CA2217730A1 - Planar array antenna - Google Patents
Planar array antenna Download PDFInfo
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- CA2217730A1 CA2217730A1 CA002217730A CA2217730A CA2217730A1 CA 2217730 A1 CA2217730 A1 CA 2217730A1 CA 002217730 A CA002217730 A CA 002217730A CA 2217730 A CA2217730 A CA 2217730A CA 2217730 A1 CA2217730 A1 CA 2217730A1
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- circularly polarized
- waveguides
- polarized wave
- antenna
- waveguide
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q21/00—Antenna arrays or systems
- H01Q21/0006—Particular feeding systems
- H01Q21/0037—Particular feeding systems linear waveguide fed arrays
- H01Q21/0043—Slotted waveguides
- H01Q21/005—Slotted waveguides arrays
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
- H01Q3/02—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical movement of antenna or antenna system as a whole
- H01Q3/04—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical movement of antenna or antenna system as a whole for varying one co-ordinate of the orientation
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- Variable-Direction Aerials And Aerial Arrays (AREA)
Abstract
A plurality of slots for transmitting or receiving circularly polarized electromagnetic waves are provided at prescribed places in a plurality of waveguides so arranged that their axes are parallel with each other or in a planar line. Two waveguides for feeding or two distribution circuits are connected to both ends of the waveguides. Electromagnetic waves are fed to the two waveguides or two distribution circuits, and counterclockwise- and clockwise-rotating polarized electromagnetic waves are transmitted from each slot. A device using such an antenna is also disclosed.
Description
CA 022l7730 l997-l0-08 E2465 ,.
DESCRIPTION
PLANAR ARRAY ANTENNA
TECHNICAL FIELD
The present invention relates to a planar array antenna and an apparatus including the same, and in particular, to a planar array antenna and an apparatus including the s~ame suitable for receiving waves of satellite broadcasting, the waves including a counterclockwise circularly polarized wave and a clockwise circularly polarized wave.
BACKGROUND ART
The conventional planar array antennas include, for example, a waveguide planar array antenna including a plurality of linear waveguides each having a plurality of slots arranged in parallel to an axial direction thereof, the slots radiating circularly polarized waves in the axial direction. Supplied to these waveguides are transmission waves via a power supplying or feeding circuit. This operation will be referred to as "power feeding" herebelow. According to an article "Design of a Crossed Slot Array Antenna on a Leaky Waveguide", Transactions of the Institute of Electronics, Information and Communication Engineers (IEICE) of Japan, AP92-37 (to be referred to as Article 1 herebelow), there has been disclosed an array antenna ' CA 02217730 1997-10-08 -including cross-slots to radiate circularly polarized waves therefrom and a feeding waveguide as a power distributing circuit. Fig. 14 shows a top view of the array antenna. In this diagram, the feeding waveguide 1 S includes a feed opening 2 and branch openings 3. A
plurality of radiating waveguides 11 are arranged in parallel to each other in a direction vertical to the feeding waveguide 1 to be connected via the branch openings 3 to the feeding waveguide 1. In each of the radiating waveguide 11, there are disposed a plurality of cross-slots 12 for radiating circularly polarized waves. The wave or power supplied from the feed opening 2 is delivered via the feeding waveguide 1 to be distri-buted in an in-phase state through the branch openings 3 to the radiating waveguides 11 so as to be radiated as circularly polarized waves via the cross-slots 12. The rotary direction of circularly polarized waves is decided as follows. When the slots 12 are on the right-hand side with respect to the direction in which the waves are transmitted from the radiating waveguide 11, the waves are counterclockwise circularly polarized.
When the slots are on the left-hand side, clockwise circularly polarized waves are radiated. Namely, in the example, of Fig. 14, the radiated waves are counter-clockwise circularly polarized. Description has beengiven of the transmission of waves from the antenna above. It is apparent according to the reciprocity theorem that the antenna can be used also to receive ' CA 02217730 1997-10-08 -waves.
The antenna shown in Fig. 14 can receive only either one of the counterclockwise and clockwise circu-larly polarized waves. However, both of the counter-clockwise and clockwise circularly polarized waves areutilized in the satellite broadcasting service in the U.S.A. and so on. That is, the antenna receiving only the counterclockwise or clockwise circularly polarized wave cannot cope with this situation.
To meet such a requirement, an antenna capable of radiating or receiving both of the counterclockwise and clockwise circularly polarized waves has been disclosed in an article "A Slot Design of Dual Circular Polarized Radial Line Slot Antennas", 1993 Spring Conference of IEICE of ~apan, B-49 (to be referred to as Article 2 herebelow). According to the antenna, through a radial waveguide as a radiating waveguide, there are transmitted inward and outward oriented cylindrical waves to thereby radiate the counterclockwise and clockwise circularly polarized waves. However, the antenna efficiency descr~ed in Article 2 is at most about 70% even when the sIots are optimally designed.
Namely, the antenna efficiency is insufficient for practices.
DISCLOSURE OF THE INVENTION
It is therefore an object of the present invention to provide an antenna and an apparatus ' CA 02217730 1997-10-08 including the same in which both of the counterclockwise and clockwise circularly polarized waves can be radiated or received with a high efficiency.
To achieve the object above, a planar array antenna according to a first aspect of the present invention includes a plurality of first waveguides arranged with axes thereof mutually in parallel to each other, each of the first waveguides having a plurality of slots at predetermined positions to radiate or to receive circularly polarized waves. The antenna further includes two second waveguides having axes of waveguide vertical to a direction of axes of the first waveguides, and respectively connected via junction openings to both ends of the first waveguides, the second waveguides having feed openings respectively. Counterclockwise and clockwise circularly polarized waves are radiated or received through each of the slots of the first wave-guides via the feed openings respectively of the second waveguides.
In the planar array antenna according to the first aspect of the present invention described above, when the slots to radiate or to receive circularly polarized waves are arranged with a predetermined offset respectively relative to the axes of the first wave-guides, both of the counterclockwise and clockwise circularly polarized waves can be radiated through each slot by feeding waves via the second waveguides respectively to both ends of the first waveguides.
- ' CA 02217730 1997-10-08 Conversely, it is possible to receive via each slot both of the counterclockwise and clockwise circularly polarized waves.
Furthermore, a planar array antenna according to a second aspect of the present invention includes a plurality of planar lines arranged mutually in parallel to each other, a conductive plate disposed with a predetermined interval wi-th respect to the plural planar lines, the plate having a plurality of slots for the plural planar lines to radiate or receive therethrough circularly polarized waves~ and two power distributing circuits respectively connected to both ends of the planar lines. CountercloCkwise and clockwise circularly polarized waves are radiated from or received through each of the slots of the first waveguides via the power distributing circuits.
In the planar array antenna according to the second aspect of the present invention described above, the similar operation can ~e achieved without using the waveguides. Namely, there are employed planar lines such as strip lines and micro-strip lines and slots disposed in a conductive case which covers the planar lines.
Unlike the antenna disclosed in Article 2, the planar array antenna acCording to the present invention has a high efficiency of 80% or more by optimizing the electric coupling between the waveguides or planar lines and the slots.
' CA 02217730 1997-10-08 In addition, there is provided according to the present invention an antenna apparatus including a planar array antenna for receiving waves of satellite broadcasting. The apparatus includes a plurality of first waveguides arranged with axes thereof mutually in parallel to each other, each of the first waveguides having a plurality of slots at predetermined positions to receive a first circularly polarized wave and a second circularly polarized wave; a second waveguide, including a plurality of guide sections for combining the first circularly polarized waves received by the first waveguides with each other, for transmitting the first circularly polarized wave thus combined; a third waveguide, including a plurality of guide sections for combining the second circularly polarized waves received by the first waveguides with each other, for trans-mitting the second circularly polarized wave thus combined; and converter means for converting into an intermediate fre~uency (IF) signal at least one of the first and second circularly polarized waves thus combined and transmitted through the second and third waveguides.
