JPS6019303A - Antenna - Google Patents

Abstract

PURPOSE:To obtain an antenna with less weight of wind pressure, light weight and low cost by constituting a reflection mirror of an antenna for circularly polarized wave with the 1st reflection mirror where many conductors are arranged in parallel and the 2nd reflection mirror where many conductors orthogonal to the former conductors are arranged in parallel. CONSTITUTION:The reflection mirror reflecting a radio wave irradiated from a primary radiator 6 is constituted by the 1st reflection mirror 4 where many conductors are arranged in parallel in vertical direction so as to be circumscribed with a paraboloid of revolution taking the primary radiator 6 as a focus and the reflection mirror 5 where many conductors are arranged so as to be orthogonal to the conductors of the reflection mirror 4 at a position apart by lambda/8 from the reflection mirror 4, and the reflection mirrors 4, 5 reflect respectively a polarized wave in parallel with the conductors and transmit the polarized wave orthogonal thereto. The path difference of propagating paths 7, 8 of the reflected wave irradiated to free space can be (n+1/4)lambda. Since said conductors are made of aluminum so as to attain light weight and wind free from passing through the reflection mirrors, the weight due to wind pressure is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a circularly polarized antenna mainly used in the SHF band.

Conventionally, this type of circularly polarized wave antenna, as shown in Fig. 3 and converts it into a plane wave, which is then radiated into free space. The reflecting mirror 3 is a metal plate formed into a paraboloid of revolution, and the primary radiator 2 is placed at the focal point of the reflecting mirror 3.

The conventional antenna described above has a drawback in that the wind pressure load applied to the reflecting mirror 3 is large. For example, diameter 1.2. m.

The pressure exerted on the antenna by the wind at a speed of 40 m reaches approximately 150 kg. For this reason, it is necessary to use a sufficiently thick metal plate for the reflecting mirror 3 so as to be able to withstand the above-mentioned wind pressure, and furthermore, the frame for supporting and fixing it to the ground or a building must be sufficiently solid. As a result, the antenna is heavy.

And it is expensive. Furthermore, since there is a loss in the circularly polarized wave generator l, the gain of the antenna decreases by that amount.

An object of the present invention is to solve the two conventional disadvantages, and to provide an antenna that has less wind pressure load, has a simple structure, is lightweight, and is inexpensive.

The antenna of the present invention includes a primary radiator and a reflecting mirror that reflects radio waves radiated by the primary radiator and converts them into plane waves, wherein the reflecting mirror has a large number of conductive wires arranged in parallel. It is characterized by being composed of an array of first reflecting mirrors, and a second reflecting mirror in which a number of conducting wires are arranged in parallel at a predetermined interval from the first reflecting mirror so as to be perpendicular to the number of conducting wires. shall be.

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 2 is a side sectional view showing one embodiment of the present invention. That is, the reflecting mirror for reflecting the radio waves emitted by the primary radiator 6 is a mirror in which a large number of conducting wires are vertically arranged in parallel so as to circumscribe a paraboloid of revolution with the primary radiator 6 as the focal point. 1 reflecting mirror 4, and a second reflecting mirror 5 in which a large number of conducting wires are arranged in the horizontal direction so as to be orthogonal to the conducting wires of the first reflecting mirror 4 at a position separated by 1/8 from the first reflecting mirror 4. It consists of 3 is a front view of the first reflecting mirror 4, and FIG. 4 is a front view of the second reflecting mirror 5.

The first reflecting mirror 4 has the property of reflecting the polarized wave Pi in a direction parallel to the conducting wire, but allows the polarized wave P2 perpendicular thereto to pass through. Similarly, the second reflecting mirror 5 reflects the polarized wave P2. The reflected wave from the first reflecting mirror 4 and the reflected wave from the second reflecting mirror 5 both become plane waves and are radiated into the free space in front of the antenna, but their propagation paths have an input/4 difference. There is.

