JPH0646095Y2 - Array antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an array antenna, and in particular, to a structural improvement of an array antenna of a type in which the array antenna is arranged on a base and the base is mechanically rotated. Regarding

(Prior Art) As is well known, various types of array antennas are known, but the one targeted by the present invention is an array antenna arranged on a mechanically rotated base. . This type of array antenna may be used in a radome, but it may have an open structure that is not housed in the radome. For example, the one shown in FIG. 2 is known.

In FIG. 2, flat plate-like column arrays 8 are erected at appropriate intervals in a horizontal direction on a base (not shown),
A metal conductor rod (generally a metal pipe) 9 that is a reflector is erected between the column arrays. Here, the reason why the metal pipe is used as the reflector instead of the metal net or the metal plate is in consideration of wind pressure load. The structure of the column array 8 is as shown in FIG.

In FIG. 3, 3 is a rectangular printed circuit board,
On one surface of the printed circuit board 3 on one end side in the short side direction, a plurality of antenna elements, 1, ...
... is provided. In addition, on both sides of the printed circuit board 3 on the other end side in the lateral direction, the ground conductor plate 5a,
The same 5b is arranged via the dielectric spacers 4a and 4b.

That is, the power distributor 2 having a so-called triplate structure is disposed on the other end side of the printed circuit board 3 in the lateral direction, and the power distributor 2 and the plurality of antenna elements 1, 1, ...
… (For example, 10 dipole antennas) are connected by feed lines 7, 7 and so on. It is well known that each of the above elements is integrally configured by a microstrip line formed on the surface of the printed board 3. The entire surface is covered with the dielectric cover 6 to form the waterproof column array 8.

Therefore, regarding the array antenna shown in FIG.
In the figure, the front side of the column array 8 in the width direction is the radio wave direction (referred to as the front direction of the antenna). Therefore, the metal pipe 9 is provided at the rear end side of the column array 8 in order to suppress unnecessary radiation toward the rear. It is arranged on both sides, that is, both sides of the power distributor 2 and at a position retracted from the antenna element 1 by about 1/4 wavelength. This is a general configuration of this type of array antenna, and a predetermined beam scanning is performed by mechanically rotating a base that supports them in a horizontal plane.

Here, the arrangement relationship between the column array and the reflector in the conventional array antenna is as shown in FIG. The array antenna targeted by the present invention uses a metal pipe 9 as a reflector. When a metal net or a metal plate is used as the reflector, the reflector is flush with the front end of the power distributor 2. It is located in. Therefore, even when the metal pipe 9 is used as the reflector, as shown in the figure,
The metal pipe 9 is arranged on the same plane as the front end of the power distributor 2. As a result, the length of the feed line 7b is the distance from the antenna element 1 to the metal pipe 9, that is, about 1/4 wavelength.

The value of the depth width 12b of the column array 8 is as follows. If the wavelength is written as λ, the length of the feed line 7b is about 0.25λ, and the length of the power distributor 2 is about 0.25λ.
The depth width 12b is about 0.5λ.

(Problems to be solved by the invention) By the way, since the array antenna targeted by the present invention is mechanically rotated, it is necessary to apply a small wind pressure in order to reduce the size and weight of the antenna rotating mechanism. Is desired. This is especially important for open structures. Considering the antenna structure from this point of view, as is clear from FIG. 2, since the depth width 12a of the column array 8 is considerably larger than the thickness thereof, the wind pressure load in the lateral direction is greater than that in the front direction of the antenna. It will be considerably larger than that. That is, in this type of array antenna, generation of a predetermined amount of wind pressure is essentially unavoidable, but in order to reduce it, it is essential to shorten the depth width 12a of the column array 8.

Therefore, it is conceivable to shorten the distance 10 between the antenna element 1 and the metal pipe 9. However, in that case, not only the desired radiation pattern cannot be obtained, but also the input impedance of the antenna element 1 becomes very small, which makes impedance matching difficult.

The length of the power distributor 2 is currently about (about 0.
25λ), it is the minimum value, and if it is further shortened, insertion loss increases, so it cannot be adopted.

The present invention has been made in order to meet such a conventional demand, and an object thereof is to provide an array antenna capable of reducing the depth width of a column array and thereby reducing the wind pressure load.

(Means for Solving the Problems) In order to achieve the above object, the array antenna of the present invention has the following configuration.

That is, in the array antenna of the present invention, a plurality of antenna elements are arranged at one end side of the rectangular printed circuit board in the short side direction at appropriate intervals in the longitudinal direction, and the other end side in the short side direction is entirely covered in the longitudinal direction. A power distribution board with a triplate structure is placed across the board, and multiple antenna elements and power distribution boards are connected by power feed lines. In the array antenna, which is arranged at an appropriate interval, and the metal conductor rods, which are reflectors, are arranged on the side of the power distributor between the column arrays and at a position retracted by about 1/4 wavelength from the antenna element. The length of the feed line is shorter than the distance between the antenna element and the metal conductor rod.

(Operation) Next, the operation of the array antenna of the present invention configured as described above will be described.

The width of the column array is shorter than the conventional one because the length of the feed line is shorter than the distance between the antenna element and the metal conductor rod.

Therefore, the load of the wind pressure in the lateral direction can be made smaller than in the conventional case, and as a result, the antenna rotating mechanism can be made smaller and lighter.

The length of the feeding line is experimentally determined in consideration of the number of antenna elements and the influence on the radiation pattern.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an array antenna according to an embodiment of the present invention. The same components as those of the conventional example are designated by the same reference numerals and the description thereof will be omitted.

In the array antenna of the present invention, the length 11 of the feed line 7a is made shorter than the distance 10 (about 1/4 wavelength) between the antenna element 1 and the metal pipe 9, and the front end of the power distributor 2 is connected to the metal pipe 9. The front antenna element 1 side of the structure,
Therefore, the depth width 12a is made shorter than the conventional one.

Conventionally, as described with reference to FIG.
The length was about 1/4 wavelength, which is the same as the distance 10 between the antenna element 1 and the metal pipe 9. This is a result of determining the positional relationship between the power distributor 2 and the metal pipe 9 in accordance with the example of the positional relationship between the power distributor and the reflector when the metal net or the metal plate is used as the reflector. However, as a result of experiments, it has been found that when the reflector is the metal pipe 9, it is not necessary to follow the previously defined arrangement relationship. That is, even if the arrangement position of the power distributor 2 is moved to the antenna element 1 side so that the front end portion is located in front of the metal pipe 9, no significant influence on the radiation pattern which has been conventionally expected is recognized. Therefore, it has been found that the length 11 of the feed line 7a does not need to be 1/4 wavelength. Here, the length 11 of the feed line 7a is, of course, set within a range in which the influence on the radiation pattern can be ignored, but it is determined experimentally because it differs depending on the number of antenna elements 1 and the like.

Next, a concrete example of numerical values is as follows. As in the conventional example, the column array 8 serves as the antenna element 1.
If one dipole antenna is used, feed line 7a
The length 11 can be shortened to about 0.15λ. As a result, the depth width 12a of the column array 8 is 0.15λ + 0.25λ = 0.4.
It becomes λ and can be shortened to 80% of the conventional example.

(Effect of the Invention) As described above, according to the array antenna of the present invention, the feed line to the antenna element is made shorter than in the conventional example, so that the width of the column array can be made shorter than in the conventional example. As a result, the load of the wind pressure on the array antenna in the lateral direction can be reduced, the weight of the array antenna support mechanism can be reduced, and the antenna rotation mechanism can be reduced in size and weight.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an array antenna according to an embodiment of the present invention, FIG. 2 is a schematic perspective view showing a general configuration of an array antenna targeted by the present invention, and FIG. 3 is a column array structure. FIG. 4 is a partially cutaway perspective view, and FIG. 4 is a schematic sectional view of a conventional example. 1 ... Antenna element, 2 ... Power distributor, 3 ... Printed circuit board, 4a, 4b ... Dielectric spacer, 5a, 5b ... Ground conductor plate, 6 ... Dielectric cover, 7, 7a, 7b ... … Feeding line, 8…
… Column array, 9 …… Metal pipe, 10 …… Gap between antenna element and metal pipe, 11 …… Feed line length, 12a,
12b …… The depth of the column array.

Claims (1)

[Scope of utility model registration request] 1. A rectangular printed circuit board is provided with a plurality of antenna elements on one end side in the lateral direction at appropriate intervals in the longitudinal direction, and a triplate is arranged on the other end side in the lateral direction over the entire surface in the longitudinal direction. Although a power distributor having a structure is arranged and a plurality of antenna elements and power distributors are connected by power feed lines, a plurality of column arrays covered with a cover are arranged at appropriate intervals so that the printed circuit boards face each other. In the array antenna, in which the metal conductor rods, which are arranged in a row, are arranged laterally of the power distributor between the column arrays and at a position retracted by about 1/4 wavelength from the antenna element; The array antenna is characterized in that the length is shorter than the distance between the antenna element and the metal conductor rod.