JP2008148149A - Antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attenuate a high-order mode capable of propagating in a rectangular waveguide capable of propagating a high-order mode.
A radiation waveguide 10 and a feeding waveguide 17 made of a rectangular waveguide are arranged in two layers with their tube axes orthogonal to each other, and perpendicular to the tube axis on a first wide side surface 11A. A first radiation slot 16 is formed so as to form a second radiation slot 13 parallel to the first radiation slot 12 and the tube axis, and to excite the second radiation slot 13 at a position facing the second radiation slot 13. , And a step structure 14 is provided on the inner surface of the radiation waveguide 10 to narrow the distance between the first wide side surface 11A and the second wide side surface 11B to an interval that reduces the propagation of higher-order modes. The antenna device is characterized in that the second radiation slot 13 is excited through the first feeding slot 16.
[Selection] Figure 1

Description

  The present invention relates to an antenna device, and more particularly to an antenna device that transmits and receives radio waves using a slot provided in a rectangular waveguide.

  As this type of conventional antenna device, for example, there is one disclosed in Japanese Patent Laid-Open No. 2003-133850. FIG. 6 is a perspective view of this conventional waveguide slot antenna device. FIG. 7 shows a radio wave having a plane of polarization parallel to the tube axis 7 of the radiation waveguide 3 formed of a rectangular waveguide radiated from the first radiation slot 1 in the waveguide slot antenna apparatus of FIG. It is explanatory drawing explaining radiation. FIG. 8 is an explanatory view for explaining a case where a radio wave having a polarization plane orthogonal to the tube axis 7 is radiated from the second radiation slot 2. Here, 4A is an upper surface which is one wide side surface of the radiation waveguide 3, 4B is a lower surface which is the other wide side surface of the radiation waveguide 3, and 5 is a power feeding composed of the radiation waveguide 3 and a rectangular waveguide. Feed slots formed at the same position on the surface facing the waveguide 6 for use, 8 is a path of radio waves when exciting the first radiation slot 1, and 9 is when exciting the second radiation slot 2. It is an arrow indicating the path of radio waves. In this example, a case is shown in which an array antenna device is formed by arranging a plurality of radiation waveguides 3 in a direction perpendicular to the tube axis 7.

  As shown in the radio wave path 8, the radio wave propagated through the radiation waveguide 3 is radiated from the first radiation slot 1. Since the first radiation slot 1 is arranged in such a direction as to cut the current parallel to the tube axis 7, it emits radio waves having a plane of polarization parallel to the tube axis 7 in the air. On the other hand, the radio wave propagated through the power supply waveguide 6 as indicated by the radio wave path 9 is radiated from the second radiation slot 2 into the air via the power supply slot 5. Here, in order to excite the second radiation slot 2, the distance between the second radiation slot 2 and the power supply slot 5 is set to a half length of the free space wavelength. Thus, by radiating polarized waves orthogonal to each other from the same aperture from one radiation waveguide, there is an advantage that the number of radiation waveguides is reduced and the manufacturing cost of the waveguide slot antenna device is reduced.

JP 2003-133850 A (FIGS. 1 to 3)

  However, in the conventional waveguide slot antenna apparatus, in order to excite the second radiation slot 2, it is necessary to set the distance between the second radiation slot 2 and the feed slot 5 to a length half of the free space wavelength. Therefore, the radiation waveguide 3 has a problem that a higher-order mode can propagate and phase distortion occurs due to interference between modes, and transmission loss increases.

  An object of the present invention is to solve the above-mentioned problems of the prior art, and to obtain a waveguide slot antenna device in which a high-order mode capable of propagation is attenuated. It is another object of the present invention to obtain a waveguide slot antenna device that attenuates higher-order modes that can be propagated and is impedance-matched to the fundamental mode.

  An antenna apparatus according to the present invention includes a radiation waveguide and a feed waveguide formed of a rectangular waveguide having a rectangular cross section having first and second wide side surfaces facing each other, and a second wide waveguide of the radiation waveguide. The side surface and the first wide side surface of the feeding waveguide are aligned, the tube axes are orthogonal to each other, and the two layers are arranged to overlap each other, and the radiation waveguide tube is disposed on the first wide side surface of the radiation waveguide. Forming a first radiation slot perpendicular to the axis and a second radiation slot provided on the tube axis and parallel to the tube axis, the first on the tube axis of the second wide side surface of the radiation waveguide; Forming a first feeding slot parallel to the tube axis so as to excite the second radiating slot at a position facing the two radiating slots, and forming the first feeding side surface of the feeding waveguide on the first wide side surface. Forming a second feeding slot that feeds the radiation waveguide through the first feeding slot; The inner surface and is characterized in that a convex portion to narrow the interval between the first wide side surface and a second broad side surface of said radiating waveguides interval to reduce the propagation of higher order modes.

