JP2007053514A - Waveguide slot antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waveguide slot antenna wherein the presence of a feeding waveguide causes no left right weight unbalance and even the insertion of a spurious radiation suppressing filter causes no increase in the height between a radiation waveguide and a pedestal. <P>SOLUTION: A feeding port 9 is provided to a middle part in a guide axial direction of a lower wide wall face of the radiation waveguide 1, whose cross-sectional shape is rectangular, provided with radiation slots 2 at narrow wall faces of the radiation waveguide 1, which is placed so that its wide wall faces take horizontal directions, a feeding port structure coupled to the feeding port 9 and the other transmission direction of an electromagnetic wave of which is directed in the same direction as the direction of the narrow wall faces provided with the radiation slots 2 is provided, and the feeding waveguide 6 is connected to an opening 8 whose direction is the same as the direction of the narrow wall faces. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention belongs to the technical field of a waveguide slot antenna in which a plurality of radiation slots are provided at predetermined intervals in the tube axis direction on a narrow wall surface (E surface) of a rectangular cross-section waveguide.

As a main application field of the waveguide slot antenna, there is a marine radar antenna.
FIG. 3 is a front view of the radiation waveguide 1 of the slot antenna in which the radiation slot 2 is provided on the E surface of the radiation waveguide 1 having a rectangular cross section.
In the radiating slot 2, inclined slots that can obtain a predetermined current distribution obtained from the relationship between the efficiency and the horizontal beam designed to be inclined with respect to the vertical line are alternately arranged at intervals of almost a half of the guide wavelength. ing.
Since the radar antenna is radiated from the radiation slot 2 or received by the radiation slot 2, the radio wave is usually rotated over the entire horizontal direction.

Such power supply to the radiation waveguide 1 is currently performed from the end of the radiation waveguide 1 by the power supply waveguide (Non-Patent Document 1).
FIG. 4 is a diagram showing a power feeding structure to the radiation waveguide 1, and FIG. 4A is a diagram showing power feeding to the end portion.
The feed waveguide 10 rising along the rotation center axis is bent so as to be parallel to the radiation waveguide 1 when reaching the bottom of the radiation waveguide 1 (in the figure, the end of the radiation waveguide 1). To the right end) where it is connected to the radiating waveguide 1.

(B) is a structure in which the feeding waveguide 11 is vertically connected to the central portion of the radiation waveguide 1 although not practically used (Patent Documents 1 and 2).
At present, a method of inserting a filter is used to suppress radiation of unnecessary frequencies, but this filter is inserted in the middle of the feed waveguide.
Yoshimura Yoshihiro, Fujimori Yasuyuki, Basics of Revised Radar Engineering, First Edition, Keigaku Publishing Co., Ltd., August 10, 1975, p. 145-146 Japanese Examined Patent Publication No. 63-53726 (Fig. 1) Japanese Examined Patent Publication No.59-27528 (FIGS. 1 and 2)

  However, in the power feeding structure as shown in FIG. 4A, since there is a power feeding waveguide 10 from the center to the right end, the structure becomes asymmetrical and the rotational balance is deteriorated. Further, there is a problem that the weight is increased due to the feed waveguide 10 and the load on the rotary drive device becomes heavy.

The feed structure in FIG. 4B does not have the problem of left-right asymmetry as in FIG. 4A, but if a filter for suppressing unwanted radiation is inserted, the feed waveguide 11 becomes longer and a pedestal (not shown) ) To the radiation waveguide 1 is increased, and the rotational drive shaft is lengthened to cause a problem in the rotational balance, and the wind resistance is deteriorated because the entire apparatus is enlarged. In addition, it becomes heavier and more susceptible to vibrations.
In the case of (a), since the filter is inserted into the horizontal portion of the feed waveguide 10, there is no problem that it becomes high.

  An object of the present invention is to solve the above-mentioned problems in the structure for feeding a rotating waveguide slot antenna.

In order to solve the above problems, the waveguide slot antenna of the present invention has the following configuration.
In other words, a narrow wall (E surface) on one side of a rectangular waveguide has a plurality of radiation slots at predetermined intervals in the tube axis direction, and is coupled to one wide wall surface (H surface) at the center in the tube axis direction. A waveguide slot antenna having a feed opening structure having a transmission direction in a direction in which a narrow wall surface having a slot is directed.

As described above, in the waveguide slot antenna of the present invention, the feeding structure is coupled to the H plane at the center of the radiation waveguide having the radiation slot on the E plane, and the direction in which the E plane having the radiation slot is oriented. If the tube axis of the radiating waveguide is horizontal, the feed port structure is on the lower side, and the normal of the E plane having the radiation slot is oriented horizontally, the feed port The transmission direction of the structure also faces the front of the antenna.
When a waveguide slot antenna is used as a marine radar antenna, a reflector that is tilted vertically from the radiating waveguide and extends forward to form a vertical beam is attached. As can be taken, the axis of rotation is in a position ahead of the radiating waveguide. It is desirable that the feeding waveguide be as close to the center of rotation as possible so that the rotation balance can be achieved.

In such a case, the antenna of the present invention has an advantage that the feeding waveguide can be extended horizontally from the lower surface of the radiation waveguide to near the center of rotation.
In addition, since a filter for suppressing unwanted radiation can be inserted into the horizontal portion, there is an advantage that the height between the radiation waveguide and the pedestal does not increase in order to insert the filter.

