JPH01248801A - Reflection mirror antennae - Google Patents

Abstract

PURPOSE:To realize a radiation pattern having an approximately equal beam width in a low frequency band and a high frequency band and to realize a radiation pattern having a rotation symmetry and a low intersection polarization level in the high frequency band by setting the inner diameter of a circular waveguide connected to a horn part to a special dimension. CONSTITUTION:A title reflection mirror antenna is provided with a primary horn 2 composed of a feeding port 3 to supply an electric power, a first waveguide (taper waveguide 4) connected to the feeding port 3, a second waveguide (circular waveguide 5) connected to the first waveguide and a horn part 6 to transmit and receive the electric wave connected to the second waveguide, and sets the inner diameter of the second waveguide to the dimension so that only the electric wave of a basic mode can be propagated in the low frequency band and the electric wage of the high order mode can be propagated besides the electric wave of the basic mode in the high frequency band. Thus, the primary horn 2 is excited only by the electric wave of the basic mode in the low frequency band and excited by the electric wave of a plural modes of the basic mode and the high order mode in the high frequency band.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a reflector antenna used in terrestrial public communications and satellite communications for transmitting and receiving radio waves in the microwave band or millimeter wave band.

[Conventional technology]

FIG. 4 is a configuration diagram of a conventional reflector antenna disclosed in, for example, Japanese Unexamined Patent Publication No. 52-156537. Figure 4 (
a) is a side view of the reflector antenna (in Figure 4)
In FIG. 0, which is a front view, 11 is a reflector that reflects radio waves, 12 is a primary horn that irradiates the reflector 11 to transmit and receive radio waves, and 13 is a power feeding port connected to the primary horn 12. For example, 13a is a power supply port for low frequency band, and 13b is a power supply port for high frequency band.

A conventional reflector antenna is configured as described above. For example, a spherical wave radiated from the primary horn 12 set at the focal point of the reflector 11 is converted into a plane wave by the reflector 11, and the radiated power is transmitted in the direction of travel of the plane wave. A strong radiation pattern can be achieved. Further, the plane wave incident on the reflecting mirror 11 along the traveling direction is reflected by the reflecting mirror 11 and then sent to the primary horn 12.
can be converged efficiently.

[Problem to be solved by the invention]

By the way, when using a conventional reflector antenna as shown in FIG. When the levels of are made approximately equal in the two frequency bands, the beam width of the secondary radiation pattern radiated from the reflecting mirror 11 changes depending on the frequency. Therefore, when irradiating a desired service area, it is possible to implement an optimal design that maximizes the minimum gain within the service area in either frequency band, but it is not possible to implement it in both frequency bands. Have difficulty.

On the other hand, the primary horn 12 has a shape with a large frequency change, and the level in the edge direction of the reflecting mirror 11 is changed in two frequency bands, for example, about -10 dB in the low frequency band,
In the high frequency band, by making the irradiation area of the reflecting mirror 11 equivalently small at -10 dB or less, the beam widths of the secondary radiation patterns can be made almost equal. However, in the high frequency band compared to the low frequency band,
It is necessary to irradiate the reflecting mirror 11 up to the low level of the radiation pattern of the primary horn 12 and even include the side lobes. There have been problems in that the secondary radiation pattern generated by this method becomes non-rotationally symmetric and the level of cross-polarization becomes high.

This invention was made to solve the above problems, and it is possible to realize a radiation pattern with almost equal beam width in the low frequency band and high frequency band, as well as rotationally symmetrical and cross-polarized radiation patterns in the high frequency band. The purpose is to obtain a reflector antenna that can realize a radiation pattern with a low wave level.

[Means to solve the problem]

The reflector antenna according to the present invention includes a power feed port 3 for supplying power, a first waveguide (tapered waveguide 4) connected to the power feed port 3, and a first waveguide connected to the first waveguide. The primary horn 2 includes a second waveguide (circular waveguide 5) and a horn section 6 connected to the second waveguide for transmitting and receiving radio waves. The inner diameter is dimensioned so that only fundamental mode radio waves propagate in the low frequency band, and in addition to the fundamental mode radio waves, higher mode radio waves also propagate in the high frequency band. be.

[Effect]

By setting the inner diameter of the second waveguide (circular waveguide 5) as described above, the primary horn 2 is excited by only fundamental mode radio waves in the low frequency band, and fundamental mode radio waves in the high frequency band. A part of the mode radio wave is at the connection between the first waveguide (tapered waveguide 4) and the second waveguide (circular waveguide 5),
At the connection between the second waveguide/tube (circular waveguide 5) and the horn section 6, it is converted into a higher-order mode radio wave, and is therefore excited by a multiple-mode radio wave of the fundamental mode and the higher-order mode.

[Embodiments of the invention]

FIG. 1 is a configuration diagram showing a reflector antenna according to an embodiment of the present invention. Figure 1 (a) is a side view of the reflector antenna, and Figure 1 (bl is its front view). A power supply port connected to the primary horn 2,
For example, 3a is a power feeding port for low frequency band power, and 3b is a power feeding port for high frequency band power.

