JPH01188106A - Directivity variable device - Google Patents

Abstract

PURPOSE:To simply vary the directivity by arranging a planar prism made of plastic constituted by multi-stage forming in terms of plane of triangular pyramids nearly in parallel with the front face of the planar antenna and providing an angle adjusting mechanism adjusting minutely the fitting angle of the planar prism. CONSTITUTION:Plural stages of prisms 15a whose cross sections are triangular prisms in the planar prism 15 are formed as a plane incorporatedly. Then the planar prism 15 in this way is fitted to the front face of the planar antenna 12 mounted perpendicularly to ground and in parallel with the supporting post 11 by an angle adjusting mechanism nearly in parallel. Then the angle adjusting mechanism 16 is adjusted minutely and a satellite broadcast radio wave 17 is refracted so as to be made incident perpendicularly to the planar antenna 12. Thus, excellent reception state is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a directivity variable device for a high-gain antenna for frequencies higher than microwaves.

[Prior Art] A flat antenna for receiving satellite broadcasting requires that the direction of the broadcasting satellite be accurately faced, but direct mounting of the antenna requires time and effort to change the angle. Therefore, the method of installing the planar antenna to change the directivity while keeping the angle constant is to attach a variable phase shifter to each element of the antenna and use this to change the phase of power feeding to each element. is considered.

[Problems to be Solved by the Invention] However, in the case of the above method, the frequency of the radio waves received by the antenna is very high, approximately 12 [GHz], so the space in which the variable phase shifter is installed is narrow, and the variable phase shifter is difficult to install. It is difficult to realize this, as it requires a large number of control devices to control the phase.
Directivity is constant.

In this way, there is no way to change the directivity of a flat antenna for satellite broadcasting while keeping the mounting angle constant, and in the end,
The only way to install the antenna was to change its angle and face the broadcasting satellite.

This invention was made in view of the above circumstances,
An object of the present invention is to provide a directivity variable device that can easily change the directivity of an antenna for satellite broadcasting, etc., while keeping the angle constant.

[Means and effects for solving the problem] The present invention provides a planar prism made of plastic made of triangular prisms formed in multiple stages in a plane and disposed substantially parallel to the front surface of a planar antenna. The installation is equipped with an angle adjustment mechanism that finely adjusts the angle so that the ultra-high frequency radio waves are refracted and incident perpendicularly to the planar antenna.

[Example code] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows its configuration, where 11 is a support column arranged perpendicular to the ground, 12 is a planar antenna, 13 is a mounting bracket for attaching the planar antenna 12 to the support column 11 in parallel, and 14 1 is a power feeding unit that feeds power to the planar antenna 12;
5 is a transparent plastic planar prism formed by forming triangular prisms in multiple stages; 16 is a planar prism 15 attached substantially parallel to the front surface of the planar antenna 12;
The planar prism 15 is attached with an angle adjustment mechanism that finely adjusts the angle as shown by arrow P, and 17 is a satellite broadcasting radio wave sent from a broadcasting satellite (not shown).

Next, the configuration of the planar prism 15 will be explained.

The plane prism 15 is basically formed in a planar manner by integrating a plurality of stages of prisms 15a having a triangular prism cross section as shown in FIG. Now, when the apex angle of the prism 15a is α and the refractive index is n, and the satellite broadcasting radio wave 17 with the wavefront AA' is incident, the satellite broadcasting radio wave 17 is refracted by the deflection angle θ shown in the figure, and the wave with the wavefront BB' and is ejected.

Assuming that all these angles are sufficiently small, the electrical distances between AB and A'B' are equal. The wavefront of A' passes through the length α of the prism 15a, whereas the wavefront of A passes through the length (θ+α) in the air. Therefore, prism 1
If the material of 5a is plastic and its dielectric constant is ε, then the refractive index n is nmF''. Therefore, the angle of deflection θ is θ-( (T"-1)α...It is given by (2).

In a state where the incident wave and the outgoing wave of the satellite broadcast radio wave 7 to the prism 15a are symmetrical with respect to the median of the apex angle α, the distance passing through the wave surface AB is r 2J′TI sin Ca/ 2) J , The distance passing through the wavefront A'B' is r2. i'5in((θ+α
)/2) J. Here, if the prism 15a is moved from a state where the incident radio wave and the emitted radio wave are symmetrical to an inclined state, the distance passing through the wave surface AB remains the same, but
The distance through the wavefront A'B' increases by the inverse cosine factor. Therefore, in a state where the incident radio wave and the emitted radio wave of the prism 15a are symmetrical, the distance that the radio wave passes through the wavefronts A' and B' and the deflection angle θ are minimized.

