubes 535, 540 are in substantially T configuration, in the same configuration as that of the intermediate tube shown in Fig. 28. The first intermediate tube 535 is connected with the first guide tube 531, the second guide tube 532, and the first mixing tube 545, respectively, and the second intermediate tube 540 is connected with the third guide tube 533, the fourth guide tube 534 and the first mixing tube 545, respectively. The first intermediate tube 535 combines the first polarizations from the first and second guide tubes 531, 532 and provides the first mixing tube 545 with the mixed first polarization, and the second intermediate tube 540 combines the first polarizations from the third and fourth guide tubes 533, 534 and provides the first mixing tube 545 with the mixed first polarization. The first and second intermediate tubes 535, 540 are substantially symmetrical with reference to the first mixing tube 545.

[145] The parts of the first and second intermediate tubes 535, 540, which are connected with the first through fourth guide tubes 531, 532, 533, 534, have a lateral width narrower than that of the first through fourth guide tubes 531, 532, 533, 534, along the propagation direction of the first polarization. Accordingly, an uneven surface 537 is formed on a place where the second intermediate tube 540 meets the third and fourth guide tubes 533, 534, and another uneven surface 542 is formed on a place where the second intermediate tube 540 meets the third and fourth guide tubes 533, 534. The uneven surfaces 537, 542 are formed on opposite sides in the lateral width direction. As illustrated in Fig. 28, only one uneven surface 537, 542 may be formed along the length of the first intermediate tube 535 and the second intermediate tube 540. Alternatively, a plurality of uneven surfaces 537, 542 may be provided.

[146] A first extension part 536 is in a substantially square pillar configuration, and is extended from a part of the first intermediate tube 535 where the first polarizations from the first and second guide tubes 531, 532 meet, towards the first mixing tube 545. Likewise, a second extension part 541 is extended from a part of the second intermediate tube 540 where the first polarizations from the third and fourth guide tubes 533, 534 meet, towards the first mixing tube 545. The first and second extension parts 536, 541 are also extended vertically, to connect the top and bottom surfaces of the first and second intermediate tubes 535, 540. The first polarizations provided from the first and second guide tubes 531, 532 change the electric field directivity by about 90 degrees by the first extension part 536, and the first polarizations with the changed directivity are mixed with each other and propagated towards the first mixing tube 545. Likewise, the first polarizations provided from the third and fourth guide tubes 533, 534 change the electric field directivity by about 90 degrees by the second extension part 541, and the first polarizations with the changed directivity are mixed with each other and propagated toward the first mixing tube 545.

[147] The first mixing tube 545 is formed in substantially 'T' configuration, and combines the first polarizations provided from the first and second intermediate tubes 535, 540 with each other, and provides the discharge tube 548 with the mixed first polarization. The connecting areas between the first and second intermediate tubes 535, 540 and the first mixing tube 545 have a narrower lateral width than that of the first and second intermediate tubes 535, 540 in the propagation direction of the first polarization, and accordingly, uneven surfaces 547 are formed on the opposite sides in the lateral width direction, on the connecting areas between the first mixing tube 545 and the first and second intermediate tubes 535, 540. A third extension part 546 is extended from a part of the first mixing tube 545 where the first polarization from the first intermediate tube 535 meets the first polarization from the second intermediate tube 540, inwards the first mixing tube 545. The third extension part 546 is formed in a substantially square solid configuration, and is also extended vertically from the top toward the bottom surface of the first mixing tube 545.

[148] The first polarizations from the first and second intermediate tubes 535, 540 change electric field directivities by about 90 degrees when the first polarization meet the third extension part 546, and the first polarizations with the changed directivities are mixed with each other, and propagated towards the discharge tube 548.

[149] The discharge tube 548 is formed in a substantially 'D' configuration, in which the discharge tube 548 is bent and extends from an end of the first mixing tube 545 and bent again and extends outwards. A second gradient 549b is formed on a connecting area between the first mixing tube 545 and the discharge tube 548, to reflect the first polarization of the first mixing tube 545 to a substantially perpendicular direction, and a third gradient 549c is formed on the bent area of the discharge tube 548 to change once again the direction of the first polarization which has changed the direction at the second gradient 549b. The first polarization propagates along the discharge tube 548 and starts to be discharged at the antenna units. The first polarization, being discharged at one antenna unit, is mixed with the first polarization discharged from another antenna unit, and the mixture of the first polarization is discharged out. The movement of the first polarization after being discharged at the antenna units, will be explained in detail below.

[150] The center frequency of the first polarizations, which enter into the first and second intermediate tubes 535, 540 and the first mixing tube 545, is determined according to the widths of the first through third extension parts 536, 541, 546. Accordingly, the center frequency of the first polarization entering into the first mixing tube 545 may be shifted, by adjusting the widths of the first through third extension parts 536, 541, 546.

[151] The first mixing tube 545 may converge the first polarizations from the first and second intermediate tubes 535, 540 towards the discharge tube 548, or split the first polarization provided through the discharge tube 548, into the first and second intermediate tubes 535, 540. That is, the first mixing tube 545 may operate as a function block which combines two types of waves into one, or divide one wave into two waves. The first mixing tube 545 may be attached to an appropriate antenna to be used.

[152] Fig. 29 is a transparent perspective view of a second polarization guide, Fig. 30 is a perspective view of the second polarization guide shown in Fig. 29, and Fig. 31 is a upper view of the second polarization guide shown in Fig. 29.

[153] The second polarization guide 550 is in substantially parallel relation with the first polarization guide 530. The second polarization guide 550 receives a second polarization from the polarization filtering unit 20 and guides the second polarization.

[154] The second polarization guide 550 includes first through fourth direction changing parts 551, 552, 553, 554 which change the propagation direction of the second polarization transmitted from the polarization filtering unit 20, a third intermediate tube 555 which connects the first and second direction changing parts 551, 553, a fourth intermediate tube 560 which connects the second and fourth direction changing parts 552, 554, and a second mixing tube 565 which combines the second polarizations provided from the third and fourth intermediate tubes 555, 560.

[155] The first through fourth direction changing parts 551, 552, 553, 554 are each formed in substantially ¹T' configuration with edge open upwards, and connected with the polarization filtering unit 20. The first through fourth direction changing parts 551, 552, 553, 554 each have a projection part 568 and a reflective surface 569. The projection parts 568 are formed on ends of the direction changing parts 551, 552, 553, 554 which face the polarization filtering unit 20. Accordingly, the projection parts 568 are each extended from the bottoms of the direction changing parts 551, 552, 553, 554, to a substantially rectangular configuration in a substantially parallel relation with the length of the linear tubes of the third and fourth intermediate tubes 555, 560. The second polarization, having the electric field directivity along the narrower width of the polarization filtering unit 20, changes its direction as it collides against the projection parts 568. The reflective surfaces 569 are formed on the upper which face the projection parts 568, with a predetermined inclination angle. Accordingly, the second polarization, which changes its direction at the projection part 568, is reflected against the reflective surface 569 and provided to the third intermediate tube 555.