In the antenna apparatus according to the present invention described above, either one of the counterclockwise and clockwise circularly polarized waves received by the planar array antenna can be selected to be supplied to a tuner.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective view of a planar array antenna in a first embodiment according to the present invention;
Fig. 2 is a plan view of the planar array antenna in the first embodiment according to the present invention;
Fig. 3 is a plan view of a planar array antenna in a second embodiment according to the present invention;
Fig. 4 is a graph showing a relationship between the penetrating energy and antenna efficiency of the planar array antenna~ according to the present invention;
Fig. 5A is a plan view of a planar array antenna in a third embodiment according to the present invention;
Fig. 5B is a cross-sectional view of the planar array antenna in the third embodiment according to the present invention;
Fig. 6 is a schematic diagram of an antenna apparatus in a fourth embodiment according to the present invention;
Fig. 7 is a schematic diagram of an antenna apparatus in a fifth embodiment according to the present invention;
Fig. 8 is a schematic diagram of an antenna apparatus in a sixth embodiment according to the present ' ~ CA 02217730 1997-10-08 -invention;
Fig. 9 is a schematic diagram of an antenna apparatus in a seventh embodiment according to the present invention;
Fig. 10 is a schematic diagram of an antenna apparatus in an eighth embodiment according to the present invention;
Fig. llA is a plan view showing the overall configuration of the antenna apparatus according to the present invention;
Fig. llB is a side view showing the overall structure of the antenna apparatus according to the present invention;
Fig. 12A is a plan view of an antenna apparatus in a ninth embodiment according to the present invention;
Fig. 12B is a cross-sectional view of the antenna apparatus in the ninth embodiment according to the present invention;
Figs. 13A and 13B are plan views of an antenna apparatus in a tenth embodiment according to the present invention; and Fig. 14 is a plan view of a conventional planar array antenna for clockwise or counterclockwise circularly polarized waves.
BEST MODES OF CARRYING OUT THE INVENTION
Next, description will be given of an ~ CA 02217730 1997-10-08 >
embodiment of the present invention by referring to the drawings. Incidentally,~for convenience of explanation, description will be given of the wave radiating opera-tion of the antenna. However, according to the recipro-city theorem, it is to be understood that the antenna isalso applicable to the wave receiving operation.
Fig. 1 is a perspective view showing a first embodiment of a planar array antenna according to the present invention and Fig. 2 is a plan view of the antenna of Fig. 1. A feeding waveguide lA includes a feed opening 2A and branch openings 3A as guide means, whereas a feeding waveguide lB includes a feed opening 2B and branch openings 3B as guide means.
Respectively disposed in the neighborhood of the feed openings 2A and 2B are connecting or connector terminals 4A and 4B to establish connections via cables to external circuits. Each of the terminals 4A and 4B
includes a connector portion for the connection of the cable and a feed pin portion for the feeding of power to the antenna. In the connector portion, a cold side thereof is linked with a housing of the planar array antenna and a hot side thereof is coupled with the feed pin portion. Therefore, in a state in which the cable is connected to the connector, a cold side of the cable is liked with the housing of the antenna and a hot side thereof is coupled with the feed pin portion.
A plurality of radiating waveguides 11 arranged in parallel with each other are connected - ~ CA 02217730 1997-10-08 vertically to the feeding waveguides lA and lB via the branch openings 3A and 3B, respectively. In each of the radiating waveguides 11, there are disposed a plurality of cross-slots 12 to radiate circularly polarized waves.
Waves fed from the feed opening 2A are propagated through the feeding waveguide lA and are distributed in an equi-phase state via the branch openings 3A to the plural radiating waveguides 11 to be radiated as clock-wise circularly polarized waves from the cross-slots 12.
On the other hand, waves supplied from the feed opening 2B are passed through the feeding waveguide lB to be distributed in an in-phase state via the branch openings 3B to the plural radiating waveguides 11 so as to be radiated as counterclockwise circularly polarized waves from the cross-slots 12.
When the wave feeding operation is conducted respectively at both ends of the radiating waveguides 11 as described in relation to this embodiment, if there is employed a broad side array antenna in which the slots are disposed with an interval of guide wavelength ~g of the waveguide to radiate waves in front of the antenna, the antenna efficiency is remarkably lowered. This is because the guide wavelength ~g is larger than the free space wavelength ~0. That is, when the slot interval is greater than the free space wavelength ~0, there occurs a phenomenon called "grating robe" in which a side robe equal in the level to the main beam in the front direc-tion appears according to a fixed pattern in a wide - ~ CA 02217730 1997-10-08 angle.
To acquire a practical efficiency, it is necessary to configure a leaky wave array antenna in which the slots are tightly arranged with a small interval therebetween. In the antenna, the waves are radiated in a direction other than the front direction thereof. Namely, the radiating direction is tilted considerably toward the direction of axis of the feed waveguide. In consequence, the beam directions respec-tively of the counterclockwise and clockwise circularlypolarized waves are tilted in the mutually opposing directions and hence it is impossible, when the antenna is fixed, to receive both of the counterclockwise and clockwise circularly polarized waves. However, as described in Article 1, in a case in which the antenna attached, for example, on the roof of a car is rotated in a particular plane to follow a broadcasting satel-lite, the antenna is practical for the following reasons. Namely, since the elevation angles of these beams are the same to each other, when a change-over is required between the counterclockwise and clockwise circularly polarized waves, it is only necessary to rotate the antenna 180~ in the particular plane.
Fig. 3 is a plan view showing a second embodi-ment of the planar array antenna according to thepresent invention. This embodiment differs from the first embodiment in that the positions of slots are shifted between the adjacent waveguides 11 such that the - ' CA 02217730 1997-10-08 -phases respectively of the waves supplied thereto are opposite to each other. As described in an article "A
Waveguide Fed Printed Antenna", Transactions of IEICE of Japan, AP89-3, an advantage derived from the case in which the waves fed to the adjacent radiating waveguides are opposing in phase to each other resides in that the radiating waveguides can be constructed by attaching a groove-shaped structure onto a flat plate having slots therein and it is not necessarily required that the structure and the plate are completely tightly fixed to each other.
In a case in which the phases of the waves fed to the adjacent waveguides 11 are opposite to each other as shown in Fig. 3, when the leaky wave array antenna is employed, which leads to a reverse effect when compared with the case of Fig. 2, the waves emitted from the adjacent radiating waveguides have the mutually opposing phases and hence weaken each other. Namely, the radiation beams are not formed and the operation fails.
To overcome this difficulty, there will be considered the configuration of a broad side array antenna. For this purpose, radiating cross-slots 12 are arranged along the direction of axis of waveguides 11 with an interval of guide wavelength ~g such that between the adjacent waveguides 11, the position of each slot 12 is shifted ~g/2 in the direction of axis. Under this condition, when the waveguides 11 are filled with a dielectric substance the relative dielectric constant ~r of which is more than one, there is attained an advan-tage that the grating robe does not occur even if the broad side array antenna is employed, which differs from the case of Fig. 2. The reason therefor will be described. The grating robe occurs when the m~X; mum interval between the adjacent slot strings is greater than the free space wavelength ~0. In the antenna of Fig. 3, distance "h" indicates the m~Ximum interval.
Ignore the thickness of the wall of waveguide 11 and assume the width to be expressed as "a". Then, distance "h" is represented by the following expression:
~g : h = ( ) : a ............................ (1) On the other hand, it is well known that guide wavelength ~g of waveguide 11 is denoted as follows when waves are transmitted in a basic mode, TE10 mode.
= ... (2) / ( ~ )2 where, ~ is a wavelength in the dielectric and is represented as follows-Ao ;~ r ~ . ( 3 ) Simplifying expressions (1) and (2), distance"h" is finally equal to ~. Therefore, when relative inductivity ~r is slightly larger than one, h < ~0 holds and hence the grating robe does not take place. Addi-tionally, when the change in relative inductivity with respective to temperature and the like are taken into consideration, the value of relative inductivity is desirably at least about 1.1.
Since the planar array antenna of the embodi-ment is a broad side array antenna, the same radiating direction can be set for the counterclockwise and clockwise circularly polarized waves. In consequence, when the reception signal is desired to be switched between the counterclockwise and clockwise circularly polarized waves, it is unnecessary to turn the antenna.
Subsequently, description will be given of a high efficiency in practices of the planar array antenna according to the first or second embodiment.
In general, the efficiency of the planar array antenna takes the m~imum value when the radio wave , radiated from each radiation slot has the same ampli-tude. This condition is satisfied in the array antenna for the counterclockwise or clockwise circularly polarized waves by adjusting the length and positions of the slots along the axis of waveguides. Theoretically, the efficiency therefore becomes 100%.
In contrast therewith, according to the planar array antenna of the present invention, waves are fed from both sides of the radiating waveguides 11. When the antenna is designed such that the slot radiation becomes uniform for the waves fed from a first side of the waveguides 11, the slot radiation for the waves supplied from a second side opposing to the first side develops a distribution with a large gradient and hence the efficiency is remarkably lowered. In a simplest model in which there are arranged slots each having the same contour, waves are radiated from each slot with a fixed ratio and the remained energy penetrates through the waveguides 11 to be absorbed by the feeding wave-guide on the opposite side which is not in the feedingoperation.
