JPH0349448Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention is a parabolic antenna, a Cassegrain antenna, and various offset antennas used in radio relay lines in the microwave band and submillimeter wave band, and is wind-resistant, rain-resistant, and snow-resistant. This invention relates to an improvement of an aperture antenna equipped with a soft sheet-like radome (hereinafter referred to as a sheet radome) for use in commercial applications.

[Conventional technology]

Conventionally, as an example of an antenna for the above purpose, the fourth
The parabolic antenna with a seat tread dome shown in the figure has been put into practical use. The antenna shown in FIG. 4 basically consists of a main reflector 1, a primary radiator 2, a column 3, and a back structure 4, to which a flexible body 5 and a radome 6 are added. In Fig. 4, the shield body 5 is used to improve the wide-angle radiation characteristics (especially the F/B ratio) and as a support for mounting the radome 6. It is used to alleviate the deterioration of radiation characteristics caused by snow.

Traditionally, radomes have been made of hard materials such as single-layer FRP sheets and sand german boards, but since these deteriorate the radiation characteristics, in recent years, woven fabrics such as Tetron and nylon have been used. Soft composite dielectric sheets are often used, such as those coated with weather-resistant rubber or woven glass fibers treated with Teflon.

[Problem that the invention attempts to solve]

However, in antennas equipped with these sheet radomes 6, the radome is soft, so when strong winds blow, the radome bends inward and hits the primary radiator 2, causing damage, and the flexible body 5 and even the reflector 1 are damaged. give distortion. As a countermeasure to this problem, if the height of the shield plate 5 is increased or the strength is increased, the reflection of radio waves by the shield body 5 will increase, and it will be necessary to install a radio wave absorber to avoid this, resulting in cost and weight problems. It has some disadvantages, such as being disadvantageous.

As an example of a countermeasure for this purpose, conventionally, as shown in Fig. 5, a cylindrical (periscope-like) air intake part 7 is provided at the bottom of the antenna. In some cases, the air entering from the intake port 7 increases the air pressure inside the antenna, balances it with the external wind pressure, and alleviates the deflection of the seat tread dome 6.

However, this method is highly effective when the wind is blowing from the front, but when the wind is blowing diagonally forward or from the side, the amount of air taken in is small and the effect is not sufficient, causing large deflection of the radome 6. There were flaws.

Therefore, the aperture antenna of this invention was developed in order to solve these drawbacks, and also aims to improve the wide-angle radiation pattern.

[Means for solving problems]

The aperture antenna of this invention has semi-cylindrical or semi-conical covers on both sides of the shield body 5 to which the seat tread dome 6 is attached, which are shaped like a human's ears when viewed from the front of the antenna. The antenna is characterized in that the intake port 7 is provided a predetermined distance away from the opening surface of the antenna toward the main reflecting mirror 1.

[Effect]

In this invention, the air intake portions 7' provided on both sides of the shield body 5 can be used not only for wind blowing from the front but also for wind blowing from the sides. Since the wind is introduced into the antenna from the portion 7', the deflection of the radome 6 is alleviated and the desired function is achieved. In addition, the air intake portion 7' is configured so that the radio waves that are diffracted at the opening surface of the antenna, that is, the tip of the shield plate 5 and enter the antenna, and the radio waves that enter the antenna from the air intake port 7' cancel each other. If it is provided at a suitable position, it is possible to reduce side lobes.

〔Example〕

FIG. 1a is a side view (partially sectional view) of the antenna of this invention, and FIG. 1b is a front view of the same.

In Fig. 1, 1 is the main reflector, 2 is the primary radiator, 3 is the column, 4 is the back structure, 5 is the shingle body,
6 is a seat radome, and 7' is an air intake portion having a cylindrical or semiconical cover.

In this aperture antenna, the air intake portions 7' are attached to both sides of the flexible body 5, like human ears when viewed from the front of the antenna, as shown in Fig. In the position in the depth direction, radio waves arriving from the side are canceled because the component entering the antenna from the opening at the tip of the shielding plate and the component entering from the air intake port 7' are reversed in phase. It was set up in a place where they could be happy. If the air intake portion 7' is provided as described above, even if the antenna receives wind from diagonally in front or from the side, the air intake portion 7' on the side from which the wind is blowing will naturally receive the air from the air intake portion 7'. Even if the air flows in and creates a negative pressure at the opening surface, the seat radome 6 will expand due to the pressure from inside, and the radome 6 will hit the primary radiator 2 and be damaged, or the radome 6 will bend. Distortion of the flexible body 5 and the reflecting mirror 1 can be avoided.

In addition, as mentioned above, the position of the air intake portion 7' is such that the radio waves arriving diagonally from the front are divided into two components: a component that enters the antenna through the opening at the tip of the shield body 5, and a component that enters the antenna from the air intake port 7'. When set to cancel, the radiation level in the wide-angle direction is reduced,
An antenna with an excellent wide-angle radiation pattern can be realized.

Furthermore, even if the air intake portion 7' is not located at a position where the above-mentioned cancellation occurs due to the surrounding structural members, the antenna of this invention can still absorb the radio waves diffracted at the tip of the shield body 5. Since the component directed toward the rear of the antenna is suppressed by the air intake portion 7', it is possible to improve the F/B ratio characteristic of the antenna.

In the above explanation, a parabolic antenna having a rotationally symmetrical reflector was shown as an example of an antenna, but this invention is not limited to this, and a rotationally symmetrical Cassegrain antenna or Gregorian antenna shown in FIG. It is obvious that the present invention can also be applied to multi-reflector antennas such as the following. 1~ in Figure 2
7' corresponds to the same item as in FIG. 1, and 8 is a sub-reflector.

Furthermore, apart from improving damage to the sheet radome 6 due to contact with the primary radiator 2 and the sub-reflector 8, this invention can also be applied to an offset antenna having a non-rotationally symmetrical reflector as shown in FIG. It is clear that it is possible.

[Effect of idea]

As described above, according to this invention, by providing the air intake ports 7' on both sides of the antenna shield 5, the antenna can be protected against wind blowing diagonally forward or from the side. Air can be introduced into the interior, and the sheet radome 6 can be inflated to avoid damage caused by flapping of the radome 6, and distortion of the flexible body 5 and the main reflector 1 due to large deflection of the radome 6 can be avoided. At the same time, since the side lobe level of the antenna can be lowered even for radio waves arriving diagonally forward or from the side, good radiation characteristics can be obtained, which is extremely effective.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of a parabolic antenna showing one embodiment of the antenna of this invention, Fig. 1a is a side view (partial sectional view), Fig. 1b is a front view, Fig. 2,
FIG. 3 is a schematic configuration diagram showing another embodiment of this invention, and FIG. 2 is a diagram showing an example of a Cassegrain antenna.
Figure 3 shows an example of an offset antenna, Figure 4 shows an example of an offset antenna.
5 are cross-sectional views showing the structure of a conventional antenna. In the figure, 1 is the main reflector, 2 is the primary radiator, 3 is the column, 4 is the back structure, 5 is the shingle body, 6 is the seat radome, 7' is the air intake, and 8 is the sub-reflector. It is. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

Claims (1)

[Scope of utility model registration request] In an aperture antenna in which a flexible sheet-like radome is attached to a flexible body provided at the opening of the main reflector so as to cover the opening, a flexible sheet-like radome is mounted on both sides of the flexible body and in front of the antenna. An aperture antenna characterized by having an air intake portion with an open, for example, semi-warhead-shaped or semi-conical cover.