[156] The first and second direction changing parts 551, 552 are formed in a substantially parallel relation with each other such that the reflective surfaces 569 and the projection parts 568 correspond in position with each other, and the third and fourth direction changing parts 553, 554 are also formed in a substantially parallel relation with each other such that the reflective surfaces 569 and the projection parts 568 correspond in position with each other. The reflective surfaces 569 of the first and third direction changing parts 551, 553 are in substantially symmetry with each other, and the reflective surfaces 569 of the second and fourth direction changing parts 552, 554 are also in substantially symmetry with each other.

[157] Like the first and second intermediate tubes 535, 540, the third and fourth intermediate tubes 555, 560 are formed in substantially 'T' configuration. The third intermediate tube 555 is connected with the first direction changing part 551, the third direction changing part 553, and the second mixing tube 565, and the fourth intermediate tube 560 is connected with the second direction changing part 552, the fourth direction changing part 554 and the second mixing tube 565. The third intermediate tube 555 combines the second polarizations, which change the direction at the first and third direction changing parts 551, 553, and provides the mixed second polarization to the second mixing tube 565, and the fourth intermediate tube 560 combines the second polarizations, which change the direction at the second and fourth direction changing parts 552, 554, and provides the mixed second polarization to the second mixing tube 565. The third and fourth intermediate tubes 555, 560 are formed in substantially symmetry with reference to the second mixing tube 565.

[158] The parts of the third and fourth intermediate tubes 555, 560, which are connected with the first through fourth direction changing parts 551, 552, 553, 554, are narrower than that of the first through fourth direction changing parts 551, 552, 553, 554 in lateral width with reference to the propagation direction of the second polarization. Accordingly, an uneven surface 557 is formed on a connecting area between the third intermediate tube 555 and the first and third direction changing parts 551, 553, and another uneven surface 562 is formed on a connecting area between the fourth intermediate tube 560 and the second and fourth direction changing parts 552, 554. That is, the uneven surfaces 557, 562 are formed on opposite sides in the lateral width direction. Only one uneven surface 557, 562 may be formed on the length of the third intermediate tube 555 and the fourth intermediate tube 560. Alternatively, a plurality of uneven surfaces 557, 562 may be provided.

[159] A fourth and fifth extension parts 556, 561 are extended each to a substantially square pillar configuration, from the middle parts of the linear tubes of the third and fourth intermediate tubes 555, 560 towards the branch tubes. The fourth and fifth extension parts 556, 561 are also extended vertically, to connect the top and bottom sides of the third and fourth intermediate tubes 555, 560. The second polarizations from the first and third direction changing parts 551, 553 change electric field directivities by about 90 degrees by the fourth extension part 556, and the second polarizations with the changed directivities are mixed with each other and propagated toward the second mixing tube 565. Likewise, the second polarizations from the second and fourth direction changing parts 552, 554 change electric field directivities by about 90 degrees by the fifth extension part 561, and the second polarizations with the changed directivities are mixed with each other and propagated towards the second mixing tube 565.

[160] The second mixing tube 565 may be formed in a substantially 'T' configuration. The second mixing tube 565 combines the second polarizations provided from the third and fourth intermediate tubes 555, 560, and discharges the mixed second polarization so that the second polarizations are mixed with the second polarization from another antenna unit. The connecting areas of the second mixing tube 565 with the third and fourth intermediate tubes 555, 560 are narrower than the third and fourth intermediate tubes 555, 560 in lateral width with reference to the propagation direction of the second polarization, and accordingly, the connecting areas of the second mixing tube 565 with the third and fourth intermediate tubes 555, 560 have uneven surfaces 567 formed on opposite sides in the lateral width direction. A sixth extension part 566 is extended from a part of the second mixing tube 565, where the second polarization from the third intermediate tube 555 is mixed with the second polarization from the fourth intermediate tube 560, and the sixth extension part 566 is extended inwards the second mixing tube 565. The sixth extension part 566 is formed in a substantially square pillar configuration, and also extended vertically, to connect the top and bottom surfaces of the second mixing tube 565.

[161] The second polarizations from the third and fourth intermediate tubes 555, 560 change electric field directivities by about 90 degrees when the second polarization meets the sixth extension part 566, and the second polarizations with the changed directivities are mixed with each other and discharged. The frequency of the second polarization, entering into and exiting out of the second polarization guide 550, may be adjusted according to the thickness and length of the fourth through sixth extension parts 566, and the width and height of the reflective surfaces 569.

[162] Fig. 32 is a transparent perspective view of a T-type distribution tube according to another embodiment of the present invention.

[163] The first through fourth intermediate tubes 535, 540, 555, 560 and the first and second mixing tubes 545, 565 are formed in substantially the same configuration, with only one difference in width. Accordingly, the T-type distribution tube as illustrated in Fig. 32 may be used not only as the first through fourth intermediate tubes 535, 540, 555, 560, but also as the first and second mixing tubes 545, 565.

[164] The T-type distribution tube includes a linear tube, and a branch tube extended from the middle part of the linear tube. According to an exemplary embodiment of the present invention, the T-type distribution tube has a width gradually decreasing towards the middle part in the lengthwise direction, thereby forming an uneven surface. The uneven surface is formed on the only one side of the linear tube in the lengthwise direction, where there is no branch tube connected.

[165] Fig. 33 is a transparent perspective view of a T-type distribution tube according to yet another embodiment of the present invention.

[166] The T-type distribution tube illustrated in Fig. 33 has a plurality of uneven surfaces formed along the lengthwise direction of the linear tube. The uneven surfaces may be formed on only one side of the linear tube to which the branch tube is connected.

[167] Although Figs. 32 and 33 illustrate the T-type distribution tube having a plurality of uneven surfaces, in an alternative example, only one uneven surface may be formed. Also, although the T-type distribution does not have an uneven surface formed on the branch tube, as illustrated in Fig. 34, uneven surface may be formed along the lengthwise direction of the branch tube in a decreasing width towards the free end. By forming the uneven surfaces on the branch tube, the width of the branch tube, which is increased to be larger than the linear tube, can be reduced to original size, and the loss due to the width reduction of the tube can be minimized.

[168] The process in which the waves are divided into the first and second polarizations and received through the horn array antenna 1 for dual linear polarization constructed as explained above, will be explained below.

[169] As electric waves enter through the horns 10, the electric waves are guided along the gradients 15, passed the ledges 17, and provided to the polarization filtering unit 20. Because the polarization filtering unit 20 has a gradually decreasing width on its one side due to the presence of the uneven surface 25, the first polarization, which has electric field directivity identical to that of the longer width of the polarization filtering unit 20, does not pass the polarization filtering unit 20, but enters into the first polarization guide 530 through an aperture of the polarization filtering unit 20 which faces the first polarization guide 530. The second polarization, which has the same electric field directivity as that of the shorter width of the polarization filtering unit 20, propagates downward along the polarization filtering unit 20 and enters into the second polarization guide 550.