Fig. 4 is a graph showing the calculated results of antenna efficiency obtained by changing the ratio of the penetrating energy. When the penetrating energy, i.e., the loss is about 8%, the antenna effici-ency takes the m~;mum value of about 81%. The effici-ency is higher than that of the radial line slot antenna described in Article 2 or the parabola antenna used in ' . CA 02217730 1997-10-08 >
practices today and hence this value is fully satis-factory for practical uses. The reason why the planar array antenna of the present invention has a higher efficiency when compared with the antenna described in Article 2 is as follows.
In the radial line slot antenna, the behavior of waves including an inward oriented cylindrical wave and an outward oriented cylindrical wave transmitted through the radiating radial waveguides is utilized to achieve the radiation of the counterclockwise and clockwise circularly polarized waves. In consequence, there is missing a condition under which the efficiency is increased for both of the counterclockwise and clockwise circularly polarized waves. In comparison therewith, the antenna according to the present inven-tion includes radiating waveguides having a uniform cross section like square waveguides. Consequently, the waves propagated through the waveguide in either direc-tions conduct substantially the same behavior. Accord-ingly, when the slots are symmetrically arranged withrespect to an intermediate point of the radiating waveguide, the condition of m~x;mllm efficiency for the counterclockwise circularly polarized waves becomes almost equal to that of ~ximum efficiency for the clockwise circularly polarized waves, which results in a high efficiency.
Next, description will be given of a third embodiment of the planar array antenna according to the present invention. Although the array antenna includes waveguides in the embodiments described above, the present invention is not restricted by the embodiments.
Namely, in place of the waveguides, there may be adopted micro-strip lines, strip lines, co-planar lines, slot lines, parallel flat plate lines, flat plane lines such as dielectric surface wave lines. Figs. 5A and 5B show the third embodiment of the planar array antenna employ-ing strip lines. Fig. 5A shows a plan view of the antenna and Fig. 5B is a cross-sectional view thereof taken along a line A-A of Fig. 5A. In a space enclosed with a conductive plate 33 and a conductive case 34, there are arranged two dielectric substrates 35 and 36 between which strip lines are configured. This configu-ration includes three conductors with two dielectricbodies therebetween and hence is called "tri-plate structure". The strip lines include a plurality of radiating lines 31 formed parallel to each other and distributing circuits 21A and 21B to supply signals to these lines 31 from both sides thereof. In addition, there are provided connector terminals 24A and 24B to respectively connect the circuits 21A and 21B to external circuits. In the conductor plate 33 opposing the radiating lines 31, there are disposed a plurality of circularly polarized wave radiating slots 32, each slot 32 including a pair of linear slots which are not parallel to each other.
The signal applied to the terminal 24A is ~ CA 02217730 1997-10-08 >
passed through the distributing circuit 21A to be fed in an in-phase state to the plural radiating lines 31 so as to be radiated as counterclockwise circularly polarized waves from the slots 32. On the other hand, the signal fed to the terminal 24B is emitted as clockwise circu-larly polarized waves from the pertinent slots 32.
In the first to third embodiments above, cross-slots and non-parallel slots are described as examples of the circularly polarized wave radiating slots. However, it is to be appreciated that the present invention is applicable to slots having other contours. Additionally, the shapes of the feeding wave-guide and the distributing circuit are not restricted by the embodiments. Namely, it is only necessary for the feeding waveguide and the distributing circuit to supply signals to the radiating waveguides or lines in a parallel fashion. Moreover, when planar lines are employed, a planar array antenna capable of radiating the counterclockwise and clockwise circularly polarized waves can be implemented using strip dipoles which electromagnetically has a complementary relationship with respect to the slots.
Next, description will be given of an antenna apparatus using such a planar array antenna as those described in the embodiments above. Figs. llA and llB
respectively are a plan view and a side view showing the overall configuration of the apparatus. However, for easy understanding of the inner configuration, a radome . CA 02217730 1997-10-08 as the cover is missing in Fig. llA and the radome is cut at the central portion thereof in Fig. llB. As means for rotating the antenna, there are provided a rotating unit 71 in a lower portion of the planar array antenna 41, a belt 72, a decelerator 73, a motor 74 and a motor drive circuit in a fixed-side circuit unit 75.
Furthermore, reference numeral 76 denotes a rotary-side circuit unit. The elevation angle of the antenna 41 is adjusted by an EL driver unit 77 and an EL motor 78.
Additionally, the rotating unit 71 includes slip rings arranged to transmit power and control signals to a rotary-side circuit unit 76, the EL motor 78, and con-verters 42A and 42B. These components are mounted on the base plate 79 and are covered with a radome 80.
Fig. 6 is a schematic diagram showing a fourth embodiment of the antenna apparatus according to the present invention. This apparatus includes a planar array antenna 41 which is similar to the antenna shown in the first embodiment and which is ratably attached, for example, on a roof of an automobile; converters 42A
and 42B connected respectively via connector terminals 4A and 4B to the antenna 41, capacitors 43A and 43B
respectively connected to the converters 42A and 42B to suppress direct-current (DC) components, a rotary coupler 44 electrically equivalent to a capacitor, and a tuner 45. In addition, a DC power source 49 is con-nected to the converterS 42A and 42B via switch circuits 48A and 48B either one of which is turned on by the ~ ~ CA 02217730 1997-10-08 control circuit 46, interference preventing resistors 47A and 47B, and/or slip rings arranged in the rotary unit 71 as shown in Fig. llB. When the DC voltage is applied to the signal output line, the converters 42A
and 42B down convert an RF (radio frequency) signal of satellite broadcasting from the antenna 41 into an IF
(intermediate frequency) signal. According to supplied information representing desired one of polarized waves, the control circuit 46 turns either one of the switch circuits 48A and 48B on, the switch circuit being on the side of the desired one of the circularly polarized waves. In consequence, according to the present embodi-ment, since only the intermediate frequency signal output from either one of the converters 42A and 42B to which the DC voltage is=applied is input to the tuner 45, it is possible to select the desired one of the polarized waves. In this connection, the number of capacitors may be reduced ~y configuring the capacitors 43A and 43B with rotary couplers in place of the rotary coupler 44.
Furthermore, when the switch circuits are disposed in the signal lines, not in the power source lines, as shown in the flfth embodiment as shown in Fig.
7, the desired one of the polarized waves can be selected. In Fig- 7, two intermediate frequency signals output from the converters 42A and 42B are respectively fed via the DC suppressing capacitors 51A and 51B such that either one thereo~is selected by the switch 52 to ~ ~ CA 02217730 1997-10-08 be input to the tuner 45- On the other hand, the DC
voltage is supplied to the converters 42A and 42B.
Incidentally, rotary couplers are not shown in this embodiment because rotary couplers may be used as the DC
suppressing capacitors 51A and 51B. Alternatively, a rotary coupler may be arranged between the switch 52 and the tuner 45.
In the antenna apparatus as shown in Figs. 6 and 7, although the signal line of the converters 42A or 42B also serves as the power line, there may also be utilized converters of which these lines are separately provided.
In the sixth embodiment as shown in Fig. 8, intermediate frequency signals output from two converters 42A and 42B are linked with a rotary coupler 53 to be supplied therethrough to a tuner 45. Only the intermediate frequency signal output from either one of the converters 42A and 42B to which the DC voltage is applied is actually input to the tuner. Resultantly, there can be selected the desired one of the circularly polarized waves.
In addition, according to the seventh embodi-ment as shown in Fig- 9 L intermediate frequency signals sent from two converters 42A and 42B are acquired respectively via DC suppressing capacitors 51A and 51B
such that either one thereof is selected by a switch circuit 52 to be delivered to a tuner 45. On the other hand, the DC voltage is applied to the converters 42A
- ' CA 02217730 1997-10-08 and 42B. In this regard, rotary couplers are not shown in this embodiment, because rotary couplers may be used as the DC suppressing capacitors 51A and 51B. Or, rotary couplers may be provided between the switch 52 and the tuner 45. With this provision, it is possible to desirably select either one of the circularly polarized wave.
In the antenna facilities as shown in Figs. 6 to 9, although the counterclockwise or clockwise circu-larly polarized wave is selected through an electricswitching operation, the wave selection may also be conducted by altering the antenna direction.
The eighth embodiment of the present invention as shown in Fig. 10 includes antenna rotating means 63 to turn the planar array antenna 41 attached onto a roof of a car or the like. The means 63 includes a rotary unit 71, a belt 72, a decelerator 73, a motor 74, and a motor drive circuit in a fixed-side circuit unit 75 as shown in Fig. llB.