  According to the present invention, the inner surface of the radiation waveguide is provided with a convex portion that narrows the distance between the first wide side surface and the second wide side surface of the radiation waveguide to an interval that reduces the propagation of higher-order modes. Therefore, higher order modes that can propagate through the radiating waveguide can be attenuated, phase distortion due to interference between modes can be reduced, and an antenna device with a small transmission loss can be obtained.

Embodiment 1 FIG.
FIG. 1 is a configuration explanatory view showing an antenna apparatus according to Embodiment 1 of the present invention. FIG. 2 is a top view of the antenna device of FIG. In the figure, reference numeral 10 denotes a radiation waveguide composed of a rectangular waveguide having a rectangular cross section having first and second wide side surfaces facing each other, 11A denotes a first wide side surface of the radiation waveguide 10, and 11B denotes a radiation waveguide. A second wide side surface 12 of the tube 10 is formed on the first wide side surface 11A of the radiating waveguide 10 and radiates a radio wave having a polarization plane parallel to the tube axis of the radiating waveguide 10. A slot 13 is formed on the first wide side surface 11A of the radiation waveguide 10 and a second radiation slot 14 radiates a radio wave having a plane of polarization perpendicular to the tube axis of the radiation waveguide 10. It is a convex portion formed on the inner surface of the second wide side surface 11B of the tube 10, and here is a step structure 14 having a step-like protrusion extending in a direction perpendicular to the tube axis of the radiation waveguide 10. Also, parallel to the tube axis so as to excite the second radiation slot 13 at a position facing the second radiation slot 13 on the tube axis 15 on the second wide side surface of the radiation waveguide 10. A first power supply slot 16 is formed. Reference numeral 17 denotes a feeding waveguide formed by a rectangular waveguide having a rectangular cross section having first and second wide side surfaces facing each other. The feeding waveguide 17 is orthogonal to the radiating waveguide 10 in two layers. A second feed slot is formed on the first wide side surface of the feed waveguide 17 facing the first feed slot 16 so as to overlap with the radiation waveguide 10 via the first feed slot 16. Excited by electromagnetic coupling. In the antenna device according to the first embodiment of the present invention, the case where the first radiating slot 12 and the second radiating slot 13 are formed at the same position on the first wide side surface 11A to form a cross slot will be described as an example. To do. The step structure 14 is opposed to a portion between the adjacent second radiation slots 13 of the first wide side surface 11A of the radiation waveguide 10 in a direction orthogonal to the tube axis 15 of the radiation waveguide 10. Provided on the second wide side surface 11B. The step structure 14 is provided at a position between the adjacent second radiation slots 13 of the first wide side surface 11A of the radiation waveguide 10 in a direction orthogonal to the tube axis 15 of the radiation waveguide 10. Also good. Here, A is the width of the radiation waveguide 10, and B is the height of the radiation waveguide 10. H is the height of the step-like protrusions inside the radiation waveguide 10 of the step structure 14, L is the length of the step structure 14 in the direction of the tube axis 15, and D is the first radiation slot 12 and the step structure 14. And the distance.

  FIG. 3 is an explanatory diagram for explaining the radiation of a radio wave having a plane of polarization parallel to the tube axis 15 of the radiation waveguide 10 radiated from the first radiation slot 12 in the antenna device of FIG. Reference numeral 18 denotes an arrow indicating a path of a radio wave when the first radiation slot 12 is excited. FIG. 4 is an explanatory view for explaining a case where a polarized wave having a polarization plane orthogonal to the tube axis 15 of the radiating waveguide 10 is radiated from the second radiating slot 13, and 19 denotes the second radiating slot 13. It is an arrow showing the path | route of the electromagnetic wave to excite.