[170] Among the electric waves received through the four horns 10, the first polarization enters into the apertures of the first through fourth guide tubes 531, 532, 533, 534 of the first polarization guide 530. In the first intermediate tube 535, the first polarizations provided from the first and second guide tubes 531, 532 change the electric field directivities by about 90 degrees due to the first extension part 536, and mixed with each other. In the second intermediate tube 540, the first polarizations provided from the third and fourth guide tubes 533, 534 change the electric field directivities by about 90 degrees due to the second extension part 541, and mixed with each other. The first polarizations provided from the first and second intermediate tubes 535, 540 are guided to the first mixing tube 545. In the first mixing tube 545, the first polarizations provided from the first and second intermediate tubes 535, 540 change the electric field directivities due to the third extension part 546, are mixed with each other, and exit through the discharge tube 548.

[171] The second polarization, which is guided along the second polarization guide 550 through the polarization filtering unit 20, has substantially the same electric field directivity as the narrower width of the polarization filtering unit 20. The second polarization propagate through the first through fourth direction changing parts 551, 552, 553, 554, and change the direction at the projection parts 568 formed on the first through fourth direction changing parts 551, 552, 553, 554. The second polarizations are reflected against the reflective surfaces 569 of the first through fourth direction changing parts 551, 552, 553, 554, thus propagate through the third and fourth intermediate tubes 555, 560, are mixed at the fourth and fifth extension parts 556, 561, and propagate to the second mixing tube 565. The second polarizations provided from the third and fourth intermediate tubes 555, 560 are mixed with each other at the sixth extension part 566 of the second mixing tube 565, and the mixed second polarization propagate through the second mixing tube 565 and exit.

[172] The process in which the first and second polarization are transmitted from the horn array antenna 1 for dual linear polarization, will be explained below.

[173] The second polarization, being entered into the second mixing tube 565 of the second polarization guide 550, is divided through the sixth extension part 566, and guided through the third and fourth intermediate tubes 555, 560. The second polarization is once again divided due to the fourth and fifth extension parts 556, 561 in the third and fourth intermediate tubes 555, 560, and the divided polarizations are reflected against the reflective surfaces 569 of the direction changing parts 551, 552, 553, 554 and provided to the projection parts 568, respectively. The second polarizations each change the direction towards the polarization filtering unit 20 due to the respective projection parts 568, and rise through the polarization filtering unit 20.

[174] Meanwhile, the first polarization, being entered into the first mixing tube 545 through the discharge tube 548 of the first polarization guide 530, is divided in the third extension part 546, and transmitted to the first and second intermediate tubes 535, 540, respectively. In the first and second intermediate tubes 535, 540, the first polarization change the direction towards the respective guide tubes 531, 532, 533, 534 due to the first and second extension parts 536, 541, reflected against the first gradients 549a and propagate towards the respective apertures. The first polarizations, being entered to the polarization filtering units 20 through the apertures, are mixed with the second polarization provided from the second polarization guide 550, and radiated to the air through the gradients 15.

[175] The structure of the antenna unit to form the horn array antenna for dual linear polarization 1 as explained above, will be explained below.

[176] Fig. 35 is an exploded perspective view of respective layers of a horn array antenna for dual linear polarization according to the present invention, Fig. 36 is a upper view of the first layer shown in Fig. 35, and Fig. 37 is a perspective view of the first layer shown in Fig. 35. [177] The horn array antenna for dual linear polarization according to an exemplary embodiment of the present invention includes a first layer 600, a second layer 650, a third layer 700, a fourth layer 750, and a fifth layer 800. [178] The first layer 600 is formed as a divider 70. That is, the divider 70 having a plurality of ribs 75 in a column and row arrangement, is formed as the first layer 600.

The ribs 75 are arranged such that the divider 70 of the first layer 600 is divided into sixteen (16) divisions with respect to one antenna unit. [179] Fig. 38 is a perspective view of the second layer shown in Fig. 35, Fig. 39 is a upper view of the second layer shown in Fig. 35, and Fig. 40 is a bottom view of the second layer shown in Fig. 35. [180] The gradients 15 and the ledges 17 of the horns 10 are formed on the second layer

650, in which the gradients 15 are formed on the upper side of the first layer 600, and interior apertures are formed on the bottom side of the first layer 600. [181] Fig. 41 is a perspective view of the third layer shown in Fig. 35, Fig. 42 is a upper view of the third layer shown in Fig. 35, and Fig. 43 is a bottom view of the third layer shown in Fig. 35. [182] The polarization filtering units 20, connected with the interior apertures of the second layer 650, are formed on the third layer 700, in a manner such that the polarization filtering units 20 are passed through the areas adjacent to the edges of the second layer 650. Uneven surfaces 25 and ledges 19 are formed on the inside of the polarization filtering units 20. [183] The upper parts of the first through fourth guide tubes 531, 532, 533, 534, the first and second intermediate tubes 535, 540, the first mixing tube 545 and the discharge tube 548 of the first filtering guide 530, are formed on the rear side of the third layer

700. [184] Fig. 44 is a perspective view of the fourth layer shown in Fig. 35, Fig. 45 is a upper view of the fourth layer shown in Fig. 35, and Fig. 46 is a bottom view of the fourth layer shown in Fig. 35. [185] A lower part of the first polarization guide 530 is formed on the upper side of the fourth layer 750, the upper part of the second polarization guide 550 is formed on the lower side of the fourth layer 750, and the polarization filtering units 20 are passed through the fourth layer 750. [186] In other words, the lower parts of the first through fourth guide tubes 531, 532, 533,

534, the first and second intermediate tubes 535, 540, the first mixing tube 545, and the discharge tube 548 of the first polarization guide 530, are formed on the upper side of the fourth layer 750. The upper parts of the third and fourth intermediate tubes 555, 560 and the second mixing tube 565 of the second polarization guide 550, are formed on the lower side of the fourth layer 750.

[187] Fig. 47 is a perspective view of the fifth layer shown in Fig. 35, and Fig. 48 is a upper view of the fifth layer shown in Fig. 35.

[188] The lower part of the second polarization guide 550 is formed on the fifth layer 800.

The fifth layer 800 forms the second polarization guide 550 in association with the fourth layer 750, and the first through fourth direction changing parts 551, 552, 553, 554, the third and fourth intermediate tubes 555, 560, and the second mixing tube 565 are formed on the fifth layer 800. The projection parts 568 and the reflective surfaces 569 are formed within the first through fourth direction changing parts 551, 552, 553, 554 of the fifth layer 800.

