radar antenna

Abstract

To provide a radar antenna that has the required characteristics and performance while keeping manufacturing costs low.SOLUTION: A radar antenna includes a plurality of radiation stubs 21 that are formed on the front side of a plate-like horizontally elongated housing 2, and are groove-shaped extending approximately perpendicular to the longitudinal direction of the housing 2, and are arranged in parallel along the longitudinal direction of the housing 2, a waveguide portion that is formed within the housing 2, extends along the longitudinal direction of the housing 2, and communicates with each radiation stub 21, and a first dielectric 3 that is provided within each radiation stub 21, and is formed such that the center is thin and both ends are thick in the longitudinal direction of the radiation stub 21.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This invention relates to a radar antenna used on land, ships, etc.

Background Art

[0002] As a radar antenna used on land, ships, etc., a plurality of slots (slots) are formed on the front surface of a waveguide, and by adjusting the tilt angle, width, cut depth, arrangement, etc. of each slot, a radar antenna provided with a radiating waveguide having predetermined directivity characteristics or frequency characteristics is known (for example, see Patent Document 1, etc.).

[0003] In such a radar antenna, as the vertical plane directivity, null fill (the gain does not become null in all directions) is required to reduce the blind zone of the target, and in order to achieve it with a limited antenna height, it was necessary to select a horn type. That is, a horn-shaped flare composed of an upper flare and a lower flare was arranged so as to sandwich a waveguide in which a plurality of slots were formed, and the waveguide and the flare were assembled by a plurality of waveguide holding brackets.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, the conventional radar antenna requires a flare, which has led to an increase in cost. Also, as shown in FIG. 7, in order to assemble the upper flare 102 and the lower flare 103 to the waveguide 101, there is a possibility that a gap G occurs, for example, between the waveguide 101 and the upper flare 102 due to an assembly error, resulting in deterioration of the side lobe characteristics.

[0006] It should be noted that the "?" in the translation of item 29 is because the original text seems to be incomplete or there may be some inaccuracies in the reference number. It is recommended to double-check the original Japanese text for a more accurate translation.Furthermore, conventional radar antennas require a plate-shaped suppressor 104 to connect the upper flare 102 and the lower flare 103 as a countermeasure against cross-polarization. This increases the number of parts and assembly steps, leading to higher costs.

[0007] Against this backdrop, there was a need for a new radar antenna structure that not only provided the necessary characteristics and performance but also reduced manufacturing costs.

[0008] Therefore, the present invention aims to provide a radar antenna that can obtain the necessary characteristics and performance while keeping manufacturing costs low. [Means for solving the problem]

[0009] To achieve the above objective, the invention described in claim 1 is a radar antenna characterized by comprising: a plurality of radiating stubs formed on the front side of a plate-shaped, horizontally elongated housing, groove-shaped and extending substantially perpendicular to the longitudinal direction of the housing, and arranged parallel to the longitudinal direction of the housing; a waveguide portion formed inside the housing, extending along the longitudinal direction of the housing and communicating with each of the radiating stubs; and a first dielectric provided inside each of the radiating stubs, having a thin center and thick ends in the longitudinal direction of the radiating stub.

[0010] The invention described in claim 2 is characterized in that, in the radar antenna described in claim 1, a second dielectric material having a dielectric constant smaller than that of the first dielectric material is provided in the waveguide portion. [Effects of the Invention]

[0011] According to the invention described in claim 1, the first dielectric material provided in each radiating stub is formed with a thin center and thick ends in the longitudinal direction of the radiating stub, thereby controlling the phase of the radio waves radiated from the radiating stub and enabling control of the vertical plane directivity (vertical plane beam width). As a result, there is no need to arrange a horn-shaped flare as in the conventional method, which reduces manufacturing costs and prevents deterioration of side lobe characteristics due to assembly errors of the flare.

[0012] Furthermore, because multiple radiating stubs are arranged in parallel, cross-polarization does not occur, eliminating the need for conventional suppressors. This reduces the number of parts and assembly time, thereby lowering manufacturing costs.

[0013] In this way, it becomes possible to keep manufacturing costs low while ensuring the necessary characteristics and performance (such as vertical plane directivity and cross-polarization suppression).