Next, the operation will be described.
As shown in FIG. 3, the radio wave traveling through the radiation waveguide 10 excites the first radiation slot 12. The radio wave traveling to the radiation waveguide 10 may be supplied from the end of the radiation waveguide 10 by a power feeding means (not shown) such as another waveguide. At this time, when a fundamental mode that is a component perpendicular to the first wide side surface 11A of the radiation waveguide 10 is excited, the characteristic impedance changes in the step structure 14.
On the other hand, as shown in FIG. 4, in order to couple the radio wave propagating through the feed waveguide 17 to the second radiation slot 13 via the first feed slot 16, the free space wavelength is λ. The height of the radiation waveguide 10 needs to be λ / 2. In such a setting, a higher-order mode is generated in the radiation waveguide 10.

  In the antenna device illustrated in the first embodiment, the excitation of the first radiation slot 12 and the second radiation slot 13 is electrically switched by feeding power to the radiation waveguide 10 or the feed waveguide 17. Can change the plane of polarization.

Since the antenna device according to the present invention has the step structure 14, it is possible to attenuate a higher-order mode that can be propagated by adjusting the height H of the step structure 14 or the like. Furthermore, impedance matching can be achieved by adjusting the height H and length L of the step structure 14 and the distance D between the step structure 14 and the first radiation slot 12.
The fact that such an effect can be obtained by the step structure 14 will be described below.

The attenuation amount P _A (> 0) is expressed using the attenuation constant α and the length L of the step structure 14.

  Here, the attenuation constant α is given by the following equation using B and H, where λ is a free space wavelength.

  From equations (1) and (2), it can be seen that when (B−H) <λ / 2, α is a real number and the higher-order mode is suppressed.

In a rectangular waveguide capable of propagating higher-order modes, there are problems such as phase distortion due to interference between modes and an increase in transmission loss. However, this problem can be avoided by providing the step structure 14 as described above.
Furthermore, the impedance matching of the radiation waveguide 10 can be performed by adjusting the dimensions of the step structure 14.

  Therefore, the antenna device according to the first embodiment of the present invention is provided on the same radiation waveguide 10 capable of high-order mode propagation in the first radiation slot 12 and the second radiation slot 13 whose polarization planes are orthogonal to each other. In this structure, impedance matching can be achieved and higher-order modes can be attenuated by the step structure 14 of the first wide side surface 11A or the second wide side surface 11B of the radiation waveguide 10.

  In addition, although the case where a plurality of first radiation slots 12 and second radiation slots 13 are formed at the same position to form a cross slot has been described as an example, the present invention is not limited to this, and is a diagram described as a prior art As in the case of the waveguide slot antenna device 6, even if the first radiation slot 12 and the second radiation slot 13 are separately disposed on the first wide side surface 11 </ b> A of the radiation waveguide 10, the same effect as described above. Can be obtained.

  In addition, from the above, in the waveguide slot antenna apparatus that radiates orthogonally polarized waves at the same aperture from one radiating waveguide capable of propagating higher order modes, the step structure 14 only reduces the higher order modes. In addition, there is an effect of impedance matching. Therefore, in addition to the case where a plurality of radiating waveguides 10 capable of high-order mode propagation as illustrated in FIG. 1 are arranged in a direction perpendicular to the tube axis 15 to form an array antenna, high-order mode propagation is also possible. This is also effective in the case where the antenna is formed by one possible radiating waveguide 10.

In the above description, as illustrated in FIG. 1, the case where the radiating waveguide 10 and the feeding waveguide 17 are configured by stacking two layers with their tube axes orthogonal to each other has been described. The present invention is not limited to such a configuration. Depending on the application of the antenna device, a configuration using one radiation waveguide capable of propagating higher-order modes may be used. In this case as well, effects of lowering higher-order modes and impedance matching are obtained.
The configuration of the radiation waveguide is such that the first wide side surface of the radiation waveguide is a rectangular waveguide having a rectangular cross section having first and second wide side surfaces facing each other, and is perpendicular to the tube axis of the radiation waveguide. 1 or a plurality of first radiation slots (corresponding to the first radiation slots) for radiating radio waves having a plane of polarization parallel to the tube axis are formed, and the first or second wide side surface of the radiation waveguide is formed. Convex portions are formed on the inner surface of. Here, if the convex portion has a step structure of stepped protrusions extending in a direction perpendicular to the tube axis of the radiation waveguide, the same as described above.

  Moreover, even when each part of the radiation waveguide 10 has a curvature, the same effect is produced.

  In the above description, it is needless to say that the same effect can be obtained as a reception antenna from the transmission / reception reversibility of the antenna described as the transmission antenna.

