JP4662037B2 - Center-fed waveguide slot array antenna - Google Patents

Description

  The present invention belongs to a technical field relating to a feeding structure of a waveguide slot array antenna used particularly in a microwave band and a millimeter wave band.

A conventional slot array antenna has a structure in which a base plate provided with a groove for a radiating waveguide and a groove for a feeding waveguide is covered with a slot plate having a slot corresponding to the radiating waveguide.
In the centrally fed waveguide slot array antenna, the centrally fed waveguide has a structure in which the narrow wall surface (E surface) coincides with the direction of the antenna opening surface.
The reason is that a slot cannot be provided in a portion corresponding to the position of the feed waveguide of the slot plate. If the wide wall surface (H plane) of the feed waveguide is aligned with the direction of the antenna opening surface, the slot This is because there is a problem that the width of the portion in which the line cannot be provided becomes large and the side lobe level in the directivity increases.

Then, power feeding is performed by providing a power feeding hole on the back side (E surface) of the antenna at the central portion of the power feeding waveguide (see, for example, Patent Document 1 and Patent Document 2).
Japanese Patent Application No. 2004-212909 ([0008], [0010], FIGS. 1 and 4) Japanese Patent Application No. 2005-042053 (FIGS. 3 and 5)

By the way, when power is supplied from the E plane at the central portion of the feeding waveguide, the phase of the electromagnetic wave fed from the central portion to both sides is in-phase power feeding. Therefore, adjacent radiation waveguides that are fed by the first E-plane direction cross-branch on both sides of the feed hole are fed in phase.
The width (that is, the depth) of the wide wall of the feed waveguide is adjusted so that power is fed in opposite phase to the radiation waveguide other than the above, and radiation is performed at each position where the wavelength in the tube is ½ in the feed waveguide. Since the waveguides are arranged, adjacent radiation waveguides are fed with opposite phases.
That is, the radiation waveguides adjacent to each other across the line perpendicular to the longitudinal direction of the feeding waveguide through the feeding hole are in-phase feeding. When radiation waveguides are provided on both H planes of the feed waveguide, two sets, one set on one H plane side and one set on the other H plane side, are in-phase power feed. In the case of common-phase power supply, current must flow between the boundary wall and the slot plate that partition adjacent radiation waveguides, so the upper surface of the boundary wall and the slot plate are in close contact with each other so that good conduction can be obtained. I have to let you.

  For this reason, in order to establish electrical continuity between the slot plate and the boundary wall between the base body radiation waveguide, a copper foil of a copper foil printed thin dielectric sheet provided with a slot as a slot plate is attached to the base body with a conductive adhesive sheet. In the case of a metal plate slot, the slot plate is screwed or fastened to the base body at a critical portion (Japanese Patent Application No. 2002-123376). Adhesion with an adhesive or an adhesive sheet is performed on a flat surface other than the groove, and conductive bumps provided in advance at the corresponding locations of the slot plate are brought into contact with the base body through the adhesive layer or the adhesive sheet (Japanese Patent Application 2002). -1668050) have been made.

  However, as a matter of course, these contrivances increase the number of parts and processes therefor, increase the cost, and there is a problem of deterioration over time in adhesives, pressure-sensitive adhesives, conductive pressure-sensitive adhesive sheets and the like.

  In view of the above-mentioned problems of the prior art, the problem of the present invention is that the boundary wall and the slot plate that divide adjacent radiation waveguides do not completely adhere to each other until screws or adhesives are used. Another object of the present invention is to provide a waveguide slot array antenna having a good feeding structure.

In order to solve the above-described problems, the center-fed waveguide slot array antenna of the present invention has the following configuration.
That is, on the inside of the narrow wall surface on the back side of the antenna of the feeding waveguide that feeds the radiation waveguides extending in parallel from the wide wall surface (H surface) of the feeding waveguide by the E-plane direction cross branch, A reflection suppression wall is provided in correspondence with the coupling position of the power supply waveguide , and the tube axis direction extends perpendicularly to the antenna radiation surface toward the antenna rear surface on the wide wall surface (H surface) in the longitudinal center portion of the feed waveguide. A central feed waveguide slot array antenna having a feed structure in which narrow walls of a rectangular waveguide are coupled .

