JPH0744382B2 - Array antenna - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an array antenna using a reflector, and more particularly to an array antenna in which the reflector has a ventilation structure.

(Prior Art) In an array antenna, a reflector is used to converge electromagnetic waves emitted by an antenna element in a desired direction and suppress radiation in an undesired direction.

If a conductive surface having no openings such as a metal plate is used as the reflector, a considerable wind pressure load is applied to the reflector. In that case, in order to maintain the reflector surface in the desired shape and prevent damage to the reflector, it is necessary to use a large-scale complex mechanical structure, and to rotate the antenna. A high output motor is required.

In order to reduce the wind pressure load on the reflector,
There is an example in which one collinear array 104 is alternately arranged with a column array 103 composed of an antenna element 101 and a power distributor 102 made of a conductive column as in the antenna shown in FIG. No. 1001).

In the example of FIG. 6A, the undesired beam 105 is suppressed and the beam 106 sufficiently lower than the desired beam 107 is obtained, as shown in FIG. 6B, due to the resonance phenomenon of the collinear array.

(Problems to be Solved by the Invention) In the above-mentioned conventional technique, the antenna of FIG. 6 has a small wind pressure load, but since the resonance phenomenon is used, its tuning adjustment is troublesome, and a collinear array having a complicated structure is used. Since it is a reflector, it is expensive. Further, in general, in antenna design, the antenna aperture amplitude distribution is designed to be different in each part of the antenna aperture in order to perform desired beam formation, so that the intensity of undesired radiation is also different in each part of the antenna aperture. Nevertheless, the above-mentioned conventional technique has a drawback that it is wasteful because the antenna element, the power distributor, and the reflector that provide a uniform suppression effect are arranged in the entire antenna aperture.

An object of the present invention is to eliminate the above-mentioned drawbacks and to provide an inexpensive array antenna with a low wind pressure load while maintaining the effect of suppressing unnecessary radiation leakage that penetrates the reflector.

(Means for Solving Problems) The present invention has the following configuration in order to achieve the above object. That is, in the array antenna of the present invention, a plurality of flat linear polarization linear arrays in which a plurality of antenna elements are linearly arranged are arranged at predetermined intervals and the linear arrays are arranged so that the antenna elements form a planar array. Arrays arranged in parallel, having conductive columns parallel to the linear arrays at a predetermined distance from the plane formed by the planar arrays between the linear arrays, and an array having conductive plates on both sides of each linear array In the antenna, for each linear array,
It is characterized in that any one, two, or all of the numbers, shapes, and dimensions of the conductive columns are changed according to the magnitude of the excitation amplitude distribution of each part of the array antenna aperture.

(Operation) The larger the number of conductive columns provided in the space between the conductive plates and the more the shape that closes the space,
Also, the larger the shape, the more the unwanted radiation can be suppressed, while the wind pressure load increases. Generally, in designing an antenna, the excitation intensity is designed to be different at each part of the antenna aperture in order to form a desired beam.

In many cases, the closer to the center of the antenna opening, the greater the excitation strength, and the closer to the peripheral portion, the smaller the excitation strength. The intensity of undesired radiation is high when the excitation intensity is high, and is low when the excitation intensity is low. Therefore, the degree of suppression of undesired radiation in a portion having a high excitation intensity is large, while the degree of suppression in a portion having a small excitation intensity is small, or the undesired radiation as a whole is suppressed without any particular suppression means. Sufficient suppression effect is obtained.

The present invention has been made with this point in mind, and the number of conductive columns in the antenna aperture where the excitation strength is large is large, the shape is large in the degree of suppression, or the size is large. While increasing the degree of suppression of undesired radiation, reduce the number of conductive columns in the part where the excitation intensity is small, or use a shape with a small wind pressure load,
When the wind pressure load as a whole is provided with a uniform distribution while the effect of suppressing undesired radiation is sufficiently obtained by reducing the size or not providing the conductive columns. It is intended to be reduced more than.
The grounds for achieving such an objective are as follows.
In FIG. 1B, when a linearly polarized wave having an electric field direction perpendicular to the paper surface is radiated from the antenna element 1, it is rearward due to a cutoff effect obtained by the conductive plate and the conductive column 4 included in the column array 3. Radiation (upward in FIG. 1B) is suppressed. This is because the conductive columns 4 are arranged in the longitudinal direction in the same direction as the electric field direction (arranged in parallel with the linear array). For example, if the space between the column arrays 3 is completely filled by increasing the number of conductive columns 4,
Radiation to the rear is extremely low, and the description on page 8 at line 19 to 9
In the example on page 4 line, a suppression effect of 50 dB or more is obtained.

(Example) Next, an example of the array antenna of the present invention will be described with reference to the drawings. FIG. 1 is a view showing the structure of the first embodiment of the present invention, FIG. 1 (a) is a perspective view, and FIG. 1 (b) is a plan view.

In this array antenna, column arrays 3 each composed of an antenna element 1 and a power distributor 2 and conductive columns 4 are alternately arranged. In the case of the present array antenna, for example, like the Taylor distribution, the amplitude near the center of the antenna opening is increased, and the amplitude is decreased toward the end, so the number of conductive columns 4 near the center of the antenna opening is increased. However, the amount is reduced toward the end. FIG. 2 is a partially cutaway perspective view of the column array 3 of the first embodiment, in which the antenna element 1 and the power distributor 2 are integrally processed to form a linear array antenna.

The power distributor 2 has a triplate structure, in which the dielectric spacers 6 are provided on both sides of the microstrip line 5, and the ground conductor plate 7 is provided outside thereof. The dielectric cover 8 is used to protect the antenna from rain, wind and the like.