Referring to Fig. 10, two intermediate frequency signals produced from converters 42A and 42B
applied with the DC voltage are added to each other by adder means 61 to be fed via a rotating coupler 53 to a tuner 45. In this connection, the adder means 61 may be implemented, if the circuit configuration thereof is acceptable, by simply linking the outputs from the converters 42A and 42B with each other. On receiving polarized wave information denoting desired one of the circularly polarized waves and polarized wave informa-tion indicating a reception channel from the tuner 45, a control circuit 62 in the fixed-side circuit unit 75 decides whether or not these information items match with each other. If mismatching results, the controller 62 outputs a control signal to the antenna rotating means 63. In response to the signal, the means 63 turns the antenna 41 about 180 to thereby select the desired one of the polarized waves.
Referring now to Figs. 12A and 12B, descrip-tion will be given of the antenna apparatus in the ninth embodiment according to the present invention. Fig. 12A
is a plan view of the apparatus in which an upper sur-face unit (81 in Fig. 12B) having a plurality of slots is missing. Fig. 12B is a cross-sectional view of the antenna facility taken along line B-B of Fig. 12A. In this embodiment, a transmission unit 83 is arranged in a lower portion of an antenna body 82 so that the antenna can be operated only with one converter 85. In other words, the feed opening of the feeding waveguide as shown in the first embodiment is provided on the lower side, and the transmission unit 83 serving as a wave-guide is integrally fabricated therewith or is connected thereto. As a result, the feed openings on both sides of the antenna are linked with each other. Consequ-ently, for the counterclockwise and clockwise circularly polarized waves, the energy thereof can be radiated or received via a connector t~rm;n~l 84 with the single converter 85.
Subsequently, description will be given of the planar array antenna in the tenth embodiment according to the present invention by referring to Figs. 13A and 13B. In these diagrams, i.e., plan views of the antenna, an upper portion having a plurality of slots is missing for easy understanding of the structure. In this embodiment, inductive posts 93A and 93B of Fig. 13A
or inductive walls 94A and 94B of Fig. 13B are fabri-cated in the vicinity of branch openings 3A and 3B of afeeding waveguide to thereby m;nimi ze reflection of waves. The reflection minimi zing effect of inductive posts or walls has been described in detail in article "An Analysis of a Waveguide ~ Junction with an Inductive Wall", 1994 Spring Conference of IEICE of Japan, B-54 and in article "Characteristics of Single-Layer ~- and T-Junction with Inductive Wall", 1995 General Conference of IEICE of Japan, B-83. The inductive posts 93A and 93B can be attached after the antenna body 92 is comp-letely fabricated. Additionally, when the inductive walls 94A and 94B as well as the antenna body 92 are manufactured at the same time, the post-process will be unnecessary.
In the embodiments above, the connector terminals 4A and 4B are disposed in the proximity respectively of the feed openings 2A and 2B such that waves are communicated via a cable between the antenna body and the converter.- However, the present invention is not restricted by the embodiments, namely, the wave communication may be carried out in the following configurations.
First, the feed openings are each constructed in the form of a standard opening of waveguide, e.g., in conformity with the standard WR-75. In this structure, the input side of the converter is required to conform to the standard opening of waveguide. In short, the feed openings are used to pass waves therethrough.
Furthermore, only the feed pin sections of connector terminals 4A and 4B may be arranged in the feeding section of the converter in some cases. In this configuration, the cable is unnecessary. The feed openings function in the same way as for the construc-tion including the connector terminals 4A and 4B of the embodiments, namely, the opening is used to pass there-through the connector portions of the connector terminals.
In addition, although the connector terminals 4A and 4B or the connector terminal 84 are or is employed to couple the planar array antenna with the converter, the connection therebetween may be established without using the connector terminal(s) as described above.
INDUSTRIAL APPLICABILITY
As above, the planar array antenna according to the present invention is useful to transmit or to ' CA 02217730 1997-10-08 receive both of the counterclockwise and clockwise circularly polarized waves with a high efficiency.
DESCRIPTION
PLANAR ARRAY ANTENNA
TECHNICAL FIELD
The present invention relates to a planar array antenna and an apparatus including the same, and in particular, to a planar array antenna and an apparatus including the s~ame suitable for receiving waves of satellite broadcasting, the waves including a counterclockwise circularly polarized wave and a clockwise circularly polarized wave.
BACKGROUND ART
The conventional planar array antennas include, for example, a waveguide planar array antenna including a plurality of linear waveguides each having a plurality of slots arranged in parallel to an axial direction thereof, the slots radiating circularly polarized waves in the axial direction. Supplied to these waveguides are transmission waves via a power supplying or feeding circuit. This operation will be referred to as "power feeding" herebelow. According to an article "Design of a Crossed Slot Array Antenna on a Leaky Waveguide", Transactions of the Institute of Electronics, Information and Communication Engineers (IEICE) of Japan, AP92-37 (to be referred to as Article 1 herebelow), there has been disclosed an array antenna ' CA 02217730 1997-10-08 -including cross-slots to radiate circularly polarized waves therefrom and a feeding waveguide as a power distributing circuit. Fig. 14 shows a top view of the array antenna. In this diagram, the feeding waveguide 1 S includes a feed opening 2 and branch openings 3. A
plurality of radiating waveguides 11 are arranged in parallel to each other in a direction vertical to the feeding waveguide 1 to be connected via the branch openings 3 to the feeding waveguide 1. In each of the radiating waveguide 11, there are disposed a plurality of cross-slots 12 for radiating circularly polarized waves. The wave or power supplied from the feed opening 2 is delivered via the feeding waveguide 1 to be distri-buted in an in-phase state through the branch openings 3 to the radiating waveguides 11 so as to be radiated as circularly polarized waves via the cross-slots 12. The rotary direction of circularly polarized waves is decided as follows. When the slots 12 are on the right-hand side with respect to the direction in which the waves are transmitted from the radiating waveguide 11, the waves are counterclockwise circularly polarized.
When the slots are on the left-hand side, clockwise circularly polarized waves are radiated. Namely, in the example, of Fig. 14, the radiated waves are counter-clockwise circularly polarized. Description has beengiven of the transmission of waves from the antenna above. It is apparent according to the reciprocity theorem that the antenna can be used also to receive ' CA 02217730 1997-10-08 -waves.
The antenna shown in Fig. 14 can receive only either one of the counterclockwise and clockwise circu-larly polarized waves. However, both of the counter-clockwise and clockwise circularly polarized waves areutilized in the satellite broadcasting service in the U.S.A. and so on. That is, the antenna receiving only the counterclockwise or clockwise circularly polarized wave cannot cope with this situation.
To meet such a requirement, an antenna capable of radiating or receiving both of the counterclockwise and clockwise circularly polarized waves has been disclosed in an article "A Slot Design of Dual Circular Polarized Radial Line Slot Antennas", 1993 Spring Conference of IEICE of ~apan, B-49 (to be referred to as Article 2 herebelow). According to the antenna, through a radial waveguide as a radiating waveguide, there are transmitted inward and outward oriented cylindrical waves to thereby radiate the counterclockwise and clockwise circularly polarized waves. However, the antenna efficiency descr~ed in Article 2 is at most about 70% even when the sIots are optimally designed.
Namely, the antenna efficiency is insufficient for practices.
DISCLOSURE OF THE INVENTION
It is therefore an object of the present invention to provide an antenna and an apparatus ' CA 02217730 1997-10-08 including the same in which both of the counterclockwise and clockwise circularly polarized waves can be radiated or received with a high efficiency.
To achieve the object above, a planar array antenna according to a first aspect of the present invention includes a plurality of first waveguides arranged with axes thereof mutually in parallel to each other, each of the first waveguides having a plurality of slots at predetermined positions to radiate or to receive circularly polarized waves. The antenna further includes two second waveguides having axes of waveguide vertical to a direction of axes of the first waveguides, and respectively connected via junction openings to both ends of the first waveguides, the second waveguides having feed openings respectively. Counterclockwise and clockwise circularly polarized waves are radiated or received through each of the slots of the first wave-guides via the feed openings respectively of the second waveguides.
In the planar array antenna according to the first aspect of the present invention described above, when the slots to radiate or to receive circularly polarized waves are arranged with a predetermined offset respectively relative to the axes of the first wave-guides, both of the counterclockwise and clockwise circularly polarized waves can be radiated through each slot by feeding waves via the second waveguides respectively to both ends of the first waveguides.
- ' CA 02217730 1997-10-08 Conversely, it is possible to receive via each slot both of the counterclockwise and clockwise circularly polarized waves.
Furthermore, a planar array antenna according to a second aspect of the present invention includes a plurality of planar lines arranged mutually in parallel to each other, a conductive plate disposed with a predetermined interval wi-th respect to the plural planar lines, the plate having a plurality of slots for the plural planar lines to radiate or receive therethrough circularly polarized waves~ and two power distributing circuits respectively connected to both ends of the planar lines. CountercloCkwise and clockwise circularly polarized waves are radiated from or received through each of the slots of the first waveguides via the power distributing circuits.