[189] Fig. 49 is a perspective view illustrating a horn array antenna in use according to the present invention, Fig. 50 is a upper view of the horn array antenna shown in Fig. 49, Fig. 51 is a perspective view of the first layer of the horn array antenna shown in Fig. 49, and Fig. 52 is a perspective view of the second layer shown in Fig. 49.

[190] The horn array antenna according to an exemplary embodiment of the present invention includes 72 horns in 6 rows and 12 columns (6x12=72), which are divided into 18 antenna units (3x6=18). Accordingly, the splitter 70 shown in Fig. 51 includes 288 apertures (12x24=288) to divide the waves, and the second layer 650 as shown in Fig. 52 includes 72 horns 10.

[191] Fig. 53 is a upper perspective view of the third layer of the horn array antenna shown in Fig. 49, Fig. 54 is a bottom perspective view of the third layer shown in Fig. 49, and Fig. 55 is a upper perspective view of the fourth layer shown in Fig. 49.

[192] The horn array antenna according to an exemplary embodiment of the present invention includes 18 antenna units, and also includes 18 of the first polarization guides 530 formed on the lower side of the third layer 700 and on the upper side of the fourth layer 750. The first polarization guides 530 are arranged such that the number of the first polarization guides 530 is in the ratio of 1:2 or 2:1 in the row and column. The first polarization guides 530 may be provided by the multiples of number 3. That is, three of the first polarization guides 530, as the multiple of number 3, may be arranged in a row direction, and six of the first polarization guides 530, again as the multiple of number 3, may be arranged in a column direction. The first polarizations provided from the respective first polarization guides 530 are combined into a single first polarization, and emitted from the horn array antenna. To do this, the third layer 700 includes a gradient 230 formed on the lower side between the first polarization guide #7 530g and the first polarization guide #8 530h, and due to the presence of the gradient 230, the first polarization propagates through a first polarization main aperture 755 which is formed in the fourth layer 750.

[193] The first polarization guides #1 and #2 530a, 530b are in substantially symmetry with each other, and a first symmetric distribution tube #1 701, in substantially 'T' configuration, is formed on the ends of the discharge tubes 548 of the first polarization guides #1 and #2 530a, 530b. An end of the first symmetric distribution tube #1 701 extends to surround the first polarization guide #2 530b. Accordingly, the first polarizations provided from the first polarization guides #1 and #2 530a, 530b are mixed with each other, and the mixed first polarization propagates along the first symmetric distribution tube #1 701.

[194] Not only the first symmetric distribution tube #1 701 explained above, but also the second through fourteenth symmetric distribution tubes #1 702-704, which will be explained below, are in substantially 'T' configurations, in which opposite ends of linear tube of the 'T' configuration include ports 1 and 2, and an end of the branch tube of the 'T' configuration includes port 3. The symmetric distribution tubes #1 702-704 are formed such that the ports 1 and 2 have the widths narrower than the width of the discharge tube 548 connected to the ports 1 and 2, or narrower than the width of the branch tubes of the other symmetric distribution tubes #1 701-714. Accordingly, uneven surfaces are formed on the areas of the ports 1 and 2 of the symmetric distribution tubes #1 701-714.

[195] The first polarization guides #3 and #4 530c, 530d are formed in substantially symmetry with each other, and a second symmetric distribution tube #1 702, in substantially 'T' configuration, is formed on the ends of the discharge tubes 548 of the first polarization guides #3 and #4 530c, 530d. Accordingly, the first polarizations provided from the first polarization guides #3 and #4 530c, 530d are mixed with each other in the second symmetric distribution tube #1 702.

[196] The first polarization guides #5 and #6 530e, 530f are formed in substantially symmetry with each other, and in substantially parallel relation with the first polarization guides #3 and #4 530c, 530d. The ends of the discharge tubes 548 of the first polarization guides #5 and #6 530e, 530f are connected with the third symmetric distribution tube #1 703. Accordingly, the first polarizations provided from the first polarization guides #5 and #6 530e, 530f are mixed with each other in the third symmetric distribution tube #1 703.

[197] The ends of the second symmetric distribution tube #1 702 and the third symmetric distribution tube #1 703 are connected by the fourth symmetric distribution tube #1 704, and the branch tube of the fourth symmetric distribution tube #1 704 extends to surround the first polarization guide #4 530d and extends towards the first symmetric distribution tube #1 701.

[198] The first symmetric distribution tube #1 701 and the fourth symmetric distribution tube #1 704 are connected with each other at their ends, by a first asymmetric distribution tube 721. The first asymmetric distribution tube 721 is formed such that, as shown in Fig. 56, the port 1, connected with the first symmetric distribution tube #1 701, has a plurality of uneven surfaces and thus has a gradually decreasing width, and the port 2, connected with the fourth symmetric distribution tube #1 704, includes a guiding surface to reflect the first polarization. The first polarization provided from the first symmetric distribution tube #1 701 are the first polarizations propagating from the first polarization guides #1 and #2 530a, 530b, and the first polarization provided from the fourth symmetric distribution tube #1 704 is the first polarizations propagating from the first polarization guides #3~#6 530c~530f. In other words, as the first polarization, in 2 parts, is provided from the first symmetric distribution tube #1 701 and enters through the port 1, and the first polarization, in 4 parts, is provided from the fourth symmetric distribution tube #1 704 and enters through the port 2, the first polarization enters through ports 1 and 2 in the ratio of 1:2 and mixed with each other.

[199] The first polarization guides #7~#12 530g~5301, and the first polarization guides

#13~#18 530m~530r are in almost similar arrangement with that of the first polarization guides #1~#6 530a~530f, and are arranged on the lower side of the third layer 700 and on the upper side of the fourth layer 750 in substantially parallel relation with each other.

[200] The discharge tubes 548 of the first polarization guides #7 and #8 530g, 530h are connected with each other by the fifth symmetric distribution tube #1 705, and the fifth symmetric distribution tube #1 705 extends to surround the first polarization guide #8 530h. Accordingly, the first polarizations provided from the first polarization guides #7 and #8 530g, 530h are mixed with each other in the fifth symmetric distribution tube #1 705, and propagates along the fifth symmetric distribution tube #1 705.

[201] The discharge tubes 548 of the first polarization guides #9 and #10 530i, 530j are connected with each other by the sixth symmetric distribution tube #1 706, and the discharge tubes 548 of the first polarization guides #11 and #12 530k, 5301 are connected with each other by the seventh symmetric distribution tube #1 707. The sixth symmetric distribution tube #1 706 and the seventh symmetric distribution tube #1 707 are connected with each other by the eighty symmetric distribution tube #1 708 disposed between the first polarization guides #10 and #12 530j, 5301. Accordingly, the first polarizations provided from the first polarization guides #9 and #10 530i, 530j are mixed with each other in the sixth symmetric distribution tube #1 706, and the first polarizations provided from the first polarization guides #11 and #12 530k, 5301 are mixed with each other in the seventh symmetric distribution tube #1 707. The first polarizations provided from the sixth and seventh symmetric distribution tubes #1 706, 707 are then mixed with each other in the eighth symmetric distribution tube #1 708 and propagates.

