JP2007259047A - Slotted waveguide array antenna apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a slotted waveguide array antenna apparatus capable of suppressing a grating lobe generated at a wider angle in a direction perpendicular to the axis of an waveguide, without changes in broad side dimension and wall thickness of the waveguide. <P>SOLUTION: In the slotted waveguide array antenna, a plurality of rectangular slots 2 elongated to the axial direction of the rectangular waveguide are arranged with spacing of substantially half of a guide wave length on a broad side of rectangular waveguide 1, and each of the slots is arranged in a staggered fashion at a position opposite to an adjacent slot in relation to a centerline of the axis of the rectangular waveguide. A plurality of the slotted waveguide array antennas are provided in a planar shape, and slotted waveguide array antennas adjoining each other in a direction perpendicular to the axis of the rectangular waveguide are grouped to one group. Each of the slotted waveguide array antenna group 3a, 3b, 3c, and 3d adjoining each other in the axial direction is arranged to a zigzag shape mutually in the direction perpendicular to the axis, in an offsetting manner by distance of substantially half of a free space wavelength of an operating frequency. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a waveguide slot array antenna device.

  As a conventional waveguide slot array antenna device having polarization in a direction orthogonal to the tube axis of the waveguide, the slot is extended in the tube axis direction of the waveguide, and the in-tube wavelength is formed on the wide surface of the waveguide. The slots are excited in the same phase by arranging the waveguide slot array antennas in staggered positions opposite to each other with respect to the center line of the waveguide at intervals of 1/2. There are those that emit radio waves (for example, see Non-Patent Document 1).

  A two-dimensional array is formed by arranging a plurality of the waveguide slot array antennas in a plane, and when the interval in the direction perpendicular to the tube axis of the waveguide slot array antenna is D1, the interval D1 is: It is determined by the wide surface dimension of the waveguide and the wall thickness t between adjacent waveguide slot array antennas.

  Further, as a feed structure to the waveguide slot array antenna, a feed waveguide is provided on the back of the waveguide slot array antenna, and the power supplied from the feed port is distributed by the waveguide branch, The waveguide slot array antenna is fed through the coupling slot.

Naohisa Goto, “Waveguide-fed Printed Antenna”, IEICE A, p89-3, 1989

  However, in a conventional waveguide slot array antenna device, when a high frequency band such as a millimeter wave is used, the dimension of the wall thickness cannot be ignored with respect to the wavelength of the used frequency. In manufacturing the antenna, it is difficult to reduce the wall thickness t. As a result, the interval between the waveguide slot array antennas in the direction perpendicular to the tube axis of the waveguide increases, and the tube axis of the waveguide increases. There has been a problem of generating grating lobes in a wide angle direction perpendicular to the direction. In particular, the radiation pattern of the single slot 2 becomes non-directional on the electric field surface, so that the grating lobe level becomes high, which is a serious problem.

  On the other hand, when the wide surface dimension of the waveguide is reduced in order to reduce the interval between the waveguide slot array antennas in the direction orthogonal to the tube axis of the waveguide while maintaining the wall thickness t, the inside of the waveguide of the waveguide Since the wavelength increases, the element spacing of the slot becomes wide. As a result, there may be a problem that a grating lobe is generated in the tube axis direction of the waveguide.

  The present invention has been made to solve the above-described problems associated with the conventional example, and has a wide angle in a direction perpendicular to the tube axis of the waveguide without changing the wide surface dimensions and wall thickness of the waveguide. An object of the present invention is to obtain a waveguide slot array antenna device capable of suppressing a generated grating lobe.

  In the waveguide slot array antenna device according to the present invention, a plurality of rectangular slots extending in the tube axis direction of the rectangular waveguide are provided on the wide surface of the rectangular waveguide at intervals of about 1/2 of the guide wavelength. The waveguide slot array antenna is arranged in a zigzag pattern at positions opposite to each other with respect to the adjacent slot and the center line of the tube axis of the rectangular waveguide. A plurality of the waveguide slot array antennas adjacent to each other in a direction orthogonal to the tube axis of the rectangular waveguide, and the group of the waveguide slot array antennas adjacent in the tube axis direction as a tube axis. It is characterized by being arranged offset in a zigzag manner by a distance of about ½ of the free space wavelength of the used frequency in the orthogonal direction.