Now, as shown in Figure 5, polarized waves P1 and P2 are orthogonal to each other.
A polarized wave having an angle of 45° to the primary radiator 6 of FIG. 2 is applied to the first reflector 4. When radiated to the second reflecting mirror 5, the vertically polarized wave P1 whose polarization has been resolved is reflected by the first reflecting mirror 4, and the horizontally polarized wave P2 is reflected by the second reflecting mirror 5.
is reflected by the reflecting mirror 5. Since there is a difference of /4 between propagation paths 7 and 8, the two polarized waves have a phase shift of +45° on the time axis, as shown in FIG. Therefore, these two polarized waves are spatially combined in front of the antenna, and the antenna output wave becomes a circularly polarized wave.

The path difference between propagation paths 7 and 8 is not limited to input/4, but may be (n+1./4)8, provided that n is 0.
is an integer containing . Also, the path difference between propagation paths 7 and 8 is (
n −1/4 )λ, the phase of the polarized wave P2 is advanced by 45° with respect to the polarized wave P1, and the direction of rotation of the circularly polarized wave output from the antenna can be reversed.

The primary radiator 6 is, of course, composed of a first reflecting mirror 4 and a second reflecting mirror 5.
must be placed in a common focus. First reflecting mirror 4. The conducting wire of the second reflecting mirror 5 is made of aluminum, for example, and is lightweight, and since the wind easily passes through the reflecting mirror, the wind pressure load is significantly reduced compared to a conventional antenna. There is. Along with this, the required strength of the mount is also reduced, making the entire antenna extremely light/Ij
It is possible to provide an antenna that is lightweight, inexpensive, and uses less material. Furthermore, since no circularly polarized wave generator is used, the antenna gain is improved accordingly.

The above-mentioned first reflecting mirror 4. Although the second reflecting mirror 5 is a rotationally symmetrical reflecting mirror, it goes without saying that the present invention can also be applied to a so-called offset-type parabolic antenna using a part of a paraboloid.

Further, since the conducting wires of the first reflecting mirror 4 and the second reflecting mirror 5 only need to be orthogonal to each other, they may be inclined with respect to the ground as shown in FIG. 7. Nera ni, Thu 9; IJIJ
It is also possible to apply this to an antenna equipped with a sub-reflector, such as a Cassegrain antenna, for example.

As described above, in the present invention, a first reflecting mirror in which a large number of parallel conductive wires are arranged on a reflecting surface, and a second reflecting mirror formed by a large number of 11-row conducting wires orthogonal to the above-mentioned conducting wires are provided. [2] Two reflecting mirrors are arranged at a predetermined interval,
Since the radiators are arranged at the common focal point, the wind IL load is reduced, and it is possible to provide a lightweight, inexpensive, and high-performance circularly polarized antenna.

[Brief explanation of drawings]

FIG. 1 is a side sectional view showing an example of a conventional circularly polarized antenna, FIG. 2 is a side sectional view showing an embodiment of the present invention, and FIG. 3 is a first reflecting mirror of the above embodiment. inside view, fit, 4
The figure is a front view showing the second reflecting mirror of the above embodiment, FIG. 5 is a diagram showing the polarized wave applied to the primary radiator in the above embodiment, and FIG.
The figure is a diagram showing temporal changes in the polarized waves reflected from the first reflecting mirror and the second reflecting mirror 5 in the embodiment described above.
FIG. 1 is a front view showing another example of FIG. In the figure, 1: circularly polarized wave generator, 2: primary radiator 1, 3
: Reflector, 4: First reflector, 5: Second reflector, 6:
Primary radiator, 7.8: Propagation path. Applicant LI Hondenki Co., Ltd. Agent Patent Attorney Sumi 1 (1 Toshimune Figure 1 Figure 2 Figure 9- ヱi';

Claims (1)

[Claims] In an antenna comprising a primary radiator and a reflecting mirror that reflects radio waves radiated by the primary radiator and converts them into plane waves, the reflecting mirror has a ff1 structure in which a large number of conducting wires are arranged in parallel.
a second reflecting mirror in which a large number of conductive wires are arranged in parallel so as to be perpendicular to the plurality of conductive wires at a predetermined interval from the first reflecting mirror;
An antenna characterized by comprising a reflecting mirror.