In the planar array antenna according to the second aspect of the present invention described above, the similar operation can ~e achieved without using the waveguides. Namely, there are employed planar lines such as strip lines and micro-strip lines and slots disposed in a conductive case which covers the planar lines.
Unlike the antenna disclosed in Article 2, the planar array antenna acCording to the present invention has a high efficiency of 80% or more by optimizing the electric coupling between the waveguides or planar lines and the slots.
' CA 02217730 1997-10-08 In addition, there is provided according to the present invention an antenna apparatus including a planar array antenna for receiving waves of satellite broadcasting. The apparatus includes a plurality of first waveguides arranged with axes thereof mutually in parallel to each other, each of the first waveguides having a plurality of slots at predetermined positions to receive a first circularly polarized wave and a second circularly polarized wave; a second waveguide, including a plurality of guide sections for combining the first circularly polarized waves received by the first waveguides with each other, for transmitting the first circularly polarized wave thus combined; a third waveguide, including a plurality of guide sections for combining the second circularly polarized waves received by the first waveguides with each other, for trans-mitting the second circularly polarized wave thus combined; and converter means for converting into an intermediate fre~uency (IF) signal at least one of the first and second circularly polarized waves thus combined and transmitted through the second and third waveguides.
In the antenna apparatus according to the present invention described above, either one of the counterclockwise and clockwise circularly polarized waves received by the planar array antenna can be selected to be supplied to a tuner.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective view of a planar array antenna in a first embodiment according to the present invention;
Fig. 2 is a plan view of the planar array antenna in the first embodiment according to the present invention;
Fig. 3 is a plan view of a planar array antenna in a second embodiment according to the present invention;
Fig. 4 is a graph showing a relationship between the penetrating energy and antenna efficiency of the planar array antenna~ according to the present invention;
Fig. 5A is a plan view of a planar array antenna in a third embodiment according to the present invention;
Fig. 5B is a cross-sectional view of the planar array antenna in the third embodiment according to the present invention;
Fig. 6 is a schematic diagram of an antenna apparatus in a fourth embodiment according to the present invention;
Fig. 7 is a schematic diagram of an antenna apparatus in a fifth embodiment according to the present invention;
Fig. 8 is a schematic diagram of an antenna apparatus in a sixth embodiment according to the present ' ~ CA 02217730 1997-10-08 -invention;
Fig. 9 is a schematic diagram of an antenna apparatus in a seventh embodiment according to the present invention;
Fig. 10 is a schematic diagram of an antenna apparatus in an eighth embodiment according to the present invention;
Fig. llA is a plan view showing the overall configuration of the antenna apparatus according to the present invention;
Fig. llB is a side view showing the overall structure of the antenna apparatus according to the present invention;
Fig. 12A is a plan view of an antenna apparatus in a ninth embodiment according to the present invention;
Fig. 12B is a cross-sectional view of the antenna apparatus in the ninth embodiment according to the present invention;
Figs. 13A and 13B are plan views of an antenna apparatus in a tenth embodiment according to the present invention; and Fig. 14 is a plan view of a conventional planar array antenna for clockwise or counterclockwise circularly polarized waves.
BEST MODES OF CARRYING OUT THE INVENTION
Next, description will be given of an ~ CA 02217730 1997-10-08 >
embodiment of the present invention by referring to the drawings. Incidentally,~for convenience of explanation, description will be given of the wave radiating opera-tion of the antenna. However, according to the recipro-city theorem, it is to be understood that the antenna isalso applicable to the wave receiving operation.
Fig. 1 is a perspective view showing a first embodiment of a planar array antenna according to the present invention and Fig. 2 is a plan view of the antenna of Fig. 1. A feeding waveguide lA includes a feed opening 2A and branch openings 3A as guide means, whereas a feeding waveguide lB includes a feed opening 2B and branch openings 3B as guide means.
Respectively disposed in the neighborhood of the feed openings 2A and 2B are connecting or connector terminals 4A and 4B to establish connections via cables to external circuits. Each of the terminals 4A and 4B
includes a connector portion for the connection of the cable and a feed pin portion for the feeding of power to the antenna. In the connector portion, a cold side thereof is linked with a housing of the planar array antenna and a hot side thereof is coupled with the feed pin portion. Therefore, in a state in which the cable is connected to the connector, a cold side of the cable is liked with the housing of the antenna and a hot side thereof is coupled with the feed pin portion.
A plurality of radiating waveguides 11 arranged in parallel with each other are connected - ~ CA 02217730 1997-10-08 vertically to the feeding waveguides lA and lB via the branch openings 3A and 3B, respectively. In each of the radiating waveguides 11, there are disposed a plurality of cross-slots 12 to radiate circularly polarized waves.
Waves fed from the feed opening 2A are propagated through the feeding waveguide lA and are distributed in an equi-phase state via the branch openings 3A to the plural radiating waveguides 11 to be radiated as clock-wise circularly polarized waves from the cross-slots 12.
On the other hand, waves supplied from the feed opening 2B are passed through the feeding waveguide lB to be distributed in an in-phase state via the branch openings 3B to the plural radiating waveguides 11 so as to be radiated as counterclockwise circularly polarized waves from the cross-slots 12.
When the wave feeding operation is conducted respectively at both ends of the radiating waveguides 11 as described in relation to this embodiment, if there is employed a broad side array antenna in which the slots are disposed with an interval of guide wavelength ~g of the waveguide to radiate waves in front of the antenna, the antenna efficiency is remarkably lowered. This is because the guide wavelength ~g is larger than the free space wavelength ~0. That is, when the slot interval is greater than the free space wavelength ~0, there occurs a phenomenon called "grating robe" in which a side robe equal in the level to the main beam in the front direc-tion appears according to a fixed pattern in a wide - ~ CA 02217730 1997-10-08 angle.
To acquire a practical efficiency, it is necessary to configure a leaky wave array antenna in which the slots are tightly arranged with a small interval therebetween. In the antenna, the waves are radiated in a direction other than the front direction thereof. Namely, the radiating direction is tilted considerably toward the direction of axis of the feed waveguide. In consequence, the beam directions respec-tively of the counterclockwise and clockwise circularlypolarized waves are tilted in the mutually opposing directions and hence it is impossible, when the antenna is fixed, to receive both of the counterclockwise and clockwise circularly polarized waves. However, as described in Article 1, in a case in which the antenna attached, for example, on the roof of a car is rotated in a particular plane to follow a broadcasting satel-lite, the antenna is practical for the following reasons. Namely, since the elevation angles of these beams are the same to each other, when a change-over is required between the counterclockwise and clockwise circularly polarized waves, it is only necessary to rotate the antenna 180~ in the particular plane.
Fig. 3 is a plan view showing a second embodi-ment of the planar array antenna according to thepresent invention. This embodiment differs from the first embodiment in that the positions of slots are shifted between the adjacent waveguides 11 such that the - ' CA 02217730 1997-10-08 -phases respectively of the waves supplied thereto are opposite to each other. As described in an article "A
Waveguide Fed Printed Antenna", Transactions of IEICE of Japan, AP89-3, an advantage derived from the case in which the waves fed to the adjacent radiating waveguides are opposing in phase to each other resides in that the radiating waveguides can be constructed by attaching a groove-shaped structure onto a flat plate having slots therein and it is not necessarily required that the structure and the plate are completely tightly fixed to each other.
In a case in which the phases of the waves fed to the adjacent waveguides 11 are opposite to each other as shown in Fig. 3, when the leaky wave array antenna is employed, which leads to a reverse effect when compared with the case of Fig. 2, the waves emitted from the adjacent radiating waveguides have the mutually opposing phases and hence weaken each other. Namely, the radiation beams are not formed and the operation fails.
To overcome this difficulty, there will be considered the configuration of a broad side array antenna. For this purpose, radiating cross-slots 12 are arranged along the direction of axis of waveguides 11 with an interval of guide wavelength ~g such that between the adjacent waveguides 11, the position of each slot 12 is shifted ~g/2 in the direction of axis. Under this condition, when the waveguides 11 are filled with a dielectric substance the relative dielectric constant ~r of which is more than one, there is attained an advan-tage that the grating robe does not occur even if the broad side array antenna is employed, which differs from the case of Fig. 2. The reason therefor will be described. The grating robe occurs when the m~X; mum interval between the adjacent slot strings is greater than the free space wavelength ~0. In the antenna of Fig. 3, distance "h" indicates the m~Ximum interval.
Ignore the thickness of the wall of waveguide 11 and assume the width to be expressed as "a". Then, distance "h" is represented by the following expression:
~g : h = ( ) : a ............................ (1) On the other hand, it is well known that guide wavelength ~g of waveguide 11 is denoted as follows when waves are transmitted in a basic mode, TE10 mode.