The conductive columns 4 are arranged between the column arrays 3 so that radiation in an undesired direction is suppressed by the ground conductor plate 7 in FIG. 2 and the conductive columns 4 in FIG.

In this case, the ground conductor plate 7 of the triplate structure that constitutes the power distributor is the ground conductor plate.

Therefore, it is not necessary to separately provide a conductive plate, and there is an advantage that the manufacturing cost can be reduced accordingly.

In addition, the conductive columns 4 are arranged so that the space between the column arrays 3 is substantially equally divided in the direction in which the column arrays 3 are arranged.
Are arranged.

Further, in FIG. 1 (b), the point E is the equivalent radiation center of the antenna element 1 and the point R is the center of the conductive column.
By making the distance indicated by to be a length of approximately a quarter wavelength, the mirror image of the equivalent radiation center can be moved backward by a distance of a half wavelength, so that it is forward (in the direction of the arrow in FIG. 1 (b)). However, as a result, in-phase synthesis is performed, and as a result, backward unwanted radiation can be efficiently suppressed.

Although the embodiment of FIG. 1 shows the case where the number of the conductive columns 4 is 1 to 4, the degree of suppression of undesired radiation, the antenna aperture distribution, the spacing of the column array 3, and the conductive columns 4 are set. Of course, the number of conductive columns in each part of the antenna varies depending on the thickness or shape. For example, if the spacing between column arrays is 0.8λ (λ is the wavelength), the width of the ground conductor plate is 0.5λ, and the diameter of the cylindrical conductive column is 0.05λ, the beam gain in the desired direction and the undesired The difference from the gain of the beam in the direction can be obtained by about 30 dB when the number of the conductive columns is 4, and about 20 dB when the number of the conductive columns is 2.

FIG. 3 is a plan view of the second embodiment of the present invention, in which a thin conductive column 9 and a thick conductive column 10 are arranged between the column arrays 3. In the case of FIG. 3, the thickness of the conductive column is changed to correspond to the antenna aperture distribution. FIG. 4 is a perspective view of a conductive column according to a third embodiment of the present invention, which is effective when an opening distribution such as Taylor distribution is given in the longitudinal direction of the column array, and has a high amplitude center. The part is thick. FIG. 5 is a perspective view of a set of four conductive columns according to the fourth embodiment of the present invention, which is a combination of a long conductive column 11 and a conductive column 12 shorter than the conductive column 11 by a broken line portion. Thus, the same effect as that of the third embodiment is obtained.

Although the four embodiments have been shown above, a combination of the above embodiments is also possible depending on the antenna aperture distribution and the array configuration. Further, as the conductive column, not only the column but also other shapes such as a square column have the same effect.

The above-mentioned embodiment has a mechanism for indicating the column array 3 and the conductive columns 4, 9 and 10 but it is not related to the essence of the present invention and therefore the description thereof is omitted.

(Effects of the Invention) As described above, according to the present invention, undesired reflection is caused by changing the number of conductive columns having a simple shape, the shape, and the number of each part in accordance with the antenna aperture amplitude distribution. While effectively suppressing, the number of conductive columns of the entire antenna can be reduced compared to the case where the same type of conductive columns are uniformly arranged.
There is an effect that the wind pressure load can be reduced and the price can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention, FIG. 1 (a) is a perspective view thereof, FIG. 1 (b) is a plan view thereof, and FIG. 2 is a description of a first embodiment of the present invention. 3 is a plan view of a second embodiment of the present invention, FIG. 4 is a perspective view of a conductive column of a third embodiment of the present invention, and FIG.
FIG. 6 is a perspective view of a conductive column according to a fourth embodiment of the present invention, FIG. 6 is a diagram showing a conventional antenna, FIG. 6A is a perspective view thereof, and FIG. 6B is an explanation of the effect of a reflector. FIG. 3 is a directional characteristic diagram of an antenna for. 1,101 …… Antenna element, 2,102 …… Power distributor, 3,103
…… Column array, 4,9,10,11,12 …… Conductive column, 5 ……
Microstrip line, 6 ... Dielectric spacer, 7
...... Ground conductor plate, 8 ・ ・ ・ Dielectric cover, 104 ・ ・ ・ Coriner array, 105 ・ ・ ・ Undesired beam, 106 ・ ・ ・ Uncontrolled undesired beam, 107 ・ ・ ・ desired beam

Claims (3)

[Claims] 1. A linear array of linearly polarized linear arrays in which a plurality of antenna elements are linearly arrayed are arranged at predetermined intervals, and the linear arrays are arranged in parallel so that the antenna elements form a planar array. An array antenna having conductive columns parallel to the linear array at a position at a predetermined distance from the plane formed by the planar array between the linear arrays and having conductive plates on both sides of each linear array, One or two or all of the number, shape and size of the conductive columns are changed for each linear array according to the magnitude of the excitation amplitude distribution of each part of the array antenna aperture. Array antenna to do. 2. A conductive plate including a ground conductor plate included in a power distributor having a triplate structure configured to distribute power to each antenna element of the linear array or combine power from each antenna element. The array antenna according to claim 1, wherein the array antenna is a flexible plate. 3. An equivalent radiation center of the antenna element and a normal line from the equivalent radiation center in a direction perpendicular to a plane in which a plurality of the linear arrays are arranged so that the antenna element forms a planar array. 3. The distance between the conductive column located in the opposite direction to the radiation direction of and the closest to the equivalent radiation center is approximately one-quarter of the wavelength. The array antenna according to item (2).