  Further, in the above description, it is also possible to use one polarized wave exclusively for transmission and the other polarized wave exclusively for reception with respect to what has been described as transmitting and receiving two orthogonal polarized waves.

Embodiment 2. FIG.
An antenna device according to Embodiment 2 of the present invention is the antenna device according to Embodiment 1 described above, in which the whole or a part of the radiation waveguide is filled with a dielectric.

  In the antenna device according to the present invention, the arrangement interval of the respective radiation slots of the first radiation slot 12 or the second radiation slot 13 may be larger than the free space wavelength. At this time, an unnecessary grating lobe is generated in a direction different from that of the main lobe, which causes a decrease in gain and an ambiguity of the radiation pattern. Therefore, the wavelength can be shortened by filling the whole or a part of the air layer of the radiating waveguide with an appropriate dielectric, and the conditions for generating grating lobes can be avoided.

  As described above, according to the antenna device of the second embodiment, in addition to the effects of the first embodiment, the generation of grating lobes can be suppressed by filling the dielectric.

Embodiment 3 FIG.
FIG. 5 is a configuration explanatory diagram showing a partial cross section for explaining the configuration of the antenna device according to the third embodiment of the present invention. In the figure, reference numeral 20 denotes a linearly polarized wave / circularly polarized wave provided at a predetermined distance from the first wide side surface 11A, which is the radiation surface of the radiation waveguide 10, with respect to the antenna device of the first embodiment. It is a meander line polarizer as a conversion plate.

  Next, the operation will be described. When the linearly polarized wave radiated from the first radiation slot 12 or the second radiation slot 13 is incident on the meander line polarizer 20, the meander line polarizer 20 generates a circularly polarized wave according to the incident polarization plane. The meander line polarizer 20 generates two orthogonal circularly polarized waves (a right-handed circularly polarized wave and a left-handed circularly polarized wave) corresponding to each when the incident linearly polarized waves are orthogonal. Here, since linearly polarized waves orthogonal to each other are radiated from the first radiating slot 12 and the second radiating slot 13, right-handed circularly polarized light and left-handed circularly polarized wave corresponding to each are generated.

  Therefore, the antenna device according to Embodiment 3 of the present invention has an effect that two circularly polarized waves can be transmitted and received.

  In the above description, two orthogonal polarized waves are transmitted and received as an example. However, an amplitude difference or a phase difference is given to the polarized waves radiated from the first radiation slot 12 and the second radiation slot 13. Therefore, it is possible to synthesize a circularly polarized wave, an elliptically polarized wave, or a linearly polarized wave having an arbitrary polarization plane.

Embodiment 4 FIG.
In the first to third embodiments, for example, as shown in FIG. 1, the radiation waveguide 10 is provided with the first radiation slot 12 and the second radiation slot 13, as shown in FIGS. 3 and 4. The plane of polarization is changed by electrically switching the excitation of the first radiation slot 12 and the second radiation slot 13 by supplying power to the radiation waveguide 10 or the feeding waveguide 17, respectively.
On the other hand, in the antenna device according to the fourth embodiment of the present invention, the radiating waveguide 10 provided with the step structure 14 shown in FIG. The first radiation slot 12 is excited by supplying power to the waveguide 10, and the polarization plane is switched by changing the direction of the radiation waveguide 10 by mechanical drive.

  Therefore, in the antenna device according to the fourth embodiment of the present invention, the number of radiation slots provided in the radiation waveguide 10 can be reduced, the feeding waveguide 17 can be eliminated, and the number of waveguides can be reduced.

  Further, the tube axis of the radiation waveguide is formed on the first wide side surface of the radiation waveguide composed of the rectangular waveguide having the rectangular cross section having the first and second wide side surfaces opposed to each other as described in the first embodiment. One or more first radiation slots (corresponding to the first radiation slots) that radiate radio waves having a plane of polarization parallel to the tube axis are formed perpendicular to the first and second of the radiation waveguide. The present invention can also be applied to the case where one radiation waveguide having a convex portion formed on the inner surface of the wide side surface is used, and the polarization plane can be switched by changing the direction of the radiation waveguide by mechanical drive.