= ... (2) / ( ~ )2 where, ~ is a wavelength in the dielectric and is represented as follows-Ao ;~ r ~ . ( 3 ) Simplifying expressions (1) and (2), distance"h" is finally equal to ~. Therefore, when relative inductivity ~r is slightly larger than one, h < ~0 holds and hence the grating robe does not take place. Addi-tionally, when the change in relative inductivity with respective to temperature and the like are taken into consideration, the value of relative inductivity is desirably at least about 1.1.
Since the planar array antenna of the embodi-ment is a broad side array antenna, the same radiating direction can be set for the counterclockwise and clockwise circularly polarized waves. In consequence, when the reception signal is desired to be switched between the counterclockwise and clockwise circularly polarized waves, it is unnecessary to turn the antenna.
Subsequently, description will be given of a high efficiency in practices of the planar array antenna according to the first or second embodiment.
In general, the efficiency of the planar array antenna takes the m~imum value when the radio wave , radiated from each radiation slot has the same ampli-tude. This condition is satisfied in the array antenna for the counterclockwise or clockwise circularly polarized waves by adjusting the length and positions of the slots along the axis of waveguides. Theoretically, the efficiency therefore becomes 100%.
In contrast therewith, according to the planar array antenna of the present invention, waves are fed from both sides of the radiating waveguides 11. When the antenna is designed such that the slot radiation becomes uniform for the waves fed from a first side of the waveguides 11, the slot radiation for the waves supplied from a second side opposing to the first side develops a distribution with a large gradient and hence the efficiency is remarkably lowered. In a simplest model in which there are arranged slots each having the same contour, waves are radiated from each slot with a fixed ratio and the remained energy penetrates through the waveguides 11 to be absorbed by the feeding wave-guide on the opposite side which is not in the feedingoperation.
Fig. 4 is a graph showing the calculated results of antenna efficiency obtained by changing the ratio of the penetrating energy. When the penetrating energy, i.e., the loss is about 8%, the antenna effici-ency takes the m~;mum value of about 81%. The effici-ency is higher than that of the radial line slot antenna described in Article 2 or the parabola antenna used in ' . CA 02217730 1997-10-08 >
practices today and hence this value is fully satis-factory for practical uses. The reason why the planar array antenna of the present invention has a higher efficiency when compared with the antenna described in Article 2 is as follows.
In the radial line slot antenna, the behavior of waves including an inward oriented cylindrical wave and an outward oriented cylindrical wave transmitted through the radiating radial waveguides is utilized to achieve the radiation of the counterclockwise and clockwise circularly polarized waves. In consequence, there is missing a condition under which the efficiency is increased for both of the counterclockwise and clockwise circularly polarized waves. In comparison therewith, the antenna according to the present inven-tion includes radiating waveguides having a uniform cross section like square waveguides. Consequently, the waves propagated through the waveguide in either direc-tions conduct substantially the same behavior. Accord-ingly, when the slots are symmetrically arranged withrespect to an intermediate point of the radiating waveguide, the condition of m~x;mllm efficiency for the counterclockwise circularly polarized waves becomes almost equal to that of ~ximum efficiency for the clockwise circularly polarized waves, which results in a high efficiency.
Next, description will be given of a third embodiment of the planar array antenna according to the present invention. Although the array antenna includes waveguides in the embodiments described above, the present invention is not restricted by the embodiments.
Namely, in place of the waveguides, there may be adopted micro-strip lines, strip lines, co-planar lines, slot lines, parallel flat plate lines, flat plane lines such as dielectric surface wave lines. Figs. 5A and 5B show the third embodiment of the planar array antenna employ-ing strip lines. Fig. 5A shows a plan view of the antenna and Fig. 5B is a cross-sectional view thereof taken along a line A-A of Fig. 5A. In a space enclosed with a conductive plate 33 and a conductive case 34, there are arranged two dielectric substrates 35 and 36 between which strip lines are configured. This configu-ration includes three conductors with two dielectricbodies therebetween and hence is called "tri-plate structure". The strip lines include a plurality of radiating lines 31 formed parallel to each other and distributing circuits 21A and 21B to supply signals to these lines 31 from both sides thereof. In addition, there are provided connector terminals 24A and 24B to respectively connect the circuits 21A and 21B to external circuits. In the conductor plate 33 opposing the radiating lines 31, there are disposed a plurality of circularly polarized wave radiating slots 32, each slot 32 including a pair of linear slots which are not parallel to each other.
The signal applied to the terminal 24A is ~ CA 02217730 1997-10-08 >
passed through the distributing circuit 21A to be fed in an in-phase state to the plural radiating lines 31 so as to be radiated as counterclockwise circularly polarized waves from the slots 32. On the other hand, the signal fed to the terminal 24B is emitted as clockwise circu-larly polarized waves from the pertinent slots 32.
In the first to third embodiments above, cross-slots and non-parallel slots are described as examples of the circularly polarized wave radiating slots. However, it is to be appreciated that the present invention is applicable to slots having other contours. Additionally, the shapes of the feeding wave-guide and the distributing circuit are not restricted by the embodiments. Namely, it is only necessary for the feeding waveguide and the distributing circuit to supply signals to the radiating waveguides or lines in a parallel fashion. Moreover, when planar lines are employed, a planar array antenna capable of radiating the counterclockwise and clockwise circularly polarized waves can be implemented using strip dipoles which electromagnetically has a complementary relationship with respect to the slots.
Next, description will be given of an antenna apparatus using such a planar array antenna as those described in the embodiments above. Figs. llA and llB
respectively are a plan view and a side view showing the overall configuration of the apparatus. However, for easy understanding of the inner configuration, a radome . CA 02217730 1997-10-08 as the cover is missing in Fig. llA and the radome is cut at the central portion thereof in Fig. llB. As means for rotating the antenna, there are provided a rotating unit 71 in a lower portion of the planar array antenna 41, a belt 72, a decelerator 73, a motor 74 and a motor drive circuit in a fixed-side circuit unit 75.
Furthermore, reference numeral 76 denotes a rotary-side circuit unit. The elevation angle of the antenna 41 is adjusted by an EL driver unit 77 and an EL motor 78.
Additionally, the rotating unit 71 includes slip rings arranged to transmit power and control signals to a rotary-side circuit unit 76, the EL motor 78, and con-verters 42A and 42B. These components are mounted on the base plate 79 and are covered with a radome 80.
Fig. 6 is a schematic diagram showing a fourth embodiment of the antenna apparatus according to the present invention. This apparatus includes a planar array antenna 41 which is similar to the antenna shown in the first embodiment and which is ratably attached, for example, on a roof of an automobile; converters 42A
and 42B connected respectively via connector terminals 4A and 4B to the antenna 41, capacitors 43A and 43B
respectively connected to the converters 42A and 42B to suppress direct-current (DC) components, a rotary coupler 44 electrically equivalent to a capacitor, and a tuner 45. In addition, a DC power source 49 is con-nected to the converterS 42A and 42B via switch circuits 48A and 48B either one of which is turned on by the ~ ~ CA 02217730 1997-10-08 control circuit 46, interference preventing resistors 47A and 47B, and/or slip rings arranged in the rotary unit 71 as shown in Fig. llB. When the DC voltage is applied to the signal output line, the converters 42A
and 42B down convert an RF (radio frequency) signal of satellite broadcasting from the antenna 41 into an IF
(intermediate frequency) signal. According to supplied information representing desired one of polarized waves, the control circuit 46 turns either one of the switch circuits 48A and 48B on, the switch circuit being on the side of the desired one of the circularly polarized waves. In consequence, according to the present embodi-ment, since only the intermediate frequency signal output from either one of the converters 42A and 42B to which the DC voltage is=applied is input to the tuner 45, it is possible to select the desired one of the polarized waves. In this connection, the number of capacitors may be reduced ~y configuring the capacitors 43A and 43B with rotary couplers in place of the rotary coupler 44.
Furthermore, when the switch circuits are disposed in the signal lines, not in the power source lines, as shown in the flfth embodiment as shown in Fig.
7, the desired one of the polarized waves can be selected. In Fig- 7, two intermediate frequency signals output from the converters 42A and 42B are respectively fed via the DC suppressing capacitors 51A and 51B such that either one thereo~is selected by the switch 52 to ~ ~ CA 02217730 1997-10-08 be input to the tuner 45- On the other hand, the DC
voltage is supplied to the converters 42A and 42B.
Incidentally, rotary couplers are not shown in this embodiment because rotary couplers may be used as the DC
suppressing capacitors 51A and 51B. Alternatively, a rotary coupler may be arranged between the switch 52 and the tuner 45.