[202] The discharge tubes 548 of the first polarization guides #13 and #14 530m, 530n are connected with each other by the ninth symmetric distribution tube #1 709, and the first polarizations provided from the first polarization guides #13 and #14 530m, 530n are mixed with each other in the ninth symmetric distribution tube #1 709. The ninth symmetric distribution tube #1 709 extends to surround the first polarization guide #13 530m. A third symmetric distribution tube #1 713 is formed between the first polarization guides #8 and #13 530h, 530m to connect the fifth and ninth symmetric distribution tubes #1 705, 709, and the first polarization provided from the first polarization guides #8 and #13 530h, 530m are mixed in the thirteenth symmetric distribution tube #1 713.

[203] The discharge tubes 548 of the first polarization guides #15 and #16 530o, 530p are connected with each other by the tenth symmetric distribution tube #1 710, and the first polarization provided from the first polarization guides #15 and #16 530o, 530p are mixed with each other in the tenth symmetric distribution tube #1 710. The discharge tubes 548 of the first polarization guides #17 and #18 530q, 530r are connected with each other by the eleventh symmetric distribution tube #1 711, and the first polarization provided from the first polarization guides #17 and #18 530q, 530r are mixed with each other by the eleventh symmetric distribution tube #1 711.

[204] The tenth and eleventh symmetric distribution tubes #1 710, 711 are connected with each other by the twelfth symmetric distribution tube #1 712 which is arranged in the middle of the first polarization guides #15~#18 530o~530r, and the first polarization provided from the tenth and eleventh symmetric distribution tubes #1 710, 711 are mixed in the twelfth symmetric distribution tube 712.

[205] The twelfth and eighth symmetric distribution tubes #1 712, 708 extend towards each other, and connected with each other by the fourteenth symmetric distribution tube #1 714, and the first polarization provided from the twelfth and eighth symmetric distribution tubes #1 712, 708 are mixed in the fourteenth symmetric distribution tube #1 714.

[206] The thirteenth and fourteenth symmetric distribution tubes #1 713, 714 extend towards each other, and connected with each other by the second asymmetric distribution tube 722. the second asymmetric distribution tube 722 is configured in a manner similar to the first asymmetric distribution tube 721, and accordingly, port 1 connected with the thirteenth symmetric distribution tube #1 713 has a plurality of uneven parts and thus has a decreasing width, and port 2 connected with the fourteenth symmetric distribution tube #1 714 has a gradient surface to reflect the first polarization. The first polarization provided from the thirteenth symmetric distribution tube #1 713 are the first polarization propagating from the first polarization guides #7 and #8 530g, 530h, and the first polarization guides #13 and #14 530m, 530n, and the first polarization provided from the fourteenth symmetric distribution tube #1 714 is the first polarization propagating from the first polarization guides #9~#12 530i~5301, and the first polarization guides #15~#18 530o~530r. In other words, as the first polarization, in 4 parts, enters into the second asymmetric distribution tube 722 from the thirteenth symmetric distribution tube #1 713, and the first polarization, in 8 parts, enters from the fourteenth symmetric distribution tube #1 714, the first polarization are mixed with entering through ports 1 and 2 in the ratio of 1:2, and discharged.

[207] The branch tubes of the first and second asymmetric distribution tubes 721, 722 extend toward each other, and ends of the branch tubes are connected with each other by a third asymmetric distribution tube 723. The third asymmetric distribution tube 723 includes port 1, which is connected with the first asymmetric distribution tube 721 and which has a plurality of uneven parts and thus has a gradually decreasing width, and port 2, which is connected with the second asymmetric distribution tube 722 and which has an inclined guiding surface to reflect the first polarization. The first polarization provided from the first asymmetric distribution tube 721 is the first polarization propagating from the first polarization guides #1~#6 530a~530f, and the first polarization provided from the second asymmetric distribution tube 722 is the first polarization propagating from the first polarization guides #7~#18 530g~530r. As the first polarization, in 6 parts, enters into the third asymmetric distribution tube 723 from the first asymmetric distribution tube 721, and the first polarization, in 12 parts, enters from the second asymmetric distribution tube 722, the first polarization enters into ports 1 and 2 in the ratio of 1:2 and mixed with each other. The mixed first polarization is reflected against the gradient 230 formed between the first polarization guides #7 and #8 530g, 530h, and guided toward the first polarization main aperture 755 formed in the fourth layer 750.

[208] Fig. 57 is a bottom perspective view of the fourth layer of the horn array antenna shown in Fig. 49, Fig. 58 is a upper perspective view of the fifth layer shown in Fig. 49, and Fig. 59 is a bottom perspective view of the fifth layer shown in Fig. 49.

[209] As the horn array antenna according to an exemplary embodiment of the present invention includes 18 antenna units, there are 18 of the second polarization guides 550 formed on the lower side of the fourth layer 750 and on the upper side of the fifth layer 800. The second polarization provided from the second polarization guides 550 are mixed into a single second polarization, and emitted from the horn array antenna. To do so, the fifth layer 800 includes a second polarization main aperture 855, which is pierced through the fifth layer 800, between the second polarization guides #8 and #10 550h, 550j.

[210] The second polarization guides #1 and #2 550a, 550b are in symmetry with each other, and the second mixing tubes 565 of the second polarization guides #1 and #2 550a, 550b are bent at one ends in substantially 'D' configuration and extended, and connected with a first symmetric distribution tube #2 801 in substantially 'T' configuration.

[211] The first symmetric distribution tube #2 801, and the other symmetric distribution tubes including second through fourteenth symmetric distribution tubes #2 802-814, are in substantially 'T' configuration, which includes ports 1 and 2 at opposite ends of the linear tube, and port 3 at an end of the branch tube. The ports 1 and 2 have width narrower than the second mixing tube 565 or the branch tubes of the other symmetric distribution tubes #2 801-814, such that the ports 1 and 2 of the respective symmetric distribution tubes #2 801-814 have uneven parts formed thereon.

[212] The second polarization guides #3 and #5 550c, 550e are in substantially symmetry with each other, and the second mixing tubes 565 of the second polarization guides #3 and #5 550c, 550e are connected with each other at one ends by the second symmetric distribution tube #2 802. Accordingly, the second polarization provided from the second polarization guides #3 and #5 550c, 550e are mixed in the second symmetric distribution tube #2 802.

[213] The second polarization guides #4 and #6 550d, 550f are in symmetry with each other, and the second mixing tubes 565 of the second polarization guides #4 and #6 550d, 550f are connected with each other by the third symmetric distribution tube #2 803. Accordingly, the second polarization provided from the second polarization guides #4 and #6 550d, 550f are mixed in the third symmetric distribution tube #2 803.