[0014] According to the invention described in claim 2, since a second dielectric material having a lower dielectric constant than the first dielectric material is provided in the waveguide section, the propagation wavelength of radio waves in the waveguide section becomes shorter, making it possible to miniaturize the antenna. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic perspective view showing a radar antenna according to an embodiment of the present invention. [Figure 2] Figure 1 is a plan view of the radar antenna. [Figure 3] Figure 2 is a cross-sectional view of BB. [Figure 4] This is a cross-sectional view showing the first and second dielectrics in the AA section of Figure 2. [Figure 5] This is a conceptual diagram showing the propagation state of radio waves through the first dielectric material placed on each radiating stub of the radar antenna in Figure 1. [Figure 6] This figure shows the vertical plane directivity characteristics of the radar antenna shown in Figure 1 and a conventional radar antenna. [Figure 7] It is a side view showing a conventional radar antenna.

Embodiments for Carrying out the Invention

[0016] Hereinafter, this invention will be described based on the illustrated embodiments.

[0017] FIG. 1 is a schematic perspective view showing a radar antenna 1 according to an embodiment of this invention, and FIG. 2 is a plan view of this radar antenna 1. This radar antenna 1 is a radar antenna used on land, ships, etc., and is entirely in a substantially flat plate shape that is horizontally long.

[0018] The housing 2 is made of metal and is in a substantially rectangular (horizontally long) flat plate shape that is slender, and a plurality of radiation stubs 21 are formed on the front side (radiation side) thereof. These radiation stubs 21 are in a groove shape that extends substantially perpendicular to the longitudinal direction of the housing 2 (in the short side direction of the housing 2), and a plurality of them are arranged in parallel along the longitudinal direction of the housing 2. Further, the width, length, groove depth, arrangement interval, etc. of the radiation stubs 21 are set so that predetermined antenna characteristics (directivity characteristics, frequency characteristics, etc.) can be obtained in a state where a first dielectric body 3 and the like, which will be described later, are disposed therein. Here, in FIG. 1, only the radiation stubs 21 are shown, excluding the portions between the radiation stubs 21 of the housing 2. Also, the length in the short side direction of the housing 2 (the height of the radar antenna 1) h1 is set to be approximately the same as the height h2 of the conventional radar antenna shown in FIG. 7.

[0019] Furthermore, as shown in FIG. 3, a waveguide portion 22 that extends along the longitudinal direction of the housing 2 and communicates with each radiation stub 21 is formed inside the housing 2. That is, the waveguide portion 22 is tubular and is formed to extend over substantially the entire length in the longitudinal direction of the housing 2, and communicates with each radiation stub 21 (is spatially connected). Thereby, the power from the power supply port 23 provided at the central portion on the back side of the housing 2 is supplied to each radiation stub 21 via the waveguide portion 22.

[0020] In addition, the depth of the waveguide portion 22 (height in the thickness direction of the housing 2) is formed so as to gradually decrease from the central portion of the housing 2 toward both end sides, whereby the power from the power supply port 23 is evenly supplied to each radiation stub 21. Further, a concave portion 22a recessed toward the back side of the housing 2 is formed in the central portion of the waveguide portion 22 (the portion facing the power supply port 23), and impedance matching is achieved by this concave portion 22a.

[0021] Such a housing 2 may be integrally formed or may be composed of a plurality of divided parts. For example, it may be composed of a front-side part and a back-side part with the waveguide portion 22 as a boundary.

[0022] On the other hand, a first dielectric body 3 is disposed in each radiation stub 21, and this first dielectric body 3 is formed such that the central portion is thin and both end portions are thick in the longitudinal direction of the radiation stub 21. That is, as shown in FIG. 4, the first dielectric body 3 of this embodiment is formed such that the front side of the housing 2 is flat and flush with the front surface of the housing 2, the thickness of the central portion is substantially zero, and it thickens linearly toward both end portions. Here, since FIG. 3 is a cross-sectional view at the central portion in the width direction (direction perpendicular to the longitudinal direction) of the housing 2, the first dielectric body 3 is not shown.

[0023] Thus, by forming the central portion of the first dielectric body 3 thin and both end portions thick, the phases of the radio waves radiated from the central side and both end sides of the radiation stub 21 are controlled, and the vertical plane directivity (vertical plane beam width) is controlled. That is, as shown in FIG. 5, the power supply port 23 side of the housing 2 (the second dielectric body 4 side described later) becomes an equiphase surface having the same phase over the entire length of the radiation stub 21. On the other hand, on the front side of the housing 2, that is, the radiation side, the phase is delayed and the propagation speed becomes slow at both end sides of the radiation stub 21 where the first dielectric body 3 is thick, so the phase and propagation speed shift (delay) in a tapered manner from the central side toward both end sides. As a result, the vertical plane directivity is controlled.

