JP3405233B2 - Waveguide branch circuit and antenna device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide branch circuit for distributing or synthesizing electric power propagated by electromagnetic waves in a high frequency band such as microwaves and millimeter waves, and a radiating element having a predetermined length in the waveguide longitudinal direction. The present invention relates to a waveguide array antenna for transmission or reception having array planes arranged at intervals.

[0002]

2. Description of the Related Art A waveguide branch circuit that distributes or combines electric power propagated by electromagnetic waves in a high frequency band such as microwaves and millimeter waves, and radiating elements are arranged at predetermined intervals in the longitudinal direction of the waveguide. As the waveguide slot array antenna having an array surface, those described in "Japanese Patent Laid-Open No. 5-3405: Waveguide coupling structure" are known. In these waveguide slot array antennas, a set of two waveguide slot array antennas are arranged as a sub array antenna, and slot-shaped radiating elements are provided at predetermined intervals to reduce the width of the waveguide. The waveguides are joined so that the surfaces are in close contact with each other. For this reason, the phase center interval between the sub-array antennas has become larger than the free space wavelength λ _{0 of the} electromagnetic wave, and there has been a problem that unwanted radiation called a grating lobe is generated.

FIG. 13 is a perspective view of another conventional waveguide slot array antenna 900. In the present antenna 900, the waveguides are joined so that the wide surfaces of the waveguides are in close contact with each other, and a two-branch circuit 910 is provided for each pair of two waveguide slot array antennas (sub array antennas) 920.
More power is distributed and fed. Therefore, this antenna 9
In No. 00, unlike the case of the waveguide slot array antenna described in "JP-A-5-3405: Waveguide coupling structure", slot-shaped radiating elements 6 are arranged on the narrow surface of the waveguide. The array surface is used. Therefore, this antenna 90
At 0, the phase center spacing S between the sub array antennas 920 is S.
_{The y} can be set to be the free space wavelength λ ₀ or less of the electromagnetic wave. With this configuration, in the present antenna 900, y
On the z plane, the angle θ from the z axis is “0 <θ ≦ π /
No grating lobes are generated in the direction of "2".

[0004]

However, when constructing such an antenna, since the width of each waveguide in the y-axis direction is narrower than the width in the z-axis direction, the electric field is directed in the y-axis direction. Will end up. For this reason, the distribution power supply means using the power supply probe (metal pin) and the distribution power supply means using the T-shaped coupling slot described in "Japanese Patent Laid-Open No. 5-3405: Waveguide Coupling Structure" should be used. There is a new problem that is impossible.

Therefore, in the prior art, when power is fed to the antenna 900 as shown in FIG. 13 from the back side for every two waveguides, the E-plane branching device 91 as shown in FIG. 14 is used.
It was not possible without using the two-branch circuit 910 which is a power feeding circuit in which 1 and the H-plane vent 912 were combined. However, since such a two-branch circuit 910 has a complicated shape, it is difficult to mass-produce or downsize it.

When distributed power is supplied by the two-branch circuit 910, since electromagnetic waves are supplied to the two rows of waveguides to be distributed and supplied in the same phase, when the beam direction is directed to the z-axis direction, the x-axis is used. It is necessary to match the array period S _x of the radiating elements 6 arranged in the direction with the wavelength λ ₁ in one waveguide of this electromagnetic wave. At this time, since “λ ₀ <λ ₁ = S _x ”, xz
There is a problem that a grating lobe occurs in a direction in which the angle θ from the z axis on the plane satisfies the following expression (1).

## EQU1 ## λ ₀ = S _x sin θ (0 <θ ≦ π / 2) (1)

The present invention has been made to solve the above problems, and an object of the present invention is, for example, a waveguide array antenna 900, in which the width of the waveguide in the y-axis direction is the z-axis. It is an object of the present invention to provide a waveguide branch circuit which is capable of distributed power feeding to two waveguides having a width less than or equal to the direction, is easy to mass-produce and downsize, and has good energy efficiency. A further object of the present invention is to provide an antenna in which no grating lobe is generated in any direction.