  According to the present invention, a plurality of waveguide slot array antennas are provided in a planar shape, and the waveguide slot array antennas adjacent to each other in the direction orthogonal to the tube axis of the rectangular waveguide are grouped and adjacent to each other in the tube axis direction. By arranging a group of waveguide slot array antennas in a direction perpendicular to the tube axis and offset in a zigzag manner by a distance of about half of the free space wavelength of the operating frequency, the wide surface dimensions of the waveguide and the wall Without changing the thickness, it is possible to suppress the grating lobe generated at a wide angle in the direction orthogonal to the tube axis of the waveguide.

Embodiment 1 FIG.
1 is a schematic diagram showing a waveguide slot array antenna apparatus according to Embodiment 1 of the present invention. The waveguide slot array antenna apparatus shown in FIG. 1 includes a plurality of rectangular slots 2 having a length-to-width ratio of about 10: 1 on the wide surface of a rectangular waveguide 1 at intervals of about ½ of the guide wavelength. The slot 2 extends in the direction of the tube axis of the rectangular waveguide 1, and the adjacent slot 2 is positioned opposite to the center line of the tube axis of the rectangular waveguide 1. Are arranged in a staggered pattern. A plurality of such waveguide slot array antennas are provided in a planar shape, and a group of waveguide slot array antennas adjacent in the direction perpendicular to the tube axis are grouped, and a group of waveguide slot array antennas adjacent in the tube axis direction are grouped. They are arranged in a zigzag offset in the direction perpendicular to the tube axis by a distance of about ½ of the free space wavelength of the used frequency.

  That is, in FIG. 1, a plurality of waveguide slot array antennas 3 located at the same position in the tube axis direction (x direction) are defined as waveguide slot array antenna groups 3a, 3b, 3c, and 3d, respectively. When the interval in the direction orthogonal to the tube axis of the antenna (y direction) is D1, the interval D1 is determined by the wide surface dimension of the waveguide and the wall thickness t between adjacent waveguide slot array antennas. The waveguide slot array antenna groups 3a to 3d adjacent to each other in the x direction are arranged offset from each other by a distance D2 in the y direction. Furthermore, the waveguide slot array antenna groups located one position apart are at the same position with respect to the y direction, and as a result, they are arranged in a zigzag shape as a whole.

  FIG. 2 is a schematic diagram showing a feed structure to the waveguide slot array antenna. A feed waveguide 4 is provided on the back surface of the waveguide slot array antenna, and power supplied from the feed port 5 is distributed by the waveguide branch and is passed through the coupling slot 6 to the waveguide slot array antenna. Power is supplied. In FIG. 2, the slalom portions 8 a and 8 b of the feed waveguide 4 are equalized so that the physical lengths (center line of the tube axis) from the feed port 5 to the waveguide branch portion before the coupling slot 6 are equal. Is provided.

  Next, the effects of the present invention will be described. The radiation patterns of the respective waveguide slot array antenna groups 3a to 3d generate grating lobes at a wide angle in a direction perpendicular to the tube axis of the waveguide 1 for the reason described above.

  At this time, if the offset distance D2 is selected and arranged to be about ½ of the wavelength of the operating frequency, the waveguide slot array antenna groups adjacent to each other are in a direction perpendicular to the tube axis of the waveguide 1 (± y The phase of the radio wave radiated in the direction is reversed, and as a result, the grating lobe can be canceled.

As an example of the effect of the present invention, FIG. 3 shows a normalized radiation pattern on the yz plane of FIG. The vertical axis represents the normalized gain, and the horizontal axis represents the angle in the half space of the yz plane. In FIG. 3, the radiation patterns of the array antennas of the present invention and the conventional example shown in FIG. 1 are calculated with the element directivity as cosine electric field directivity (cos ^0.5 θ). According to the present invention, it can be seen that the grating lobe appearing in the wide angle direction can be sufficiently suppressed.