  The center feed waveguide slot array antenna of the present invention does not feed power by providing a feed hole in the bottom surface, that is, the narrow wall surface (E surface) of the feed waveguide as in the prior art, but from the central portion in the longitudinal direction of the feed waveguide. The feeding path from the rear of the antenna is coupled to the wide wall surface (H plane) of the feeding waveguide at a position deviating in the radial waveguide tube axis direction. That is, power is supplied from the H plane to the central feeding waveguide.

For this reason, power feeding from the power feeding point to both sides is reversed phase power feeding.
Thereby, the adjacent radiation waveguides fed by the first E-plane direction cruciform branch on both sides of the feeding point are also fed with opposite phases, and the other neighboring radiation waveguides are fed with opposite phases as described above. All adjacent radiating waveguides are in antiphase feeding.
In the case of reversed-phase power feeding, the current flowing between the boundary wall that divides the adjacent radiating waveguides and the slot plate is exactly opposite to each other, canceling each other out to zero, and as a result In addition, since no current flows between the boundary wall and the slot plate, there is no electrical problem even if the boundary wall upper surface and the slot plate are not in close contact with each other and a gap is formed to be in an insulating state.

  For this reason, as in the prior art, screws or tacks are used to ensure conduction between the two, a conductive adhesive is used, or a conductive bump is provided on the slot plate to allow the adhesive to penetrate. There is no need to make contact with the upper surface of the wall, and there is an advantage that there are no problems such as an increase in parts and processes, an associated high cost, and aged deterioration of adhesives and pressure-sensitive adhesives.

The waveguide slot array antenna includes a plate-shaped metal base body provided with grooves for a radiation waveguide and a power supply waveguide, and a slot plate that covers the base body.
In order to provide the feeding structure in the antenna of the present invention, the width of the boundary wall between the radiating waveguides arranged on both sides of the longitudinal central portion of the feeding waveguide of the base body is larger than the width of the boundary wall of the other part. Therefore, a square groove having a predetermined dimension is cut in the longitudinal direction of the boundary wall from the wide wall (H surface) portion of either one of the feeding waveguides of this portion, and the width is narrower than the boundary wall width, and from the bottom of the square groove. By providing an opening penetrating to the back side (back side) of the base body, power can be fed from the back side of the base body to the wide wall surface (H surface) of the feed waveguide, and this structure is the simplest, counterbore method And the die casting method is easy to manufacture and is the best embodiment.

Embodiments of the antenna of the present invention will be described below with reference to the drawings.
FIG. 1 is a plan view of an antenna opening surface side of a base body 1 of the antenna of the present invention.
The basic structure is that a feed waveguide 4 of a horizontal straight line is provided in a groove shape on one surface of a thick plate-like metal body at a position in the middle in the vertical direction. In the direction, the radiation waveguide 2 is provided in a groove shape. In the drawing, 16 grooves on the upper and lower sides of the radiation waveguide 2 are provided.
A boundary wall 3 is formed between adjacent radiation waveguides 2. Just the middle boundary wall 7 is wider than the boundary wall 3, and a power feed hole 6 is provided in this portion.

The feed hole 6 passes through the base body 1 in the direction perpendicular to the paper surface, and the upper side in FIG. 1 is open-coupled to the H surface of the feed waveguide 4. Thereby, the electromagnetic wave fed from the back side of the base body 1 is fed from the side wall surface of the feeding waveguide 4, that is, the H plane.
Reference numeral 5 denotes a reflection suppression wall provided at the bottom of the feed waveguide 4 so as to correspond to each radiation waveguide 2.

FIG. 2 is a plan view of the slot plate 8 that covers the base body 1 of FIG.
A slot 9 is cut in the slot plate 8 at a position corresponding to each radiation waveguide 2 when the base plate 1 is covered.

FIG. 3 is a view showing the positional relationship of the slots 9 when the base plate 1 is covered with the slot plate 8.
By covering the slot plate 8, the portion of the radiation waveguide 2 becomes a radiation waveguide, and the portion of the feed waveguide 4 becomes a feed waveguide.

FIG. 4 is a three-dimensional perspective view showing the feed structure of the antenna of the present invention as a radiation waveguide 10, a feed waveguide 11, and a feed waveguide structure 12 to the feed waveguide 11.
A coaxial waveguide converter 13 or a standard waveguide is coupled to the lower opening surface of the feed waveguide structure 12.
Feeding is performed from the coaxial waveguide converter 13 or the standard waveguide, and through the feeding waveguide structure 12, is fed in reverse phase from the H surface of the feeding waveguide 11 in both the left and right directions in the feeding waveguide 11. Power is supplied to a plurality of radiation waveguides 10 that are coupled to the waveguide 11 in a cross shape from the E surface to the H surface, and is radiated from a slot (not shown) to space.