[0008]

In order to solve the above-mentioned problems, the following means are effective. That is, the first means is a waveguide branch circuit that distributes the power supplied from the sub-waveguide to two waveguides arranged close to each other and parallel to each other. A matching wall parallel to the central axis extending perpendicularly from the top surface of the waveguide branch circuit parallel to the reference surface including each center axis of the waveguide and facing the top surface with the reference surface sandwiched. A substantially rectangular or substantially elliptical coupling window whose longitudinal direction is perpendicular to the matching wall, the coupling window being provided on the coupling surface on the waveguide branch circuit; Is to bond to the bonding surface perpendicular to the bonding surface so as to cover.

The second means is a U-shaped or U-shaped curved waveguide for connecting the respective openings on the same side of the two waveguides to each other in the above-mentioned first means. And providing the coupling window on the coupling surface on the curved waveguide to distribute the power to the two branches.

A third means is the same as the first means, except that the coupling window is formed on the coupling surface on the two waveguides.
This is to distribute the above power to the four branch paths by providing it across the two waveguides and further providing a communication port on the surface where the two waveguides are joined.

Further, the fourth means has an array surface in which the radiating elements are arranged at a predetermined interval in the longitudinal direction of the waveguide and are constituted by a plurality of waveguides arranged close to each other and parallel to each other. In the waveguide array antenna for transmission or reception, the waveguide lengths are provided on the top surface side of each of the two waveguides of the waveguide branch circuit of any one of the first to third means. A total of two rows of radiating elements are arranged in parallel in the direction, and a waveguide branch circuit is used in which the two rows of radiating elements are shifted from each other by approximately 1/2 guide wavelength of an electromagnetic wave propagating power. Forming the array structure of the radiating elements. The above-mentioned problems can be solved by the above means.

[0012]

In any of the first to fourth means of the present invention, the waveguide branch circuit has a simple structure and can be easily constructed from a small number of parts having a simple shape. A waveguide branch circuit that can be easily mass-produced and miniaturized can be configured.

Further, since it has an alignment wall extending perpendicularly from the top surface and parallel to the central axis, and a coupling window of a substantially rectangular or elliptical shape whose longitudinal direction is perpendicular to this alignment wall, FIG.
It is possible to configure a waveguide branch circuit capable of distributed power supply to two waveguides whose width in the y-axis direction is equal to or less than the width in the z-axis direction as illustrated in FIG.

The height H of the matching wall with respect to the distance H ₀ between the top surface and the coupling surface, the longitudinal length A of the coupling window with respect to the width A ₀ of the wide surface of the sub-waveguide, and the sub-wavelength By optimally adjusting each value of the width B _{0 of the} coupling window with respect to the width B _{0 of the} narrow surface of the waveguide, a waveguide branch circuit with high energy efficiency can be constructed.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on specific embodiments. (First Embodiment) FIG. 1 shows perspective views (a) and (b) of a waveguide branch circuit 100 in this embodiment. The waveguide branch circuit 100 distributes the electric power supplied from the sub-waveguide 3 to the two waveguides 1-A and 1-B arranged close to each other and parallel to each other. is there. These two waveguides 1-
The reference plane I including the central axes of A and 1-B is parallel to the xy plane, and the matching wall 5 extends vertically from the top surface J on the waveguide branch circuit parallel to the reference plane I. ing.

The matching wall 5 has two waveguides 1-
It is provided parallel to the central axes of A and 1-B. On the other hand, the waveguide branch circuit 10 facing the top surface J with the reference plane I interposed therebetween.
The other plane on 0 is called the coupling plane K. On this binding surface K,
A rectangular coupling window 4 whose longitudinal direction is perpendicular to the matching wall 5 is provided, and one opening of the sub-waveguide 3 is perpendicular to the coupling surface K so as to cover the coupling window 4. Are combined.

The respective openings on the same side of the two waveguides 1-A and 1-B are connected to each other by a curved waveguide 2 having a U-shaped inner surface and a U-shaped outer surface. The coupling window 4 is provided on the coupling surface K on the curved waveguide 2. With the above configuration, the power supplied from the sub-waveguide 3 is distributed to the two branch paths (waveguides 1-A and 1-B).

