JP4044870B2 - Antenna device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an antenna device, and more particularly to an antenna whose radiation direction can be rotated 360 degrees.
[0002]
[Prior art]
Conventionally, as an antenna of a radar apparatus, a slot array antenna in which a large number of slots 10 shown in FIG. 4 are arranged, an array antenna composed of microstrip patch antennas that are planar antennas, and the like have been known. The radar device is usually a pulse radar, and a magnetron is used for the transmitter. The magnetron is capable of microwave oscillation with a large peak power relatively easily and is suitable for a pulse radar device. Thus, when it is possible to cover a transmitter with a single oscillator, the antenna apparatus is preferably an antenna having a form where a power feeding unit is provided at one place and the microwave power supplied therefrom is distributed to each antenna element. . As shown in FIG. 4, the slot array antenna has a structure in which a plurality of slots 10 correspond to the respective antenna elements, and a necessary directivity gain is obtained by combining them. Also in the case of a microstrip patch antenna used in a radar apparatus, the feeding point is a single point, and power is distributed to each patch antenna element from there by a microstrip line.
[0003]
Further, the radar apparatus needs to rotate an antenna having a narrow directivity in the horizontal direction by 360 degrees in the horizontal direction. Therefore, it has been common to use a rotary joint that is a transmission line having a rotation mechanism. Therefore, even when a planar antenna is used, the microwave feeding point is limited to one point installed at the rotation center of the rotary joint.
[0004]
Note that the microwave radiated from an antenna of a general marine radar apparatus is a horizontally polarized wave having a polarization plane in a direction perpendicular to the direction of gravity.
[0005]
The technology related to microwave feeding and polarization conversion as described above is, for example, disclosed in Japanese Patent Application Laid-Open No. 2001-185946, in which microwave power is supplied to an antenna using a rotary joint and polarization conversion of a radiated radio wave is performed. (Patent Document 1). This feeds power to a sub-reflecting mirror that is electromagnetically coupled using a feeding probe as a center axis of rotation, and the main reflecting mirror of the antenna has a polarization conversion function. Examples of supplying power without using a rotary joint include, for example, JP-A-6-37537 (Patent Document 2) and JP-A-8-293721 (Patent Document 3). In the former, the output of the waveguide is radiated as circularly polarized light from the radiating element through a flat transmission space and converted to linearly polarized light by the polarization converting element. The polarization plane is controlled by rotating the polarization converting element. It is realized by letting. The latter collects received signals from antenna elements provided on a dielectric plate, which is a rotating part, at a feeding point and transmits them to a re-receiving part provided in a fixed part by radio waves.
[0006]
[Patent Document 1]
JP 2001-185946 A [Patent Document 2]
JP-A-6-37537 [Patent Document 3]
Japanese Patent Laid-Open No. 8-293721
[Problems to be solved by the invention]
In recent years, the development of microwave semiconductor elements has progressed, and transmitters using microwave semiconductor elements as oscillators instead of magnetrons have been used for oscillators of radar devices. However, it is impossible to obtain microwave power equivalent to one magnetron with one semiconductor element. Therefore, in a transmitter using a semiconductor element as an oscillator, a microwave power synthesizing device is essential. However, the configuration in which the microwave power is combined by the power combiner and then distributed again to the transmitting antenna increases the power loss of the combiner and the like, which is not a preferable means. Further, when the antenna is rotated, if a conventional method of feeding power by a rotary joint is used, a device for setting the feeding point as the rotation center of the rotary joint is also necessary.
[0008]
On the other hand, as a method that does not use a rotary joint, it is conceivable to load semiconductor elements on each antenna element of a planar antenna and synthesize microwaves radiated from each antenna element in space. There is a problem that means for supplying power is difficult, and the size of the entire antenna is large and heavy due to components and the like for releasing heat generated by the semiconductor element, so that the rotational drive mechanism becomes large.
[0009]
An object of the present invention is to solve the above-described problems and to realize an antenna device having a plurality of microwave feeding points and capable of rotating the microwave radiation direction by 360 degrees with respect to the feeding points.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 includes a reflector, a primary radiator that radiates or receives circularly polarized waves, and a circularly polarized wave that is radiated from the primary radiator during transmission. A polarization converter that converts the linearly polarized light that has been reflected and incident on the reflecting plate into a circularly polarized wave during reception, and the reflecting plate and the polarization converter are integrated with each other. is, in the antenna device having a mechanism for rotating the approximate center of the primary radiator as a rotation axis, said primary radiator is constituted by a plurality of microstrip patch antennas, the plurality few microstrip patch antenna was disposed on the bottom surface of the housing, on the casing, Ru der those characterized by being rotatably arranged said polarization converter and the reflecting plate in the horizontal direction.