  FIG. 4 shows a conventional two-dimensional normalized radiation pattern, and FIG. 5 shows a two-dimensional normalized pattern of the present invention. In these drawings, the vertical axis represents the angle in the half space of the zx plane, and the horizontal axis represents the angle in the half space of the yz plane. As described above, in the conventional example shown in FIG. 4, grating lobes appear in the wide angle direction of ± y (x = 0 °). On the other hand, in the present invention shown in FIG. 5, no grating lobe appears in the wide angle direction of ± y (x = 0 °). In FIG. 5, a lobe is seen at a position shifted by about 10 ° in the ± x direction from the ± y wide-angle direction, but the level is low because it appears dispersed, and further, it is a problem because it is far from the main surface of the antenna. Don't be.

  As described above, according to the first embodiment, a plurality of waveguide slot array antennas are provided in a planar shape, and the waveguide slot array antennas adjacent in the direction orthogonal to the tube axis of the rectangular waveguide are grouped. Since a group of waveguide slot array antennas adjacent to each other in the tube axis direction are arranged offset in a zigzag manner by a distance of about ½ of the free space wavelength of the used frequency in the direction orthogonal to the tube axis, the waveguide The grating lobe generated at a wide angle in the direction orthogonal to the tube axis of the waveguide can be suppressed without changing the wide surface dimension and the wall thickness of the waveguide.

Embodiment 2. FIG.
FIG. 6 is a schematic diagram showing a waveguide slot array antenna apparatus according to Embodiment 2 of the present invention. In FIG. 6, the same parts as those in the first embodiment shown in FIG. In the second embodiment shown in FIG. 6, the slot is composed of an obliquely inclined slot 9 arranged obliquely by the same angle in the same direction from the tube axis of the rectangular waveguide 1.

  The direction of the slot is not limited to the tube axis direction of the waveguide 1 as shown in the first embodiment. As in the obliquely inclined slot 9 shown in FIG. 6, the direction of the slot may be inclined obliquely from the tube axis of the waveguide 1. Thereby, the polarization direction of the antenna can be changed.

  Further, at this time, the power radiated from the slot 9 alone to the ± y direction side is reduced. Since the radiation pattern of the array antenna such as a grating lobe is determined by the product of the element single directivity and the array arrangement coefficient, an effect that the grating lobe level also decreases can be obtained as the element single directivity decreases.

  As described above, according to the second embodiment, a waveguide slot array antenna device that realizes an arbitrary polarization direction and further suppresses a grating lobe appearing in a wide angle direction can be obtained.

1 is a schematic diagram showing a waveguide slot array antenna device according to Embodiment 1 of the present invention. It is a schematic diagram which shows the electric power feeding structure to the waveguide slot array antenna shown in FIG. FIG. 2 is a diagram showing a normalized radiation pattern on the yz plane of FIG. 1 as an example of the effect of the present invention. It is a figure which shows the two-dimensional normalization radiation pattern of a prior art example for comparing and showing the effect of this invention. It is a figure which shows the two-dimensional normalization pattern of this invention. It is a schematic diagram which shows the waveguide slot array antenna apparatus which concerns on Embodiment 2 of this invention.

Explanation of symbols

  1 rectangular waveguide, 2 rectangular slot, 3 waveguide slot array antenna, 3a, 3b, 3c, 3d waveguide slot array antenna group, 4 feed waveguide, 5 feed port, 6 coupling slot, 8a, 8b Slalom part of the feeding waveguide 4, 9 slanting slot.

Claims (2)

A plurality of rectangular slots extending in the tube axis direction of the rectangular waveguide are arranged on the wide surface of the rectangular waveguide at intervals of about ½ of the guide wavelength, and adjacent slots and the rectangular waveguide are arranged. In the waveguide slot array antenna arranged in a staggered manner at positions opposite to each other with respect to the center line of the tube axis of the tube,
A plurality of the waveguide slot array antennas are provided in a planar shape, and the waveguide slot array antennas adjacent to each other in a direction orthogonal to the tube axis of the rectangular waveguide are grouped, and the waveguides adjacent to each other in the tube axis direction. 1. A waveguide slot array antenna device characterized in that a group of tube slot array antennas are arranged offset in a zigzag manner by a distance of about ½ of the free space wavelength of the used frequency in a direction orthogonal to the tube axis. The waveguide slot array antenna device according to claim 1,
The slot is inclined at the same angle in the same direction with respect to the tube axis of the rectangular waveguide. The waveguide slot array antenna device.

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