  1 and 4, the radiation waveguide 2 with the base plate 1 covered with the slot plate 8 corresponds to the radiation waveguide 10 of FIG. 4. Similarly, the feed waveguide 4 Corresponds to the feeding waveguide 11, and the feeding hole 6 corresponds to the feeding waveguide structure 12.

Hereinafter, various characteristics of the power feeding structure configured as shown in FIG. 4 will be described.
First, the matching of the feeding waveguide structure 12 is performed by changing the dimensions a ₁ , a ₂ , and b, and at a design frequency of 25.3 GHz, a ₁ = 10.668 mm, a ₂ = 9.2 mm, b = 3. It was 4 mm.
Further, the dimensions of the feeding waveguide 11 are E plane width = 3.6 mm, H plane width = 7.2 mm, and the dimensions of the radiation waveguide 10 are narrow wall width = 3 mm and wide wall width = 8 mm. The interval was 6 mm.

FIG. 5 is a graph showing reflection and distribution characteristics when power is supplied from Port 1 in FIG.
The solid line indicates the frequency characteristic of reflection at Port 1, the dotted line indicates the frequency characteristic of distribution from Port 1 to Ports 4, 5, 6, and 7, and the broken line indicates the frequency characteristic of distribution from Port 1 to Port 2, 3 and Ports. .
The reflection characteristic is a good characteristic of −20 dB or less in the design frequency band 25.3 GHz ± 200 MHz, and the distribution characteristic is also flat and good.

FIG. 6 is a distribution phase characteristic diagram.
The solid line is the phase of distribution to Port 2, and the broken line is the phase of distribution to Port 3. It is shown that the phase difference between the two is a 180 ° difference over the entire frequency range of FIG.
These analyzes used a simulator by the finite element method.

FIG. 7 is a diagram showing the reflection characteristics of the entire antenna configured as shown in FIG.
In the design frequency band 25.1 GHz to 25.5 GHz, a favorable result of −20 dB or less is obtained.

FIG. 8 is an H-plane radiation directivity diagram at the design frequency (25.3 GHz) of the antenna configured as shown in FIG.
The first side lobe is good at -14 dB or less.

FIG. 9 is also an E-plane radiation directivity diagram.
The first side lobe is -12 dB and higher than that of the H plane, which is considered to be due to the large width of the boundary wall 7 in FIG.

It is a top view by the side of the antenna opening surface of the base body of this invention antenna. FIG. 2 is a plan view of a slot plate that covers the base body of FIG. 1. It is a figure which shows the positional relationship of a slot when the slot board of FIG. 2 is covered on the base body of FIG. It is the three-dimensional perspective view which showed the feed structure of this invention antenna with the radiation waveguide, the feed waveguide, and the feed waveguide structure to this feed waveguide. 5 is a graph showing reflection and distribution characteristics when power is supplied from Port 1 in FIG. 4. FIG. 5 is a distribution phase characteristic diagram when power is supplied from Port 1 in FIG. 4. It is a figure which shows the reflection characteristic of the whole antenna comprised as FIG. FIG. 4 is an H-plane radiation directivity diagram at the design frequency of the antenna configured as shown in FIG. 3. FIG. 4 is an E-plane radiation directivity diagram at the design frequency of the antenna configured as shown in FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base body 2 Radiation waveguide 3 Boundary wall 4 Feeding waveguide 5 Reflection suppression wall 6 Feeding hole 7 Boundary wall 8 Slot plate 9 Slot 10 Radiation waveguide 11 Feeding waveguide 12 Feeding waveguide structure 13 Coaxial waveguide conversion vessel

Claims (1)

The coupling of the radiation waveguide is performed on the inside of the narrow wall on the back side of the antenna of the feeding waveguide that feeds the radiation waveguide extending in parallel from the wide wall surface (H surface) of the feeding waveguide by the E-plane direction cross branch. A rectangular waveguide that is provided with a reflection suppression wall corresponding to the position and that extends to the back side of the antenna with the tube axis direction perpendicular to the antenna radiation surface on the wide wall surface (H surface) at the center in the longitudinal direction of the feed waveguide. A central feed waveguide slot array antenna having a feed structure in which narrow walls of wave tubes are coupled .

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