[214] The second and third symmetric distribution tubes #2 802, 803 are connected with each other at one ends by the fourth symmetric distribution tube #2 804, and accordingly, the second polarization from the second and third symmetric distribution tubes #2 802, 803 are mixed in the fourth symmetric distribution tube #2 804.

[215] The ends of the first and fourth symmetric distribution tubes #2 801, 804 extend toward each other, and are connected with each other by a fourth asymmetric distribution tube 824. The fourth asymmetric polarization guides 824 is configured such that the part connected with the first symmetric distribution tube #2 801 has a gradually decreasing width along the lengthwise direction, and an inclined guiding surface to reflect the second polarization is formed in a part connected to the fourth symmetric distribution tube #2 804. The second polarization provided from the first symmetric distribution tube #2 801 is the second polarization propagating from the second polarization guides #1 and #2 550a, 550b, and the second polarization provided from the fourth symmetric distribution #2 804 is the second polarization propagating from the second polarization guides #3~#6 550c~550f. As the second polarization, in 2 parts, enters into the fourth asymmetric distribution tube 824 from the first symmetric distribution tube #2 801, and the second polarization, in 4 parts, enters into the fourth symmetric distribution tube #2 804, the second polarization enters through the ports 1 and 2 in the ratio of 1 :2.

[216] The second polarization guides #7 and #8 550g, 550h are substantially parallel with the second polarization guides #1 and #2 550a, 550b, and the second mixing tubes 565 of the second polarization guides #7 and #8 550g, 550h are bent toward each other substantially in 'D' configuration and extended. The second mixing tubes 565 of the second polarization guides #7 and #8 550g, 550h are connected with each other at one ends by the fifth symmetric distribution tube #2 805, and the second polarization from the second polarization guides #7 and #8 550g, 550h are mixed with each other in the fifth symmetric distribution tube #2 805.

[217] The mixing tubes 565 of the second polarization guides #9 and #11 550i, 550k extend toward each other, and are connected with each other by the sixth symmetric distribution tube #2 806. The second mixing tubes 565 of the second polarization guides #10 and #12 550j, 5501 extend toward each other, and are connected with each other by the seventh symmetric distribution tube #2 807. Accordingly, the second polarization from the second polarization guides #9 and #11 550i, 550k are mixed in the sixth symmetric distribution tube #2, and the second polarization from the second polarization guides #10 and #12 550j, 5501 are mixed with each other in the seventh symmetric distribution tube #2 807.

[218] The sixth and seventh symmetric distribution tubes #2 806, 807 are connected with each other by the eighty symmetric distribution tube #2 808, and the second polarization from the sixth and seventh symmetric distribution tubes #2 806, 807 are mixed with each other by the eighty symmetric distribution tube #2 808.

[219] The eighth and fifth symmetric distribution tubes #2 808, 805 extend towards each other, and are connected with each other by a fifth asymmetric distribution tube 825. The fifth asymmetric distribution tube 825 is configured such that a part connected to the eighthy symmetric distribution tube #2 808 has a gradually decreasing width along the lengthwise direction, and an inclined guiding surface to reflect the second polarization is formed in a part connected to the eighth symmetric distribution tube #2 808. The second polarization provided from the fifth symmetric distribution tube #2 805 is the second polarization propagating from the second polarization guides #7 and #8 550g, 550h, and the second polarization provided from the eighth symmetric distribution tube #2 808 is the second polarization propagating from the second polarization guides #9~#12 550i -5501. As the second polarization, in 2 parts, enters into the fifth asymmetric distribution tube 825 from the fifth symmetric distribution tube #2 805, and the second polarization, in 4 parts, enters from the eighth symmetric distribution tube #2 808, the second polarizations enter through the ports 1 and 2 in the ratio of 1:2, and are mixed with each other.

[220] Ports 3 of the fourth and fifth asymmetric distribution tubes 824, 825 extend toward each other, and are connected with each other by the ninth symmetric distribution tube #2 809. The fourth and fifth asymmetric distribution tubes 824, 825 have a plurality of uneven parts and thus have a gradually decreasing width towards the ends thereof.

[221] Port 3 of the ninth symmetric distribution tube #2 809 extends to between the second polarization guides #6 and #11 550f, 550k, and is bent, and extended along the outer boundary of the second polarization guides #11 and #12 550k, 5501.

[222] The second mixing tubes 565 of the second polarization guides #13 and #14 550m,

550n are bent towards each other, and connected by the tenth symmetric distribution tube #2 810. Accordingly, the second polarizations from the second polarization guides #13 and #14 550m, 550n are mixed in the tenth symmetric distribution tube #2 810.

[223] The mixing tubes 565 of the second polarization guides #15 and #17 550o, 550q are connected with each other by the eleventh symmetric distribution tube #2 811, such that the second polarizations from the second polarization guides #15 and #17 550o, 550q are mixed in the eleventh symmetric distribution tube #2 811. The mixing tubes 565 of the second polarization guides #16 and #18 550p, 550r are connected with each other by the twelfth symmetric distribution tube #2 812, such that the second polarizations from the second polarization guides #16 and #18 550p, 550r are mixed in the twelfth symmetric distribution tube #2 812.

[224] The eleventh and twelfth symmetric distribution tubes #2 811, 812 are connected with each other by the thirteenth symmetric distribution tube #2 813, and the second polarizations from the second polarization guides #15~#18 550o~550r are mixed with each other in the thirteenth symmetric distribution tube #2 813. The thirteenth and tenth symmetric distribution tubes #2 813, 810 extend towards each other, and are connected with each other at one ends by a sixth asymmetric distribution tube 826.

[225] The sixth asymmetric distribution tube 826 is configured such that a part connected to the tenth symmetric distribution tube #2 810 has a gradually decreasing width along the lengthwise direction, and a part connected to the thirteenth symmetric distribution tube #2 813 includes an inclined guiding surface to reflect the second polarization. The second polarization provided from the tenth symmetric distribution tube #2 810 is the second polarizations propagating from the second polarization guides #13 and #14 550m, 550n, and the second polarization provided from the thirteenth symmetric distribution tube #2 813 is the second polarizations propagating from the second polarization guides #15~#18 550o~550r. Accordingly, as the second polarizations, in 2 parts, enters from the tenth symmetric distribution tube #2 810 into the sixth asymmetric distribution tube 826, and the second polarization, in 4 parts, enters from the thirteenth symmetric distribution tube #2 813, the second polarization enters through the ports 1 and 2 in the ratio of 1:2 and mixed with each other.

[226] The sixth asymmetric distribution tube 826 includes a plurality of uneven parts and thus has a gradually decreasing width towards the end thereof. The end of the sixth asymmetric distribution tube 826, which has the narrow width, is extended to between the second polarization guides #14 and #16 550n, 550p, bent to surround the second polarization guides #16 and #18 550p, 550r, bent again at the edge of the second polarization guide #18 550r, and extends to reach the boundary of the second polarization guide #17 550q.