FIG. 2 is a sectional view (a) and (b) of the waveguide branch circuit 100. In the waveguide branch circuit 100, the height H of the matching wall 5 with respect to the distance H ₀ between the top surface J and the coupling surface K, and the coupling window 4 with respect to the width A ₀ of the wide surface of the sub-waveguide 3 are used. Of the waveguide with good energy efficiency by optimally adjusting the respective values such as the length A in the longitudinal direction of B, or the width B of the coupling window 4 with respect to the width B ₀ of the narrow surface of the sub-waveguide 3. It constitutes a branch circuit. That is, empirically through a large number of experiments, by adjusting these values H, A, and B optimally, the electric power supplied from the sub-waveguide 3 is adjusted to two waveguides 1.
Equal distribution can be efficiently made between -A and 1-B.

FIG. 3 shows the matching wall 5 of the waveguide branch circuit 100.
The explanatory view showing the action of is shown. When the matching wall 5 is not provided, a part of the electromagnetic wave supplied to the curved waveguide 2 from the feeding port (not shown) via the sub-waveguide 3 is part of the ceiling of the curved waveguide 2. The light is reflected by the facing surface J or the coupling surface K and returned to the power supply port (not shown). However, in the waveguide branch circuit 100, the matching wall 5 is provided as shown in FIG. 3, and the height H thereof is set so that the reflected waves in the figure cancel each other out of phase. Therefore, the power loss due to these reflected waves is significantly suppressed.

FIG. 4 is a vertical cross section of the sub-waveguide 3 and the coupling window 4.
Characteristics of the waveguide branch circuit 100 when the shape is congruent (A = A ₀ , B = B ₀ ) (relative to the amount of reflection viewed from the sub-waveguide 3 side) (Value) is a graph showing. As can be seen from this graph (FIG. 4), the reflection loss is lowest when the value of H / H ₀ is around 0.2 to 0.4. That is, it is understood that the reflection characteristics can be improved by the action of the matching wall 5.

5 and 6 show the reflection characteristics (relative value of the reflection amount viewed from the side of the sub-waveguide 3) according to the length A and the width B of the coupling window 4 of the waveguide branch circuit 100 in the longitudinal direction. It is a graph shown. By changing these dimensions A and B, an inductive component and a capacitive component are generated in the electromagnetic wave inside the sub-waveguide 3, respectively, and the imaginary part of the input impedance at the feeding point can be changed. .

Therefore, by optimizing the inductive component and the capacitive component, the reflection loss can be improved as shown in the figure. That is, FIG. 5 shows that the reflection loss is most reduced when A = A ₀ . In addition, in FIG.
/ B ₀ indicates that the reflection characteristic (the relative value of the reflection amount viewed from the side of the sub-waveguide 3) is −20 dB or less in the vicinity of 0.6 to 0.7. The loss due to reflection at this time was 1% or less. That is, it is understood that the power loss is significantly improved by the effects of these optimizations.

FIG. 7 is a graph showing the reflection characteristic of the waveguide branch circuit 100 designed with the frequency of the electromagnetic wave propagating the electric power as f ₀ , according to the frequency f of the actual electromagnetic wave supplied from the power supply port (not shown). is there. In this graph (FIG. 7), the dimensions of the waveguide branch circuit 100 are A / A ₀ = 1 and
The reflection characteristic (relative value of the reflection amount viewed from the sub-waveguide 3 side) was measured with B / B ₀ = 0.63 and H / H ₀ = 0.39. From this graph, in the vicinity of f = f ₀ , the reflection characteristic (relative value of the reflection amount viewed from the sub-waveguide 3 side) is −20d.
It turns out that it becomes B or less. The loss due to reflection at this time was 1% or less.

Under these conditions, the amount of transmission from the sub-waveguide 3 to each of the waveguides 1-A and 1-B is-
It is known that it is ideally evenly distributed with almost no loss of 3 dB. Further, the phase of the electromagnetic wave equally distributed to the waveguides 1-A and 1-B is opposite to the phase because the matching wall 5 and the coupling window 4 are orthogonal to each other as shown in FIG. Become.