In the antenna apparatus as shown in Figs. 6 and 7, although the signal line of the converters 42A or 42B also serves as the power line, there may also be utilized converters of which these lines are separately provided.
In the sixth embodiment as shown in Fig. 8, intermediate frequency signals output from two converters 42A and 42B are linked with a rotary coupler 53 to be supplied therethrough to a tuner 45. Only the intermediate frequency signal output from either one of the converters 42A and 42B to which the DC voltage is applied is actually input to the tuner. Resultantly, there can be selected the desired one of the circularly polarized waves.
In addition, according to the seventh embodi-ment as shown in Fig- 9 L intermediate frequency signals sent from two converters 42A and 42B are acquired respectively via DC suppressing capacitors 51A and 51B
such that either one thereof is selected by a switch circuit 52 to be delivered to a tuner 45. On the other hand, the DC voltage is applied to the converters 42A
- ' CA 02217730 1997-10-08 and 42B. In this regard, rotary couplers are not shown in this embodiment, because rotary couplers may be used as the DC suppressing capacitors 51A and 51B. Or, rotary couplers may be provided between the switch 52 and the tuner 45. With this provision, it is possible to desirably select either one of the circularly polarized wave.
In the antenna facilities as shown in Figs. 6 to 9, although the counterclockwise or clockwise circu-larly polarized wave is selected through an electricswitching operation, the wave selection may also be conducted by altering the antenna direction.
The eighth embodiment of the present invention as shown in Fig. 10 includes antenna rotating means 63 to turn the planar array antenna 41 attached onto a roof of a car or the like. The means 63 includes a rotary unit 71, a belt 72, a decelerator 73, a motor 74, and a motor drive circuit in a fixed-side circuit unit 75 as shown in Fig. llB.
Referring to Fig. 10, two intermediate frequency signals produced from converters 42A and 42B
applied with the DC voltage are added to each other by adder means 61 to be fed via a rotating coupler 53 to a tuner 45. In this connection, the adder means 61 may be implemented, if the circuit configuration thereof is acceptable, by simply linking the outputs from the converters 42A and 42B with each other. On receiving polarized wave information denoting desired one of the circularly polarized waves and polarized wave informa-tion indicating a reception channel from the tuner 45, a control circuit 62 in the fixed-side circuit unit 75 decides whether or not these information items match with each other. If mismatching results, the controller 62 outputs a control signal to the antenna rotating means 63. In response to the signal, the means 63 turns the antenna 41 about 180 to thereby select the desired one of the polarized waves.
Referring now to Figs. 12A and 12B, descrip-tion will be given of the antenna apparatus in the ninth embodiment according to the present invention. Fig. 12A
is a plan view of the apparatus in which an upper sur-face unit (81 in Fig. 12B) having a plurality of slots is missing. Fig. 12B is a cross-sectional view of the antenna facility taken along line B-B of Fig. 12A. In this embodiment, a transmission unit 83 is arranged in a lower portion of an antenna body 82 so that the antenna can be operated only with one converter 85. In other words, the feed opening of the feeding waveguide as shown in the first embodiment is provided on the lower side, and the transmission unit 83 serving as a wave-guide is integrally fabricated therewith or is connected thereto. As a result, the feed openings on both sides of the antenna are linked with each other. Consequ-ently, for the counterclockwise and clockwise circularly polarized waves, the energy thereof can be radiated or received via a connector t~rm;n~l 84 with the single converter 85.
Subsequently, description will be given of the planar array antenna in the tenth embodiment according to the present invention by referring to Figs. 13A and 13B. In these diagrams, i.e., plan views of the antenna, an upper portion having a plurality of slots is missing for easy understanding of the structure. In this embodiment, inductive posts 93A and 93B of Fig. 13A
or inductive walls 94A and 94B of Fig. 13B are fabri-cated in the vicinity of branch openings 3A and 3B of afeeding waveguide to thereby m;nimi ze reflection of waves. The reflection minimi zing effect of inductive posts or walls has been described in detail in article "An Analysis of a Waveguide ~ Junction with an Inductive Wall", 1994 Spring Conference of IEICE of Japan, B-54 and in article "Characteristics of Single-Layer ~- and T-Junction with Inductive Wall", 1995 General Conference of IEICE of Japan, B-83. The inductive posts 93A and 93B can be attached after the antenna body 92 is comp-letely fabricated. Additionally, when the inductive walls 94A and 94B as well as the antenna body 92 are manufactured at the same time, the post-process will be unnecessary.
In the embodiments above, the connector terminals 4A and 4B are disposed in the proximity respectively of the feed openings 2A and 2B such that waves are communicated via a cable between the antenna body and the converter.- However, the present invention is not restricted by the embodiments, namely, the wave communication may be carried out in the following configurations.
First, the feed openings are each constructed in the form of a standard opening of waveguide, e.g., in conformity with the standard WR-75. In this structure, the input side of the converter is required to conform to the standard opening of waveguide. In short, the feed openings are used to pass waves therethrough.
Furthermore, only the feed pin sections of connector terminals 4A and 4B may be arranged in the feeding section of the converter in some cases. In this configuration, the cable is unnecessary. The feed openings function in the same way as for the construc-tion including the connector terminals 4A and 4B of the embodiments, namely, the opening is used to pass there-through the connector portions of the connector terminals.
In addition, although the connector terminals 4A and 4B or the connector terminal 84 are or is employed to couple the planar array antenna with the converter, the connection therebetween may be established without using the connector terminal(s) as described above.
INDUSTRIAL APPLICABILITY
As above, the planar array antenna according to the present invention is useful to transmit or to ' CA 02217730 1997-10-08 receive both of the counterclockwise and clockwise circularly polarized waves with a high efficiency.
Claims (18)
1. A planar array antenna, comprising:
a plurality of first waveguides arranged with axes thereof mutually in parallel to each other, each of the first waveguides having a plurality of slots at predetermined positions to radiate or to receive circularly polarized waves; and two second waveguides having axes of waveguide vertical to a direction of axes of the first waveguides and respectively connected via junction openings to both ends of the first waveguides, the second waveguides being on a plane on which the first waveguides exist and having feed openings respectively;
wherein both counterclockwise and clockwise circularly polarized waves are radiated or received through each of the slots of the first waveguides via the feed openings of the second waveguides.
a plurality of first waveguides arranged with axes thereof mutually in parallel to each other, each of the first waveguides having a plurality of slots at predetermined positions to radiate or to receive circularly polarized waves; and two second waveguides having axes of waveguide vertical to a direction of axes of the first waveguides and respectively connected via junction openings to both ends of the first waveguides, the second waveguides being on a plane on which the first waveguides exist and having feed openings respectively;
wherein both counterclockwise and clockwise circularly polarized waves are radiated or received through each of the slots of the first waveguides via the feed openings of the second waveguides.
2. (Deleted).
3. A planar array antenna connected to at least one converter, comprising:
a plurality of first waveguides arranged with axes thereof mutually in parallel to each other, each of the first waveguides having a plurality of slots at predetermined positions to receive both a first circularly polarized wave and a second circularly polarized wave;
a second waveguide, including a plurality of guide sections for combining the first circularly polarized waves received by the first waveguides with each other, for transmitting the first circularly polarized wave thus combined to the at least one converter; and a third waveguide, including a plurality of guide sections for combining the second circularly polarized waves received by the first waveguides with each other, for transmitting the second circularly polarized wave thus combined to the at least one converter;
wherein the second and third waveguides are on a plane on which the first waveguides exist.
a plurality of first waveguides arranged with axes thereof mutually in parallel to each other, each of the first waveguides having a plurality of slots at predetermined positions to receive both a first circularly polarized wave and a second circularly polarized wave;
a second waveguide, including a plurality of guide sections for combining the first circularly polarized waves received by the first waveguides with each other, for transmitting the first circularly polarized wave thus combined to the at least one converter; and a third waveguide, including a plurality of guide sections for combining the second circularly polarized waves received by the first waveguides with each other, for transmitting the second circularly polarized wave thus combined to the at least one converter;
wherein the second and third waveguides are on a plane on which the first waveguides exist.
4. (Deleted).
5. A planar array antenna according to Claim 3, wherein:
the antenna is connected to one converter disposed at a position apart from the first waveguides;
the second waveguide further includes first transmission means for transmitting the first circularly polarized wave thus combined to the converter; and the third waveguide further includes second transmission means for transmitting the second circularly polarized wave thus combined to the converter.
the antenna is connected to one converter disposed at a position apart from the first waveguides;
the second waveguide further includes first transmission means for transmitting the first circularly polarized wave thus combined to the converter; and the third waveguide further includes second transmission means for transmitting the second circularly polarized wave thus combined to the converter.