[0011]
The invention according to claim 2 is a primary radiator that radiates or receives circularly polarized waves, and converts circularly polarized waves radiated from the primary radiator to linearly polarized waves during transmission and is incident upon reception. and a reflecting plate for a polarization converter having a reflection surface for converting the linearly polarized to a circularly polarized wave, the reflection plate, provided with a mechanism for rotating the approximate center of the primary radiator as a rotation axis In the antenna device, the primary radiator is composed of a plurality of microstrip patch antennas, the plurality of microstrip patch antennas are arranged on a bottom surface of the casing, and the reflector is horizontally disposed on the casing. It is characterized by being arranged so as to be rotatable .
[0012]
Further, the invention according to claim 3 is the antenna device according to claim 1 or 2, wherein the primary radiator includes a plurality of microstrip patch antennas that radiate or receive linearly polarized waves, and the microstrip at the time of transmission. The linearly polarized wave radiated from the strip patch antenna is formed into a circularly polarized wave, and at the time of reception, it is composed of another polarization converter that converts the circularly polarized wave into a linearly polarized wave. It is arranged at the bottom of the body, and the other polarization converter is arranged in the space inside the casing on the microstrip patch antenna .
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic structural view showing a first embodiment of the present invention, FIG. 1 (a) is a perspective view, (b) is a plan view, (c) is a front view, and (d) is A in FIG. It is sectional drawing in the -A 'line. The present embodiment is an antenna device for a 9.4 GHz band radar device, which transmits and receives horizontally polarized microwaves having a polarization plane perpendicular to the direction of gravity. The primary radiator 3 includes a plurality of microstrip patch antennas (for example, four), and an in-phase circularly polarized wave is excited. Although not shown, an oscillator using a semiconductor element and its output It is connected to an amplifier that amplifies by branching and a duplexer. The primary radiator 3 is attached and fixed to the housing 4.
[0014]
The reflector 1 and the polarization converter 2 are supported so as to be rotatable integrally with a vertical line (center axis) passing through the approximate center 9 of the primary radiator 3 as shown in FIG. ing. The rotation is driven by a motor 5 attached to the housing 4, and only the reflector 1 and the polarization converter 2 rotate 360 degrees on the housing 4 in the horizontal direction.
[0015]
The polarization converter 2 is a device that converts between circularly polarized waves and linearly polarized waves, and has a structure in which several metal plates are arranged at specific intervals. In the present embodiment, a metal plate is used, but a dielectric plate may be used, for example.
[0016]
The length of the opening surface of the reflector 1 is about 30 cm, the directivity is about 6 degrees, and the microwave is transmitted and received with a sharp directivity in the horizontal direction. When transmitting radar radio waves (microwaves), the circularly polarized light radiated from the primary radiator 3 is converted into a linearly polarized wave by the polarization converter 2 and reflected toward the target by being reflected by the rotating reflector 1. Is done. Since the polarization converter 2 and the reflecting plate 1 rotate as a unit, the radiated microwave becomes horizontal polarization whose polarization plane is perpendicular to the direction of gravity. During reception, received signals that are horizontally polarized waves are collected by the reflector 1, converted from linearly polarized waves to circularly polarized waves by the polarization converter 2, and received by the primary radiator 3. At this time, the rotation axis of the reflecting plate 1 is in the direction of gravity.
[0017]
By configuring in this way, even when the primary radiator is composed of a plurality of microstrip patch antennas, if they are set to excite circularly polarized waves in the same phase, microwaves from a plurality of feeding points Can be synthesized in space, and an antenna device capable of transmitting and receiving horizontally polarized waves in the rotation direction can be realized.
[0018]
FIG. 2 is a front view of a second embodiment of the present invention, and 8 is a reflector having a function of a polarization converter. Although not shown, the primary radiator 3 is installed in the housing 4 as in the embodiment of FIG. The polarization converter installed in the embodiment of FIG. 1 is not provided in this embodiment. Instead, the reflecting plate 1 has a structure having a polarization conversion function. In order to realize such a function, in this embodiment, metal irregularities are provided on the surface of the reflector 1 at predetermined intervals. The polarization conversion function can be realized not only by the metal unevenness but also by the dielectric unevenness. As in the case of FIG. 1, the operating mechanism excites the circularly polarized wave with the primary radiator 3 during the transmission of the microwave, and converts the circularly polarized wave into the linearly polarized wave with the reflector 8. Due to the rotation of the reflecting plate 1, a horizontally polarized wave having a horizontal polarization plane is radiated. Conversely, when receiving microwaves, the horizontally polarized waves are received by the reflector 8 and converted into linearly polarized waves and received by the primary radiator 3.