The matching wall 5 does not necessarily have to be on the boundary surface between the waveguide 1-A and the waveguide 1-B. Matching wall 5
Can be translated in the y-axis direction of FIG. 1B to form a non-uniform distribution waveguide branch circuit.

(Second Embodiment) FIG. 8 is a perspective view (a), (b) of the antenna device 102, 101 of the present embodiment.
In these antenna devices, the radiating element 6 that is a slot-shaped or substantially circular hole is provided on the top surface J of the waveguide branch circuit 100 of the first embodiment. That is, each of the antenna devices 102 and 101 has a waveguide slot array having an array surface (top surface J) in which the radiating elements 6 are arranged at predetermined intervals in the longitudinal direction of the waveguides 1-A and 1-B. An antenna, and the present antenna devices 102 and 1
Reference numeral 01 denotes a total of two rows in the longitudinal direction of the waveguide on the top surface J side of each of the two waveguides 1-A and 1-B of the waveguide branch circuit 100, and a row of radiating elements 6. The two radiating elements 6 are arranged in parallel with each other, and the two rows of the radiating elements 6 are configured to be displaced from each other by about ½ tube wavelength of the electromagnetic wave propagating the electric power.

As described above, the antenna devices 102 and 1
In 01, the arrangement of the radiating elements 6 of the waveguide 1-A and the waveguide 1-B is shifted from each other by approximately 1/2 the in-tube wavelength of the electromagnetic wave from the sub-waveguide 3 to both waveguides. This is because the phases of the distributed electromagnetic waves are opposite to each other (shifted by π [rad]).

FIG. 9 is a graph showing the directivity of the antenna device 101. In this way, the array period S _x of the radiating elements 6 arranged in the x-axis direction in the x-axis direction can be matched with the wavelength in the ½ waveguide tube of the electromagnetic wave propagating the electric power. In 101, no grating lobe is generated in any direction where the angle θ from the z axis is “0 <θ ≦ π / 2” on the xz plane. This is because in the above case, the array period S _{x in the} x-axis direction is
This is because the electromagnetic wave propagating the electric power has a wavelength λ ₀ or less in free space.

For comparison, FIG. 15 is a graph showing the directivity of the conventional waveguide slot array antenna 901. For example, in this way, the antenna 90
1, the two branch circuits 91 are connected to the two waveguides 1-A and 1-B.
0 (Fig. 14) feeds in-phase, so θ = π /
A grating lobe is generated in the 3 (± 60 °) direction.

(Third Embodiment) FIG. 10 shows a perspective view of a waveguide branch circuit 200 in this embodiment. The waveguide branch circuit 200 includes a sub-waveguide for two waveguides 1-A (1-A ') and 1-B (1-B') which are closely arranged and are parallel to each other. The power supplied from the tube 3 is distributed. A reference plane I including the central axes of the two waveguides 1-A and 1-B is parallel to the xy plane, and a top surface J on the waveguide branch circuit parallel to the reference plane I. Therefore, the matching wall 5 extends vertically.

The matching wall 5 has two waveguides 1-
It is provided parallel to the central axes of A and 1-B. On the other hand, the waveguide branch circuit 10 facing the top surface J with the reference plane I interposed therebetween.
The other plane on 0 is called the coupling plane K. On this binding surface K,
A rectangular coupling window 4 whose longitudinal direction is perpendicular to the matching wall 5 is provided, and one opening of the sub-waveguide 3 is perpendicular to the coupling surface K so as to cover the coupling window 4. Are combined.

Further, the coupling window 4 has two waveguides 1-A,
The coupling surface K on 1-B is provided so as to straddle the two waveguides. Also, on the surface where the two waveguides are joined,
A communication port 7 is provided. With the above configuration, the electric power supplied from the sub-waveguide 3 is divided into four branch paths (1-A, 1
-B, 1-A ', 1-B').