  In addition, the reflection from the wall surface of the power supply port structure is canceled by the reflection from the connection portion with the power supply waveguide coupled to the power supply port structure, and there is an advantage that the reflection can be reduced overall.

  In the antenna feeding port structure according to the present invention, when the H surface of the radiation waveguide is placed horizontally, the E surface where the radiation slot is cut by coupling to the lower H surface is oriented. However, the opening surface extends slightly forward from the E surface where the radiation slot is provided, and the upper side of the opening surface is from the H surface to which the power feeding port structure is coupled. Setting it to a slightly lower position makes it easier to connect another waveguide for power feeding to this opening surface, and further, it is a dimension that cancels reflection from the wall surface of the power feeding opening structure by reflection at this connecting portion This can be said to be the best mode in that setting is easy.

Hereinafter, embodiments of the waveguide slot antenna of the present invention will be described with reference to the drawings.
FIG. 1 is a structural perspective view of an embodiment of a waveguide slot antenna of the present invention.
FIG. 2 is a cross-sectional view of the radiation waveguide 1 of FIG. 1 viewed in the tube axis direction. A plurality of radiation slots 2 are cut in the narrow wall surface (E surface) of the radiation waveguide 1.
When viewed from the front of the antenna, the radiating slot 2 is provided with slots that are alternately inclined to the left and to the right, and looks like an array of C-shaped or V-shaped cuts. The interval is a dimension around one half of the guide wavelength at the operating frequency.
The feed port structure 3 is coupled to the lower wide wall surface (H surface) of the central portion of the radiation waveguide 1 in the tube axis direction. The opening surface 8 faces in the same direction as the E surface on which the radiation slot 2 is provided, that is, in front of the antenna, and is provided so as to protrude forward from the E surface.

  And this protrusion part becomes the filter insertion part 5 which can insert a filter. Then, the feed waveguide 6, which is indicated by a two-dot chain line and whose vertical and horizontal dimensions are larger than that of the aperture plane 8, is connected to the aperture plane 8.

The radiation waveguide 1 is attached with a reflecting plate 4 composed of a metal plate extending upwardly from the upper and lower H surfaces and a metal plate extending downwardly.
By attaching the reflecting plate, the center of gravity in the front-rear direction of the antenna moves to the front of the radiation waveguide 1. Therefore, it is desirable that the center of rotation for smoothly rotating the antenna is the center of gravity. In that case, the feed waveguide 6 must also be drawn to near the rotation center axis.

  Therefore, there exists an advantage that the opening surface 8 of the electric power feeding opening structure 3 has faced the antenna front. In the case of FIG. 2, the case where the feeding waveguide 6 connected to the feeding port structure 3 extends downward and has a good positional relationship is shown.

The electromagnetic wave fed from the feed waveguide 6 is branched and fed from the feed port 9 on the lower H surface of the radiation waveguide 1 to the left and right. In this case, since it is H-plane feeding, the left and right sides are fed with opposite phases.
Therefore, the phase is opposite between the radiation slots 2 on both sides of the power supply port 9.
The distance between the adjacent radiation slots 2 and the adjacent radiation slots 2 is approximately one half of the guide wavelength. Therefore, the adjacent radiation slots 2 are also opposite in phase, so that predetermined radiation characteristics can be obtained. It has become.
Next, the reflection from the wall surface in the power supply port structure 3 is reduced by the reflection by the reflection at the connection portion between the power supply port structure 3 and the power supply waveguide 6, thereby reducing the reflection comprehensively.

As shown in FIG. 1, the vertical and horizontal dimensions of the feeding waveguide 6 at the connection portion are larger than the vertical and horizontal dimensions of the opening surface 8 of the feeding port structure 3. Therefore, the part beyond the opening surface 8 becomes a wall, and reflection occurs here.
The reflection seen from the input side of the feeding waveguide 6 is adjusted by adjusting the dimension b in FIG. 1 and the dimensions a1 and a2 in FIG. 2 so that the reflection and the reflection from the wall surface of the feeding port structure 3 cancel each other. Set the dimensions so as to reduce the number.
When the waveguide slot antenna is actually used as a marine radar antenna, it is housed in the radome 7 and used.

It is a structure perspective view of the Example of this invention waveguide slot antenna. It is sectional drawing seen in the tube-axis direction of the radiation waveguide of FIG. It is a front view of the slot antenna radiation waveguide which provided the radiation slot in the E surface of the radiation waveguide of rectangular cross section. It is a figure which shows the conventional electric power feeding structure to a slot antenna radiation | emission waveguide.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radiation waveguide 2 Radiation slot 3 Feed port structure 4 Reflector 5 Filter insertion part 6 Feed waveguide 7 Radome 8 Opening surface 9 Feed port 10 Feed waveguide 11 Feed waveguide 12 Rotation center axis

Claims (1)

The narrow wall surface on one side of the rectangular waveguide has a plurality of radiating slots at predetermined intervals in the tube axis direction, and the narrow wall surface having the slot is connected to the wide wall surface on the one side in the center of the tube axis direction. A waveguide slot antenna having a feed opening structure having a transmission direction in a direction.

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