[227] The sixth asymmetric distribution tube 826 and the ninth symmetric distribution tube #2 809 are connected with each other by a seventh asymmetric distribution tube 827, between the second polarization distribution tubes #12 and #17 5501, 550q. The seventh asymmetric distribution tube 827 is configured such that a part connected to the sixth asymmetric distribution tube 826 has a gradually decreasing width along the lengthwise direction, and an inclined guiding surface to reflect the second polarization is formed on a part connected to the ninth symmetric distribution tube #2 809. The second polarization provided from the sixth asymmetric distribution tube 826 is the second polarizations propagating from the second polarization guides #13~#18 550m~550r, and the second polarization provided from the ninth symmetric distribution tube #2 809 is the second polarizations propagating from the second polarization guides #1~#12 550a~5501. As the second polarization, in 6 parts, enters from the sixth asymmetric distribution tube 826 into the seventh asymmetric distribution tube 827, and the second polarization, in 12 parts, enters from the ninth symmetric distribution tube #2 809 into the seventh asymmetric distribution tube 827, the second polarizations enter through the ports 1 and 2 in the ratio of 1:2 and mixed with each other. The mixed second polarization propagates along the branch tube of the seventh asymmetric distribution tube 827. The branch tube of the seventh asymmetric distribution tube 827 is extended to between the second polarization guides #10 and #15 550j, 550o, and bent to between the second polarization guides #8 and #10 550h, 550j. a second polarization main aperture 855 is formed in an end of the branch tube of the seventh asymmetric distribution tube 827, in the proximity to the first polarization main aperture 755, and the second polarization is entered or exited through the second polarization main aperture 855. Accordingly, the second polarization, combined in the seventh asymmetric distribution tube 827, is emitted out through the second polarization main aperture 855.

[228] In the horn array antenna 1 for dual linear polarization according to the above exemplary embodiments of the present invention, by providing the ledges 17 in the horns 10, the height of the horns 10 can be reduced, without compromising the efficiency of the antenna 1. Because the first and second polarization guides 530, 550 have the horizontal widths greater than the heights, the size of the antenna 1 can be reduced vertically and horizontally. Also as illustrated in Table 1, the horn array antenna 1 having the reduced size provides unaffected performance.

[229] Because the first and second polarization guides 530, 550 have the uniform heights, the horn array antenna 1 for dual linear polarization according to the exemplary embodiments of the present invention can have simple structure and thus is easy to fabricate.

[230] The horn array antenna 1 for dual linear polarization according to the exemplary embodiments of the present invention can reduce the height of the horns 10, without compromising the efficiency, by providing the ledges 17 to the horns 10. Because the second polarization guides 550 have a horizontal width greater than the height, the height of the second polarization guides 550 can be reduced, and the overall size of the horn array antenna 1 can be reduced. Although the size is reduced, the horn array antenna 1 still provides unaffected performance, as illustrated in Table 3.

[231] Although the first and second polarizations refer to the electric field waves in the above exemplary embodiments, one will understand that the first and second polarization also apply to the magnetic field waves. Additionally, the structure of the horns 10, the first polarization guides 530, the second polarization guides 550 should be construed as an example of the prevent invention. As occasion demands, at least two of the horns 10, the first polarization guides 530, or the second polarization guides 550 may be fabricated at once by appropriate manner such as injection molding. In fabricating the horns 10, the first polarization guides 530 and the second polarization guides 550, the number of layers shown in Figs. 37 through 59 should not be construed as limiting.

Claims

[1] A horn array antenna for dual linear polarization, comprising: one or more horns tapered along a propagation direction of an electric wave, to guide the electric wave; a first polarization guide to guide a first polarization separated from the electric wave provided by the horns, the first polarization guide having a horizontal width in the direction of the first polarization narrower than a height; and a second polarization guide to guide a second polarization which is provided from the horns and is at a substantially perpendicular relation with the first polarization, the second polarization guide having a horizontal width in the direction of the second polarization narrower than a height.

[2] The horn array antenna of claim 1, wherein the horns each comprise: a gradient to guide the electric wave, and including a ledge extended from an interior aperture facing the first polarization guide towards the center; and a polarization filtering unit to connect the gradient with the first polarization guide.

[3] The horn array antenna of claim 2, wherein one side of the polarization filtering unit includes a plurality of uneven parts such that the polarization filtering unit has a gradually decreasing width towards the first polarization guide.

[4] The horn array antenna of claim 3, wherein the polarization filtering unit comprises a projection formed on a plane facing the uneven parts.

[5] The horn array antenna of claim 1, further comprising a splitter connected to an upper part of each of the horns, to divide openings of the horns into a plurality of apertures, the splitter comprising a plurality of ribs in lattice arrangement in which the ribs are spaced apart from each other by a predetermined distance in lateral and longitudinal directions.

[6] The horn array antenna of claim 1, wherein the first polarization guide comprises: a first through fourth guide tubes having openings in fluid connection with the polarization filtering unit; a first intermediate tube connecting the first and second guide tubes, and combining or separating the first polarization; a second intermediate tube connecting the third and fourth guide tubes, and combining or separating the first polarization; and a first mixing tube arranged between the first and second intermediate tubes, to connect the first and second intermediate tubes, and combine or separate the first polarization.

[7] The horn array antenna of claim 8, wherein the first through fourth guiding tubes each comprise a tube in substantially 'D' configuration, and a first inclined surface formed on a bent part of the tube to reflect the first polarization.

[8] The horn array antenna of claim 6, wherein a part of the first intermediate tube connected to the first and second guide tubes has a width narrower than that of the first and second guide tubes, thereby having an uneven surface thereon, and a part of the second intermediate tube connected to the third and fourth guide tubes has a width narrower than that of the third and fourth guide tubes, thereby having an uneven surface thereon.

[9] The horn array antenna of claim 6, comprising: a first extension part in substantially square-pillar configuration, extended from a center of the first intermediate tube connecting the first and second guide tubes, inwards across the lengthwise direction of the first intermediate tube; and a second extension part in substantially square-pillar configuration, extended from a center of the second intermediate tube connecting the third and fourth guide tubes, inwards across the lengthwise direction of the second intermediate tube.

[10] The horn array antenna of claim 6, wherein the first mixing tube comprises an uneven part formed on a part connected to the first and second intermediate tubes, the uneven part having a width narrower than that of the first and second intermediate tubes.

[11] The horn array antenna of claim 6, wherein the first mixing tube comprises a third extension part in substantially square-pillar configuration, extended from a center of the first mixing tube connecting the first and second intermediate tubes, inwards across the lengthwise direction of the first mixing tube.

[12] The horn array antenna of claim 6, wherein a discharge tube is extended from an end of the first mixing tube and is bent at least once.