FIG. 11 is a sectional view (a) and (b) of the waveguide branch circuit 200. In the waveguide branch circuit 200, the height H of the matching wall 5 with respect to the distance H ₀ between the top surface J and the coupling surface K and the coupling window 4 with respect to the width A ₀ of the wide surface of the sub-waveguide 3 are used. Of the waveguide with good energy efficiency by optimally adjusting the respective values such as the length A in the longitudinal direction of B, or the width B of the coupling window 4 with respect to the width B ₀ of the narrow surface of the sub-waveguide 3. It constitutes a branch circuit. That is, the waveguide branch circuit 100
In the same manner as in the above case, the electric power supplied from the sub-waveguide 3 is adjusted to the four branch paths (1-A, 1) of the two waveguides by optimally adjusting these values H, A and B. -B, 1-A ',
1-B ') can be efficiently and evenly distributed.

Further, the waveguides 1-A (1-A '), 1-B
The phase of the electromagnetic wave evenly distributed to (1-B ′) is equal to the matching wall 5
Since the coupling window 4 and the coupling window 4 are orthogonal to each other as shown in FIG. 11A, they have opposite phases. The matching wall 5 does not necessarily have to be on the boundary surface between the waveguide 1-A (1-A ') and the waveguide 1-B (1-B'). By moving the matching wall 5 in parallel in the y-axis direction of FIG. 10, it becomes possible to configure a waveguide branch circuit of non-uniform distribution.

(Fourth Embodiment) FIG. 12 is a perspective view (a) of an antenna device 300 of this embodiment and a perspective view (b) of an antenna device 202 forming a part of the antenna device 300. In the present antenna device 300, seven antenna devices 202 are arranged in parallel in the y-axis direction so as to be close to each other as shown in the perspective view (a). In the present antenna device 202, the radiating element 6 that is a slot-like hole is provided on the top surface J of the waveguide branch circuit 200 of the third embodiment.

That is, the antenna device 202 includes the radiating element 6
Is a waveguide slot array antenna having an array surface (top surface J) arranged at predetermined intervals in the longitudinal direction of the waveguides 1-A (1-A ') and 1-B (1-B'). Therefore, the present antenna device 202 guides the two waveguides 1-A (1-A ') and 1-B (1-B') of the waveguide branch circuit 200 to the top surface J side. A total of two rows of the radiating elements 6 are arranged in parallel in the longitudinal direction of the wave tube, and the two rows of the radiating elements 6 are further offset from each other by approximately ½ tube wavelength of an electromagnetic wave propagating power. It is composed by.

As described above, in the antenna device 202, the waveguide 1-A (1-A ') and the waveguide 1-B (1-
The arrangement of the radiating elements 6 in B ') is shifted by about 1/2 the guide wavelength of the electromagnetic wave because the phases of the electromagnetic waves distributed from the sub-waveguide 3 to the two waveguides are opposite to each other ( π
This is because it is shifted by [rad].

As described above, the arrangement period S _{x in} the x-axis direction of the radiating elements 6 arranged in the x-axis direction can be matched with the wavelength in the 1/2 waveguide of the electromagnetic wave propagating the electric power. In the antenna device 202 and the antenna device 300, similarly to the antenna device 101, no grating lobe is generated in an arbitrary direction where the angle θ from the z axis is “0 <θ ≦ π / 2” on the xz plane. .

Although not particularly mentioned in each of the above-mentioned embodiments, the inside of the waveguide may be filled with a dielectric material or the like.

The array interval of the radiating elements 6 in one row in the longitudinal direction (x-axis direction) of one waveguide does not necessarily have to match the wavelength in the waveguide. When the beam direction of the supplied electromagnetic wave deviates from the z-axis direction,
The array interval of the radiating elements 6 in one row in the x-axis direction is different from the wavelength in the waveguide.

The waveguide branch circuit of each of the above embodiments can also be used as a waveguide coupling circuit, and thus each antenna device of the above embodiments can also be used as a receiving antenna device.

[Brief description of drawings]

FIG. 1 is a perspective view (a) and (b) of a waveguide branch circuit according to a first embodiment.

FIG. 2 is a sectional view (a) and (b) of a waveguide branch circuit according to the first embodiment.