[0024] The thickness of the first dielectric 3 is set so that the desired vertical plane directivity (vertical plane beam width) is obtained. In this embodiment, the thickness in the center of the radiating stub 21 is almost zero, and the thickness t at both ends is set to 1 / 4 of the wavelength inside the tube.

[0025] Furthermore, as shown in Figures 3 and 4, a second dielectric 4 having a dielectric constant smaller than that of the first dielectric 3 is disposed in a portion of the radiating stub 21 and within the waveguide section 22. That is, as described above, the first dielectric 3 is disposed with a predetermined thickness on the front side (opposite the waveguide section 22 side) of the radiating stub 21, and the second dielectric 4 is disposed across the radiating stub 21 and the waveguide section 22 on the lower side (waveguide section 22 side).

[0026] Here, the specific materials of the first dielectric 3 and the second dielectric 4 can be anything, but for example, the first dielectric 3 can be a low-loss Teflon-based dielectric with a low dielectric constant, and the second dielectric 4 can be a low-loss foam material with a low dielectric constant. In this embodiment, the second dielectric 4 is provided in order to shorten the propagation wavelength of radio waves and to miniaturize the radar antenna 1, but the second dielectric 4 may be omitted, leaving only space or air.

[0027] With this configuration of radar antenna 1, the first dielectric 3 provided within each radiating stub 21 is formed with a thin center and thick ends in the longitudinal direction of the radiating stub 21. This allows the phase of the radio waves radiated from the radiating stub 21 to be controlled, making it possible to control the vertical plane directivity (vertical plane beam width). Therefore, there is no need to arrange a horn-shaped flare as in the conventional design, which makes it possible to keep manufacturing costs low and prevents deterioration of side lobe characteristics due to assembly errors of the flare. For example, as shown in Figure 6, compared to a conventional radar antenna, this radar antenna 1 has suppressed side lobes and improved vertical plane directivity characteristics.

[0028] Furthermore, because multiple radiating stubs 21 are arranged in parallel, cross-polarization does not occur, eliminating the need for conventional suppressors. This reduces the number of parts and assembly time, thereby lowering manufacturing costs.

[0029] Furthermore, since a second dielectric 4 with a lower dielectric constant than the first dielectric 3 is provided in a part of the radiating stub 21 and within the waveguide section 22, the propagation wavelength of radio waves in the waveguide section 22 and other parts is shortened, making it possible to miniaturize the radar antenna 1.

[0030] In this way, it becomes possible to keep the antenna size and manufacturing costs low while ensuring the necessary characteristics and performance (such as vertical plane directivity and cross-polarization suppression).

[0031] Although embodiments of this invention have been described above, the specific configuration is not limited to the embodiments described above, and any design changes, etc., that do not depart from the gist of this invention are also included. For example, in the above embodiment, the thickness of the center of the first dielectric 3 is almost zero, and the thickness t at both ends is set to 1 / 4 of the wavelength inside the tube, but the dimensions are not limited to this as long as the desired vertical plane directivity (vertical plane beam width) can be obtained. Also, if predetermined antenna characteristics (such as directivity characteristics and frequency characteristics) can be obtained, a cover may be provided on the front side of the housing 2. [Explanation of symbols]

[0032] 1. Radar antenna 2 cabinets 21 Radial stub 22 Waveguide section 3. First dielectric 4. Second dielectric

Claims

1. A plate-shaped, horizontally elongated housing is formed on its front side, and is groove-shaped, extending substantially perpendicular to the longitudinal direction of the housing, with a plurality of radial stubs arranged parallel to the longitudinal direction of the housing, A waveguide section formed within the housing, extending along the longitudinal direction of the housing and communicating with each of the radiating stubs, A first dielectric is provided within each of the aforementioned radiating stubs, wherein the central part of the radiating stub is thin and the ends are thicker in the longitudinal direction of the radiating stub, A radar antenna characterized by having the following features.

2. A second dielectric material having a dielectric constant smaller than that of the first dielectric material is provided within the waveguide section. The radar antenna according to feature 1.

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