[13] The horn array antenna of claim 1, wherein the second polarization guide comprises: first through fourth direction changing parts connected with the polarization filtering unit, to change the propagation direction of the second polarization; a third intermediate tube connecting the first and third direction changing parts; a fourth intermediate tube arranged in substantially symmetry with the third intermediate tube, and connecting the second and fourth direction changing parts; and a second mixing tube connecting the third and fourth intermediate tubes, and guiding the second polarization to enter or exit.

[14] The horn array antenna of claim 13, wherein the first through fourth direction changing parts are upwardly open and connected with the polarization filtering unit, and each comprises a projection formed on a bottom to change the propagation direction of the second polarization, and a reflective surface to reflect the second polarization towards the third and fourth intermediate tubes.

[15] The horn array antenna of claim 13, wherein the third intermediate tube comprises an uneven surface formed on a part connected to the first and third direction changing parts, which has a narrower width than that of the first and third direction changing parts, and the fourth intermediate tube comprises an uneven surface formed on a part connected to the second and fourth direction changing parts, which has a narrower width than that of the second and fourth direction changing parts.

[16] The horn array antenna of claim 13, wherein the third intermediate tube comprises a fourth extension part in substantially square-pillar configuration extended from a center connecting the first and third direction changing parts, inwards across the lengthwise direction of the third intermediate tube; and the fourth intermediate tube comprises a fifth extension part in substantially square-pillar configuration extended from a center connecting the second and fourth direction changing parts, inwards across the lengthwise direction of the third intermediate tube.

[17] The horn array antenna of claim 13, wherein the second mixing tube comprises an uneven surface formed on a part connected with the third and fourth intermediate tubes, as the width becomes narrower than that of the third and fourth intermediate tubes.

[18] The horn array antenna of claim 13, wherein the second mixing tube comprises a sixth extension part in substantially square-pillar configuration, extended from a center connected with the third and fourth intermediate tubes, inwards across the lengthwise direction of the second mixing tube.

[19] A horn array antenna for dual linear polarization, comprising: a first layer to form a splitter which comprises a plurality of ribs in lattice arrangement, in which the ribs are spaced apart from each other in lateral and longitudinal directions; a second layer on which a plurality of horns are formed to guide an electric wave to enter or exit; a third layer on which a first polarization guide is formed to guide the first polarization and is connected with the horns; a fifth layer on which a second polarization guide is formed in substantially parallel relation with the first polarization guide to guide a second polarization which has a propagation direction substantially perpendicular to that of the first polarization and is connected with the horns; and a fourth layer arranged between the third and fifth layers, to form a lower part of the first polarization guide and to form an upper part of the second polarization guide.

[20] The horn array antenna of claim 19, wherein the horns on the second layer each comprises a gradient tapered along the propagation direction of the electric wave, and a ledge projected from an interior aperture formed at an end of the gradient of a narrower width, towards a center.

[21] The horn array antenna of claim 19, wherein the first polarization guide formed by the third and fourth layers comprises: a first through fourth guide tubes each comprising an opening connected with the polarization filtering unit; a first intermediate tube connecting the first and second guide tubes, and combining or separating the first polarization; a second intermediate tube connecting the third and fourth guide tubes, and combining or separating the first polarization; and a first mixing tube arranged between the first and second intermediate tubes, to connect the first and second intermediate tubes, and combine or separate the first polarization.

[22] The horn array antenna of claim 20, wherein the third and fourth layers comprise: one or more symmetric distribution tubes each comprising a linear tube which is connected with the same number of the first polarization guides at opposite ends, and a branch tube extended from the middle part of the linear tube; and one or more asymmetric distribution tubes each comprising a linear tube connected with the first polarization guides in the ratio of l:n at opposite ends, and a branch tube extended from the middle part of the linear tube, wherein the symmetric distribution tubes are connected with the same number of the other symmetric distribution tubes at opposite ends, and the asymmetric distribution tubes are connected with the different number of the symmetric distribution tubes or of the other asymmetric distribution tubes.

[23] The horn array antenna of claim 22, wherein the opposite ends of the linear tube of each of the symmetric distribution tubes is formed narrower than the width of the connected tube.

[24] The horn array antenna of claim 22, wherein one end of the linear tube of each of the asymmetric distribution tubes comprises at least one uneven surface which has a width gradually decreasing towards the other end along the lengthwise direction.

[25] The horn array antenna of claim 22, wherein an end of the branch tube of each of the asymmetric distribution tubes comprises at least one uneven surface which has a width gradually decreasing towards the end.

[26] The horn array antenna of claim 22, wherein the fourth and fifth layers comprises a first polarization main aperture connected with an end of the branch tube of the asymmetric distribution tubes, through which the first polarization enters or exits.

[27] The horn array antenna of claim 19, wherein the second polarization guide formed on the lower side of the fourth layer and on the upper side of the fifth layer comprises: a first through fourth direction changing parts connected with the polarization filtering unit, to change the propagation direction of the second polarization; a third intermediate tube to connect the first and third direction changing parts; a fourth intermediate tube arranged in substantially symmetry with the third intermediate tube, to connect the second and fourth direction changing parts; and a second mixing tube to connect the third and fourth intermediate tubes, and guide the second polarization to enter or exit.

[28] The horn array antenna of claim 27, wherein the fourth and fifth layers comprise: one or more symmetric distribution tubes each comprising a linear tube which is connected with the same number of the second polarization guides at opposite ends, and a branch tube extended from the middle part of the linear tube; and one or more asymmetric distribution tubes each comprising a linear tube connected with the second polarization guides in the ratio of l:n at opposite ends, and a branch tube extended from the middle part of the linear tube, wherein the symmetric distribution tubes are connected with the same number of the other symmetric distribution tubes at opposite ends, and the asymmetric distribution tubes are connected with the different number of the symmetric distribution tubes or of the other asymmetric distribution tubes.

[29] The horn array antenna of claim 28, wherein the opposite ends of the linear tube of each of the symmetric distribution tubes is formed narrower than the width of the connected tube.

[30] The horn array antenna of claim 28, wherein one end of the linear tube of each of the asymmetric distribution tubes comprises at least one uneven surface which has a width gradually decreasing towards the other end along the lengthwise direction.

[31] The horn array antenna of claim 28, wherein an end of the branch tube of each of the asymmetric distribution tubes comprises at least one uneven surface which has a width gradually decreasing towards the end.

[32] The horn array antenna of claim 28, wherein the fifth layer comprises a second polarization main aperture connected with an end of the branch tube of the asymmetric distribution tubes, through which the second polarization enters or exits.

[33] The horn array antenna of claim 27, wherein the fifth layer comprises a projection formed on a bottom of each of the first through fourth direction changing parts to change the propagation direction of the second polarization, and a reflective surface to reflect the second polarization towards the third and fourth intermediate tubes.