FIG. 3 is an explanatory diagram showing an operation of the waveguide branch circuit according to the first embodiment.

FIG. 4 is a graph showing reflection characteristics according to the height of a matching wall of the waveguide branch circuit according to the first example.

FIG. 5 is a graph showing the reflection characteristic according to the dimension A of the coupling window of the waveguide branch circuit according to the first example.

FIG. 6 is a graph showing the reflection characteristic according to the dimension B of the coupling window of the waveguide branch circuit according to the first example.

FIG. 7 is a graph showing reflection characteristics according to frequency of the waveguide branch circuit according to the first example.

8A and 8B are perspective views of an antenna device according to a second embodiment.

FIG. 9 is a graph showing the directivity of the antenna device according to the second embodiment.

FIG. 10 is a perspective view of a waveguide branch circuit according to a third embodiment.

FIG. 11 is a sectional view (a) and (b) of a waveguide branch circuit according to a third embodiment.

FIG. 12 is perspective views (a) and (b) of the antenna device according to the fourth embodiment.

FIG. 13 is a perspective view of a conventional waveguide slot array antenna.

FIG. 14 is a perspective view of a waveguide branch circuit according to the related art.

FIG. 15 is a graph showing the directivity of a conventional waveguide slot array antenna.

[Explanation of symbols]

1-A, 1-B ... Waveguide 2 ... Curved waveguide 3 ... Sub-waveguide 4 ... Coupling window 5 ... Matching wall 6 ... Radiating element 7 ... Communication port I ... Reference plane J ... Top surface K ... Coupling surface A ₀ ... width of wide surface of sub-waveguide B ₀ ... width of narrow surface of sub-waveguide H ₀ ... distance A between top-facing surface and coupling surface ... length of coupling window in longitudinal direction B ... Width of coupling window H ... Height of matching wall

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Kunori Nishikawa, Nagachite-cho, Aichi-gun, Aichi 1-41 Yokomichi, Nagakute, Toyota Central Research Institute Co., Ltd. (56) Reference JP-A-59-224901 (JP, A) ) JP-A-58-182301 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01Q 13/10 H01Q 13/22 H01Q 21/08 H01P 3/123 H01P 5/18

Claims (4)

(57) [Claims] 1. A waveguide branch circuit for distributing electric power supplied from a sub-waveguide to two waveguides arranged close to each other and parallel to each other. A matching wall extending perpendicularly to a top surface on the waveguide branch circuit parallel to a reference plane including each central axis of the wave guide and parallel to the central axis; and the top facing surface with the reference surface sandwiched therebetween. A substantially rectangular or substantially elliptical coupling window whose longitudinal direction is perpendicular to the matching wall, the coupling window being provided on the coupling surface on the waveguide branch circuit facing the one side of the sub-waveguide. The section is coupled to the coupling surface perpendicular to the coupling surface so as to cover the coupling window, and the waveguide branch circuit is characterized in that. 2. A curved waveguide having a U-shape or a U-shape that connects the openings on the same side of the two waveguides to each other, and the coupling window has the curved waveguide. The waveguide branch circuit according to claim 1, wherein the waveguide branch circuit is provided on an upper coupling surface, and the power is distributed to two branch paths. 3. The coupling window is provided on a coupling surface on the two waveguides, straddling the two waveguides, and on a surface joining the two waveguides. The waveguide branch circuit according to claim 1, wherein a communication port is provided, and the power is distributed to four branch paths. 4. A transmitter or receiver having radiating elements having array surfaces arranged at a predetermined interval in the longitudinal direction of the waveguide, the radiating elements being constituted by a plurality of waveguides arranged close to each other and parallel to each other. In the waveguide array antenna, the waveguide branch circuit according to any one of claims 1 to 3 is provided with a waveguide longitudinal direction on a side of the two waveguides facing upward. A total of two rows, the rows of radiating elements are arranged in parallel, and the two rows of radiating elements are shifted from each other by approximately 1/2 the guide wavelength of the electromagnetic wave propagating the electric power. An antenna device in which an array structure of the radiating elements is formed using a circuit.