The deflection angle θ at this time is J7sin(α/2) −5in((θ+a)/2)
- given by (3). Therefore, the above (1
) is obtained by replacing the sine of equation (3) with an angle.

Here, using the above equation (3), assuming that the material of the prism 15a is acrylic, its dielectric constant ε-2.5 CF/m], and the apex angle α-45'', the angle θ-29.5@ is obtained.

If the angle with respect to the radio satellite broadcasting wave 17 incident on the prism L5a is shifted from this symmetrical position, the value of the angle θ becomes larger. Here, assuming that the wavefront BB' is perpendicular to the ground, by tilting the prism 15a,
This means that the elevation angle of the plane wave of the wave surface AA' can be adjusted within a range of 29.5 degrees or more.

By the way, the receiving antenna of a broadcasting satellite has a power of about 12 [GHH].
0.4 [m
An opening area of 21 or more is required.

In order to irradiate the entire aperture of the antenna with broadcast radio waves refracted by the prism 15a having the shape shown in FIG. 2 above, the length of one side of the prism 15a) must be
A length of in7 or more is required, and the prism surface needs to have an area of at least 0.6 to 0.7 [m2], taking into consideration the variable state of the angle. Such a large prism is not suitable for mounting on the front surface of a satellite broadcasting antenna, so an angle adjustment mechanism 16 having a similar function is mounted instead.

The angle adjustment mechanism 16 is constructed by forming triangular prisms in multiple stages on a plane, as described above and as shown in FIG.

FIG. 3(a) shows an example of a configuration in which only one side is serrated and the other side is flat. In the figure, the apex angle α is 45°.

Further, FIG. 3(b) shows a configuration example in which the triangular prisms having an isosceles triangular cross section shown in FIG. 2 are arranged linearly along their center lines. In this case, the plane prism 15 has a sawtooth shape that is symmetrical on both the front and back surfaces, and its apex angle is 60''.
It is.

Further, FIG. 3(c) shows an example of a configuration in which triangular prisms are alternately arranged so that one side of each of two adjacent triangular prisms forms a common plane. Here, the plane prism 15
After all, both the front and back sides have a sawtooth shape, and the apex angle is 60°.

Although some configuration examples have been shown above, the angle of the apex angle and the corresponding corners of each of the two corner angles can be designed completely differently, and the number of steps of the triangular prism, that is, the number of serrated teeth. The more the plane prism 15
The volume of can be reduced. In this case, if the coupling portions of each stage of the triangular prism are carefully designed so that there is no phase disturbance when the plane wave of the incident wave passes through the prism surface of the plane prism 15, the radio wave passing efficiency will not be significantly reduced. do not have. Note that as the plastic constituting the planar prism 15, a material that causes little loss when passing radio waves, such as polyethylene, Teflon, acrylic, or polystyrene, is used.

As shown in FIG. 1, the planar prism 15 having the above-mentioned configuration is attached almost parallel to the front surface of the planar antenna 12, which is attached perpendicular to the ground and parallel to the support column 11, by means of the angle adjustment mechanism 16. Finely adjust the adjustment mechanism 1G to transmit satellite broadcasting radio waves 17 from the broadcasting satellite to the flat antenna 1.
If the beam is refracted so as to be incident perpendicularly to the beam 2, good reception conditions can be obtained.

[Effects of the Invention] As detailed above, according to the present invention, a plastic planar prism formed by forming triangular prisms in multiple planar stages is disposed approximately parallel to the front surface of a planar antenna, and The planar prism is equipped with an angle adjustment mechanism that finely adjusts the angle so that the ultra-high frequency radio waves are refracted and incident perpendicularly to the planar antenna. It is possible to provide a directivity variable device that can easily change the directivity of the antenna while keeping the angle fixed by only making minor adjustments to the angle.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, with Fig. 1 showing the overall external configuration, Fig. 2 showing the principle of refraction of a prism, and Fig. 3 showing an example of the configuration of a plane prism. be. 11... Support column, 12... Planar antenna, 13...
・Mounting bracket, 14...Power supply part, 15...Plane prism, 1B...Angle adjustment mechanism, 17...Satellite broadcast radio wave. Figure 1

Claims (1)

[Claims] A planar prism made of transparent plastic constituted by triangular prisms formed in multiple stages in a planar manner, and the planar prism is mounted substantially parallel to the front surface of a planar antenna, and the mounting angle of the planar prism with respect to the planar antenna is adjusted. A directivity variable device characterized by comprising an angle adjustment mechanism for fine adjustment.