BRIEF DESCRIPTION OF THE DRAWINGS It is structure explanatory drawing which shows the antenna apparatus concerning Embodiment 1 of this invention. It is a top view of the antenna apparatus concerning Embodiment 1 of this invention. FIG. 6 is an explanatory diagram for explaining the radiation of a radio wave having a plane of polarization parallel to the tube axis 15 of the radiation waveguide 10 radiated from the first radiation slot 12. FIG. 6 is an explanatory diagram for explaining a case where a polarized wave having a polarization plane orthogonal to the tube axis 15 of the radiation waveguide 10 is radiated from the second radiation slot 13. It is the structure explanatory drawing shown in the partial cross section for demonstrating the structure of the antenna apparatus concerning Embodiment 3 of this invention. It is a perspective view of the conventional waveguide slot antenna apparatus. In the waveguide slot antenna apparatus of FIG. 6, an explanation will be given for radiation of a radio wave having a plane of polarization parallel to the tube axis 7 of the radiation waveguide 3 composed of a rectangular waveguide radiated from the first radiation slot 1. FIG. FIG. 7 is an explanatory diagram for explaining a case where a polarized wave having a polarization plane orthogonal to the tube axis 7 is radiated from the second radiation slot 2 in the waveguide slot antenna apparatus of FIG. 6.

Explanation of symbols

  1, 12 1st radiation slot, 2, 13 2nd radiation slot, 3, 10 radiation waveguide, 4A upper surface, 4B lower surface, 5 feeding slot, 6 feeding waveguide, 7, 15 tube axis, 8 Radio wave path for exciting the first radiation slot, 9 Radio wave path for exciting the second radiation slot, 11A First wide side surface, 11B Second wide side surface, 14 step structure, 16 1st , 17 feed waveguide, 18 radio wave path for exciting the first radiation slot, 19 radio wave path for exciting the second radiation slot, 20 meander line polarizer.

Claims (9)

A radiation waveguide and a feed waveguide, each of which is a rectangular waveguide having a rectangular cross section having first and second wide side surfaces facing each other, are connected to the second wide side surface of the radiation waveguide and the feed waveguide. The first wide side faces are aligned, the tube axes are orthogonal to each other and arranged in two layers, and a first radiation perpendicular to the tube axis of the radiation waveguide is disposed on the first wide side surface of the radiation waveguide. A slot and a second radiation slot which is provided on the tube axis and is parallel to the tube axis, and is opposed to the second radiation slot on the tube axis of the second wide side surface of the radiation waveguide; Forming a first feed slot parallel to the tube axis so as to excite the second radiation slot, and passing through the first feed slot on the first wide side surface of the feed waveguide. Forming a second feeding slot for feeding the radiation waveguide, and the inner surface of the radiation waveguide includes the radiation waveguide; Antenna apparatus characterized in that a convex portion to narrow a wide side and a distance between the second broad side to the interval to reduce the propagation of higher order modes. The antenna device according to claim 1, wherein a pair or a plurality of pairs of the first radiation slot and the second radiation slot are formed on the first wide side surface of the radiation waveguide. The antenna device according to claim 1 or 2, wherein the first radiation slot and the second radiation slot are formed at the same position to form a cross slot. The first wide side surface of the radiating waveguide, which is a rectangular waveguide having a rectangular cross section having first and second wide side surfaces facing each other, is provided with one or more first perpendicular to the tube axis of the radiating waveguide. And a projection that narrows the interval between the first wide side surface and the second wide side surface of the radiation waveguide to an interval that reduces the propagation of higher-order modes on the inner surface of the radiation waveguide. An antenna device comprising: The protrusion is a step-like protrusion extending in a direction perpendicular to the tube axis of the radiation waveguide, and the height and width of the protrusion and the distance from the first radiation slot position are determined by the radiation waveguide. The antenna device according to any one of claims 1 to 4, wherein the antenna device is set to a size that reduces propagation of higher-order modes and impedance matching. 6. The antenna device according to claim 1, wherein an array antenna is formed by arranging a plurality of the radiation waveguides in a direction perpendicular to a tube axis of the radiation waveguide. The antenna device according to claim 1, wherein at least a part of the radiation waveguide is filled with a dielectric. 8. The linearly polarized wave-circularly polarized wave conversion plate is provided at a position separated from the first wide side surface of the radiation waveguide by a predetermined distance, according to claim 1. The antenna device described. The antenna apparatus according to claim 1, further comprising a driving unit that mechanically drives the radiation waveguide, wherein the plane of polarization is changed by the driving by the driving unit.

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