[0019]
By adopting such a structure, even when the primary radiator is composed of a plurality of microstrip patch antennas as in the first embodiment, if they are set to excite circularly polarized waves in the same phase, An antenna device that can synthesize microwaves from a plurality of feeding points in space and can transmit and receive horizontally polarized waves at any position in the rotational direction can be realized. In particular, in the present embodiment, since the reflection plate 8 has a polarization conversion function, only the reflection plate 8 needs to be rotated, the rotation drive mechanism can be downsized, and the antenna device can be downsized. It becomes easy to plan. Further, since it is not necessary to provide a polarization converter separately, it is easy to reduce the cost when mass production is performed.
[0020]
FIG. 3 is a cross-sectional view of the third embodiment of the present invention. In this embodiment, instead of the primary radiator 3 of FIG. A primary radiator composed of another polarization converter 7 for converting to a wave is used. With this configuration, in this embodiment, the primary radiator 6 that excites linearly polarized waves and the polarization converter 7 are integrated, and the primary radiator 3 that excites circularly polarized waves in the embodiment of FIG. 1. Is working. By providing a separate polarization converter 7 in this way, the primary radiator 6 that excites linearly polarized waves, which is easy to design and manufacture the primary radiator, is used, and the same characteristics as the embodiment of FIG. Can be obtained.
[0021]
In this embodiment, instead of the reflector 1 and the polarization converter 2, a reflector 8 having a function of a polarization converter can be used as shown in FIG. With this configuration, it is only necessary to rotate the reflector 8 as in the second embodiment, the rotational drive mechanism can be downsized, and the antenna device can be easily downsized. .
[0022]
【The invention's effect】
As described above, the antenna device of the present invention includes a primary radiator composed of a plurality of microstrip patch antennas, and has a plurality of microwave feeding points without using a rotary joint. An antenna suitable for a radar apparatus capable of rotating the microwave radiation direction by 360 degrees can be realized. It is particularly suitable when a semiconductor element is used as a transmitter.
[0023]
In addition, since the reflection plate 1 has a polarization conversion function, only the reflection plate 1 needs to be rotated, and the antenna device can be easily downsized.
[0024]
Further, the primary radiator may be either circularly polarized wave excitation or linearly polarized wave excitation, and there is an effect that the degree of freedom in design is large. In particular, the linearly polarized excitation primary radiator is easy to design and manufacture, and has an effect that an antenna device can be easily formed.
[Brief description of the drawings]
FIG. 1 is a structural view showing a first embodiment of the present invention, where (a) is a perspective view, (b) is a plan view, (c) is a front view, and (d) is an A-A view of (b). It is sectional drawing in a 'line.
FIG. 2 is a front view of a second embodiment of the present invention.
FIG. 3 is a cross-sectional view of a third embodiment of the present invention.
FIG. 4 is a diagram showing a slot array antenna for a radar apparatus according to a conventional example.
[Explanation of symbols]
1: reflector, 2: polarization converter, 3: 1 primary radiator, 4: housing, 5: motor, 6: 1 primary radiator, 7: polarization converter, 8: reflector, 9: 1 Outline center of secondary radiator, 10: slot

Claims (3)

Reflector, primary radiator that radiates or receives circularly polarized waves, and circularly polarized waves radiated from the primary radiator during transmission are converted to linearly polarized waves, and reflected and incident on the reflector when receiving and and a polarization converter which converts the circular polarization of the linearly polarized with the turned reflecting plate and the polarization converter is integrated to rotate the approximate center of the primary radiator as a rotation axis mechanism In an antenna device comprising:
The primary radiator is composed of a plurality of microstrip patch antennas,
An antenna device comprising: a plurality of microstrip patch antennas disposed on a bottom surface of a housing; and the reflector and the polarization converter disposed on the housing so as to be rotatable in a horizontal direction . A primary radiator that radiates or receives a circularly polarized wave, and a circularly polarized wave radiated from the primary radiator during transmission is converted into a linearly polarized wave, and an incident linearly polarized wave is converted into a circularly polarized wave during reception. and a reflecting plate for a polarization converter having a reflecting surface, the reflecting plate, in the antenna device having a mechanism for rotating the approximate center of the primary radiator as a rotation axis,
The primary radiator is composed of a plurality of microstrip patch antennas,
An antenna device , wherein the plurality of microstrip patch antennas are arranged on a bottom surface of a casing, and the reflecting plate is rotatably arranged on the casing in a horizontal direction . 3. The antenna device according to claim 1, wherein the primary radiator includes a plurality of microstrip patch antennas that radiate or receive linearly polarized waves, and a linear polarization that is radiated from the microstrip patch antennas during transmission. It consists of a separate polarization converter that converts waves into circularly polarized waves and converts circularly polarized waves into linearly polarized waves during reception .
The antenna device, wherein the plurality of microstrip patch antennas are arranged at a bottom of the casing, and the other polarization converter is arranged in a space in the casing on the microstrip patch antenna .

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