6. A planar array antenna according to Claim 3, wherein:
the first circularly polarized wave is a counterclockwise circularly polarized wave; and the second circularly polarized wave is a clockwise circularly polarized wave.
the first circularly polarized wave is a counterclockwise circularly polarized wave; and the second circularly polarized wave is a clockwise circularly polarized wave.
7. A planar array antenna according to Claim 3, wherein the plurality of slots are cross-slots.
8. A planar array antenna according to Claim 3, wherein the plurality of slots are arranged on one side of each of the first waveguides.
9. A planar array antenna according to claim 3, wherein the plurality of slots have the same offset relative to the waveguide axis.
10. A planar array antenna according to Claim 3, wherein the plurality of slots are arranged in the direction of waveguide axis with an interval therebetween, the interval being substantially equal to a guide wavelength of the first and second circularly polarized waves.
11. An antenna apparatus including a planar array antenna for receiving waves of satellite broadcasting, comprising:
a plurality of first waveguides arranged with axes thereof mutually in parallel to each other, each of the first waveguides having a plurality of slots at predetermined positions to receive a first circularly polarized wave and a second circularly polarized wave;
a second waveguide, including a plurality of guide sections for combining the first circularly polarized waves received by the first waveguides with each other, for transmitting the first circularly polarized wave thus combined;
a third waveguide including a plurality of guide sections for combining the second circularly polarized waves received by the first waveguides with each other, for transmitting the second circularly polarized wave thus combined; and converter means for converting into an intermediate frequency (IF) signal at least one of the first and second circularly polarized waves thus combined and transmitted through the second and third waveguides.
a plurality of first waveguides arranged with axes thereof mutually in parallel to each other, each of the first waveguides having a plurality of slots at predetermined positions to receive a first circularly polarized wave and a second circularly polarized wave;
a second waveguide, including a plurality of guide sections for combining the first circularly polarized waves received by the first waveguides with each other, for transmitting the first circularly polarized wave thus combined;
a third waveguide including a plurality of guide sections for combining the second circularly polarized waves received by the first waveguides with each other, for transmitting the second circularly polarized wave thus combined; and converter means for converting into an intermediate frequency (IF) signal at least one of the first and second circularly polarized waves thus combined and transmitted through the second and third waveguides.
12. An antenna apparatus according to Claim 11, further comprising control means for controlling the converter means such that the antenna receives only the first or second circularly polarized wave.
13. An antenna apparatus according to Claim 12, wherein:
the converter means includes a first circuit for converting into a first intermediate frequency signal the first circularly polarized wave thus combined and transmitted through the second waveguide and a second circuit for converting into a second intermediate frequency signal the second circularly polarized wave thus combined and transmitted through the third waveguide; and the control means includes means for supplying power to selected one of the first and second circuits.
the converter means includes a first circuit for converting into a first intermediate frequency signal the first circularly polarized wave thus combined and transmitted through the second waveguide and a second circuit for converting into a second intermediate frequency signal the second circularly polarized wave thus combined and transmitted through the third waveguide; and the control means includes means for supplying power to selected one of the first and second circuits.
14. An antenna apparatus according to Claim 12, wherein:
the converter means includes a first circuit for converting into a first intermediate frequency signal the first circularly polarized wave thus combined and transmitted through the second waveguide and a second circuit for converting into a second intermediate frequency signal the second circularly polarized wave thus combined and transmitted through the third waveguide; and the control means includes means for selecting either one of the output signals respectively from the first and second circuits.
the converter means includes a first circuit for converting into a first intermediate frequency signal the first circularly polarized wave thus combined and transmitted through the second waveguide and a second circuit for converting into a second intermediate frequency signal the second circularly polarized wave thus combined and transmitted through the third waveguide; and the control means includes means for selecting either one of the output signals respectively from the first and second circuits.
15. An antenna apparatus according to Claim 11, further comprising:
antenna rotating means for rotating at least the first to third waveguides such that the first waveguides receive either one of the first and second circularly polarized waves; and control means for deciding whether or not the circularly polarized wave received by the first waveguides is a desired circularly polarized wave and controls the antenna rotating means, when the received wave is other than the desired wave, such that the first waveguides receive the desired circularly polarized wave.
antenna rotating means for rotating at least the first to third waveguides such that the first waveguides receive either one of the first and second circularly polarized waves; and control means for deciding whether or not the circularly polarized wave received by the first waveguides is a desired circularly polarized wave and controls the antenna rotating means, when the received wave is other than the desired wave, such that the first waveguides receive the desired circularly polarized wave.
16. An antenna apparatus according to Claim 11, further comprising a housing to be mounted on a mobile body.
17. An antenna apparatus according to Claim 11, wherein the guide section is an opening section.
18. A planar array antenna according to Claim 3, wherein the guide section is an opening section.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/JP1996/000572 WO1997033342A1 (en) | 1996-03-08 | 1996-03-08 | Planar array antenna |
| CA002217730A CA2217730A1 (en) | 1996-03-08 | 1996-03-08 | Planar array antenna |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/JP1996/000572 WO1997033342A1 (en) | 1996-03-08 | 1996-03-08 | Planar array antenna |
| CA002217730A CA2217730A1 (en) | 1996-03-08 | 1996-03-08 | Planar array antenna |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2217730A1 true CA2217730A1 (en) | 1997-09-12 |
Family
ID=25679701
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002217730A Abandoned CA2217730A1 (en) | 1996-03-08 | 1996-03-08 | Planar array antenna |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2217730A1 (en) |
| WO (1) | WO1997033342A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104604027A (en) * | 2012-06-19 | 2015-05-06 | 罗伯特·博世有限公司 | Antenna arrangement and method |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7339520B2 (en) * | 2000-02-04 | 2008-03-04 | The Directv Group, Inc. | Phased array terminal for equatorial satellite constellations |
| US7068733B2 (en) | 2001-02-05 | 2006-06-27 | The Directv Group, Inc. | Sampling technique for digital beam former |
| EP2245704B1 (en) | 2007-12-28 | 2015-02-18 | SELEX ES S.p.A. | Slot antenna and method for operating the same |
| CN106711576B (en) * | 2016-12-14 | 2019-10-25 | 西安电子科技大学 | Integrated solar cell and slot antenna device |
| JP6752396B2 (en) * | 2018-05-14 | 2020-09-09 | 三菱電機株式会社 | Array antenna device |
| CN110034386B (en) * | 2019-03-26 | 2020-10-23 | 北京遥测技术研究所 | Low-axis-ratio high-efficiency wide-angle scanning waveguide slot linear array antenna |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5496389A (en) * | 1978-01-17 | 1979-07-30 | Toshiba Corp | Radar device |
| JPS6236906A (en) * | 1985-08-09 | 1987-02-17 | Sharp Corp | Dual polarization antenna system |
| JP2641544B2 (en) * | 1988-12-13 | 1997-08-13 | 新日本製鐵株式会社 | Attitude control method and apparatus for receiving antenna |
| JPH02186703A (en) * | 1989-01-13 | 1990-07-23 | Naohisa Goto | Slot array antenna of waveguide |
| JPH03169103A (en) * | 1989-11-28 | 1991-07-22 | Matsushita Electric Ind Co Ltd | Circular polarization receiver |
| JPH03169104A (en) * | 1989-11-28 | 1991-07-22 | Matsushita Electric Ind Co Ltd | Circularly polarized/linearly polarized antenna equipment and transmitter/receiver equipment |
| JPH0654844B2 (en) * | 1989-12-04 | 1994-07-20 | デイエツクスアンテナ株式会社 | Planar antenna |
| JP2582472B2 (en) * | 1990-10-08 | 1997-02-19 | 日本電気株式会社 | Dual-polarized antenna |
| JP2526393B2 (en) * | 1991-07-12 | 1996-08-21 | 東京工業大学長 | Parallel plate slot antenna |
| JPH0878948A (en) * | 1994-09-08 | 1996-03-22 | Nippon Steel Corp | Leaky wave waveguide cross slot array antenna |
-
1996
- 1996-03-08 CA CA002217730A patent/CA2217730A1/en not_active Abandoned
- 1996-03-08 WO PCT/JP1996/000572 patent/WO1997033342A1/en not_active Ceased
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104604027A (en) * | 2012-06-19 | 2015-05-06 | 罗伯特·博世有限公司 | Antenna arrangement and method |
| US9912054B2 (en) | 2012-06-19 | 2018-03-06 | Robert Bosch Gmbh | Antenna array and method |
| CN104604027B (en) * | 2012-06-19 | 2018-09-25 | 罗伯特·博世有限公司 | Antenna assembly and method |
Also Published As
| Publication number | Publication date |
|---|---|
| WO1997033342A1 (en) | 1997-09-12 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |