JPH02130007A - Array antenna - Google Patents

Abstract

PURPOSE:To improve gain to be lowered because of the close arrangement of radiating elements, and to reduce an attaching area by arranging a parasitic element at an approximate center in the circumference of a circle. CONSTITUTION:Central conductor bars 2 to 5 consisting of the aluminum bar of 15.2mm in length and 1.3mm in diameter are arranged at regular intervals on the circumference of a circle of 35.4mm in radius on a grounding plate 1, and side conductor bars 6 to 9 consisting of the aluminum bar of 15.2mm in length and 3.5mm in diameter are arranged at positions 6mm apart from those respectively outward in radial directions. Then, the centers of the top loads 10 to 13 consisting of an aluminum disk of 44mm in diameter are connected respectively to the top end parts of the central conductor bars 2 to 5, and simultaneously, the prescribed surface of the aluminum disks 10 to 13 and the head parts of the side conductor bars 6 to 9 are connected, and the radiating elements are constituted. Besides, at the center of the circumference of a circle of 35.4mm in radius where these radiating elements are arranged, the aluminum bar 14 of 22mm in length and 3mm in diameter is arranged vertically, and simultaneously, the aluminum disk 15 of 30mm in diameter is connected to the top end of this aluminum bar 14, and the parasitic element is constituted. Thus, the attaching area can be made smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to an array antenna, and particularly to an array antenna in which a plurality of non-directional radiating elements are arranged on a circumference.

(Prior Art) An array antenna is an antenna in which a plurality of radiating elements are arranged and all or some of the radiating elements are excited, and is used to obtain arbitrary directivity or to measure the direction of incoming radio waves.

Conventionally, as an array antenna for omnidirectional measurement, there is an antenna in which a plurality of omnidirectional radiating elements are arranged on the circumference of a ground plate surface. In this array antenna, the directivity of the array antenna can be changed by changing the phase of the excitation signal so that the radiation beam phases of each radiating element are mutually reinforced in a desired direction. Furthermore, the direction of arrival of the incoming radio waves can be measured by combining signals induced in required radiating elements and detecting their levels or phases. Furthermore, this array antenna can be made extremely thin by providing top loading at the head of each element to shorten the antenna length. Further, for top loading, a disk having a required radius is generally used, and the center portion thereof is attached to the tip of the antenna element.

However, when installing an array antenna with a top-loading disk on a curved surface such as the top of an aircraft, if the area is large, the array antenna must be adjusted to fit the curved surface for each model of aircraft. There was a problem in that the manufacturing cost would be high. Furthermore, when mounting an array antenna, it is possible to create an array antenna that can be easily mounted on curved surfaces of various curvatures by reducing the area and arranging the radiating elements closely together. As the distance between the edges of the discs becomes smaller and mutual coupling increases, the radiant energy of each radiating element is absorbed by the other radiating elements, or the feeding impedance of each radiating element fluctuates. There is a problem in that the gain as an array antenna decreases.

(Objective of the Invention) The present invention has been made to solve the above-mentioned problems of the array antenna, and provides an array antenna that can improve the decrease in antenna gain caused by densely arranging radiating elements. The purpose is to

(Summary of the Invention) In order to achieve the above-mentioned object, in the present invention, a plurality of non-directional radiating elements are arranged on a circumference, and parasitic elements are provided at required parts inside the circumference.

(Example) Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIGS. 1(a) and 1(b) are a plan view and a sectional view taken along the line A-A, showing an embodiment in which the present invention is applied to a 106106O band four-element array antenna.

In the figure, reference numeral 1 is a grounding plate, and centers made of aluminum rods with a length of 15.2mm and a diameter of 1.3mm are placed at equal intervals on the circumference of the grounding plate 1 with a radius of 35.4mm. Conductor rods 2 to 5 are arranged vertically, and side conductor rods 6 to 9, each made of an aluminum rod with a length of 15.2 mm and a diameter of 3.5 mm, are placed vertically at a position 6 mm radially outward from these. The center of each of the top loads 10 to 13 made of an aluminum disk with a diameter of 44 mm is connected to the tip of the center conductor rods 2 to 5, and a predetermined surface of each of the aluminum disks 10 to 13 is connected to the side conductor rod 6. to 9 are connected to form a radiating element. In addition, an aluminum rod 14 with a length of 22 mm and a diameter of 3 mm is placed vertically at the center of the circumference with a radius of 35.4 mm on which these radiating elements are arranged, and at the tip of this aluminum rod 14 there is a wire with a diameter of 30 mm. A parasitic element is constructed by connecting the aluminum disks 15.

At this time, the bases of the central conductor rods 2 to 5 of the four radiating elements are insulated from the ground plate 1 and connected to a feed line such as a strip line or coaxial cable (not shown). Further, the bases of the side conductor bars 6 to 9 and the aluminum bar 14 of the parasitic element are directly attached to the ground plate 1, and these and the ground plate 1 are electrically connected.

The array antenna configured in this way consists of 2 to 5 aluminum rods.
．． 6 to 9 and aluminum disks 10 to 13 form four omnidirectional radiating elements, and the aluminum rod 14 and aluminum disk 15 form a parasitic element, and according to various experiments, the gain is negligible. It was confirmed that the gain was several dB higher than that of a conventional array antenna without a feeding element.

The reason why such an effect is obtained is not clearly known, but it is speculated that in the array antenna mentioned above, the parasitic elements are placed near each non-directional radiating element, so the parasitic elements emit non-directional radiation. It is thought that the gain of the array antenna was improved as a result of receiving a portion of the radiant energy of the elements and attenuating the radiant energy that influences each other of the radiating elements of the array antenna. Alternatively, a part of the radiant energy of the non-directional radiating element is induced in the parasitic element, and this energy is re-radiated, which equivalently acts like a reflector or waveguide to generate a non-directional radiating element in a predetermined direction. It is also thought that the gain of the array antenna has improved due to the increased radiated energy. Alternatively, it would not be unnatural to think that the gain of the array antenna is improved by both of these factors.

According to the array antenna configured in this way, the gain can be improved compared to the conventional antenna even if the non-directional radiating elements are densely arranged.

Further, the present invention may be modified as shown in FIG.

That is, FIG. 2 shows an example in which the present invention is applied to a six-element array antenna, in which six omnidirectional radiating elements 17 and 17 are arranged at approximately equal intervals on the circumference of the earth plate 16 centered at a certain point. 2
2 are arranged vertically, and parasitic elements 23 and 28 are arranged vertically near each of the omnidirectional radiating elements 17 and 22, and the omnidirectional radiating elements 17 and 22 and the parasitic element 23
A top load 29 to 40 is provided at the head of each of the top loads 29 to 28.

In this way, if a large number of non-directional radiating elements are arranged on a predetermined circumference, the distance between them will become very small and the mutual coupling will increase. By arranging them, the gain of the array antenna can be improved in the same manner as in the above embodiment.

Incidentally, in the above embodiment, top loading was provided at the head of each of the omnidirectional radiating element and the parasitic element, but since this top loading is intended to shorten the length of these elements, it may be provided as necessary. It's obvious that it's a good thing.

Furthermore, in the present invention, it is obvious that the shapes and dimensions of the aluminum rods and disks forming each element, and the arrangement thereof, can be modified in various ways if the above-mentioned speculations are taken into account.

Further, in the above-described embodiments, each element is formed of an aluminum rod and a disk, but it is obvious that the present invention is not limited to this.

(Effects of the Invention) As explained above, the present invention has a plurality of radiating elements arranged on a predetermined circumference, and a parasitic element is arranged inside the circumference of the plurality of radiating elements to reduce mutual coupling between the radiating elements. Because of this, the reduced gain can be improved by densely arranging the radiating elements, so the mounting is very effective in constructing an array antenna with a small area.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are a plan view and a sectional view taken along the line A-A of an array antenna showing one embodiment of the present invention. FIG. 2 is a perspective view of an array antenna showing a modified embodiment of the present invention. 1
...Earth plate, 2 to 5...Center conductor rod, 6 to 9
...Side conductor rods 10 to 13...Top load, 14...Aluminum rod. 15...Aluminum disc.

Claims (1)

[Scope of Claims] 1) An array antenna in which a plurality of non-directional radiating elements are arranged on a circumference, and a parasitic element is positioned approximately at the center of the circumference. . 2) In an array antenna in which a plurality of non-directional radiating elements are arranged on the circumference, a required number of parasitic elements are arranged inside the circumference to reduce mutual coupling between the radiating elements, thereby increasing the overall An array antenna characterized by improved gain. 3) An array antenna in which a plurality of omnidirectional radiating elements are arranged on a circumference, and a parasitic element is arranged near each omnidirectional radiating element.