FIG. 2 is a diagram showing the structure of a conical primary horn 2 which is a component of the reflector antenna of this embodiment. Figure 2 (
FIG. 2(a) is a side view of the primary horn, and FIG. 2(b) is a front view thereof. In the figure, 3 is a power feed port for feeding power, 4 is a tapered waveguide as a first waveguide, 5 is a circular waveguide as a second waveguide, and 6 is a horn part, each of which is continuous. and is connected. In this embodiment, the inner diameter of the circular waveguide 5 is dimensioned so that in the low frequency band, only radio waves in the fundamental mode TE and mode propagate, and radio waves in the higher order mode T M Ir mode do not propagate. ,
In addition, in the high frequency band, the dimensions are such that in addition to the T E t + mode, TM, - mode radio waves are also propagated. That is, based on these conditions, the inner diameter of the circular waveguide 5 is, for example, larger than 1.22 times the wavelength of the lowest frequency in the high frequency band, and 1.22 times the wavelength of the highest frequency in the low frequency band.
Exist within a range smaller than 22 times.

In the conical primary horn 2 configured as described above, radio waves in the low frequency band and high frequency band are fed from the power feed port 3 as the fundamental mode TE, , mode, and the low frequency band TE, , mode is fed. The radio waves propagate to the aperture surface without being converted into higher-order modes at the connection between the Taber waveguide 4 and the circular waveguide 5 and the connection between the circular waveguide 5 and the horn section 6, and The primary horn 2 is excited only by TE mode radio waves. Further, a part of the radio waves in the high frequency band TE mode is transmitted at the connection between the tapered waveguide 4 and the circular waveguide 5, and at the connection between the circular waveguide 5 and the horn section 6, respectively. TM, mode, and therefore the radio waves of TE, mode and TM, mode are propagated to the aperture surface of the horn section 6, and the conical primary horn 2 is converted into TE, mode and T.
It is excited by multi-mode radio waves with M, mode.

Furthermore, by changing the aperture angle of the Taber waveguide 4 and the length of the circular waveguide 5, the amplitude ratio and phase difference of the above two modes can be adjusted, so that desired values can be obtained. By designing this, it is possible to realize a radiation pattern that is rotationally symmetric and has a low cross-polarization level in a high frequency band.

Furthermore, by appropriately selecting the aperture angle and the aperture diameter of the horn portion 6, it is possible to realize a radiation pattern in which the beam width differs greatly between the low frequency band and the high frequency band. For example, Figure 3 shows the radiation pattern when exciting in the TE mode of the low frequency band (20Gllz band) and the radiation pattern when exciting in the TE mode of the high frequency band (30GHz band). , and the radiation pattern when excited in multiple modes of the above-mentioned frequencies in the high frequency band are also shown. As can be seen from FIG. 3, regarding the main polarization radiation pattern, the high frequency radiation pattern is sharper than the low frequency radiation pattern.

Also, regarding the cross-polarized high frequency radiation pattern,
It can be seen that the level of the radiation pattern is sufficiently smaller in the case of excitation in multiple modes than in the case of excitation in TE mode.

In the reflector antenna using the primary horn 2 configured as described above, the edge direction of the reflector 1 is set, for example, in the third direction.
As shown in the figure, the edge level in the low frequency band is approximately -10 dB, and the edge level in the high frequency band is approximately -2 dB.
0 dB, the irradiation area of the reflector 1 in the high frequency band can be made small, and the beam width of the secondary radiation pattern emitted from the reflector 1 can be reduced between the low frequency band and the high frequency band. They can be made almost equal. Furthermore, since the high frequency band is excited in multiple modes, it is possible to reduce the cross-polarization level within the area illuminated by the reflector 1, and also to reduce the cross-polarization level in the secondary radiation pattern. can do.

Therefore, in such a reflector antenna, the beam widths of the radiation patterns in the low frequency band and the high frequency band can be made almost equal, and the radiation pattern in the high frequency band can be made rotationally symmetrical and cross-polarized. The wave level can be low.

Note that although the above embodiment describes the case where a tapered waveguide and a circular waveguide are used as structures for generating higher-order modes, the same effect can be obtained even if higher-order modes are generated using an iris, a group, etc. can be obtained. In addition, although we have explained the case where a single conical multi-mode horn is used as the primary horn, the same effect can be obtained by using a multi-mode horn such as a pyramidal horn or by using a plurality of these horns. . Furthermore, similar effects can be obtained by using a modified mirror surface as the reflecting mirror.

〔Effect of the invention〕

As described above, according to the present invention, a power feeding port for feeding power, a first waveguide connected to the power feeding port, a second waveguide connected to the first waveguide, a primary horn consisting of a horn section connected to the second waveguide;
The inner diameter of the waveguide was configured so that only fundamental mode radio waves propagated in the low frequency band, and in addition to the fundamental mode, higher mode radio waves also propagated in the high frequency band. It is possible to realize a radiation pattern with almost equal beam width in the low frequency band and high frequency band, and
The effect is that it is possible to realize a radiation pattern that is rotationally symmetrical in a high frequency band and has a low cross-polarization level.

[Brief explanation of the drawing]

FIG. 1(a) is a side view of a reflector antenna according to an embodiment of the present invention, FIG. 1(b) is a front view of the reflector antenna, and FIG. 2(a) is a reflector of this embodiment. A side view of the primary horn provided in the antenna, Fig. 2 (bl is a front view of the primary horn, Fig. 3 is a radiation pattern diagram of the primary horn, Fig. 4 (al is a side view of a conventional reflector antenna, FIG. 4(b) is a front view of the conventional reflector antenna. l... Reflector, 2... Primary horn, 3° 3a, 3b
...Power supply port, 4...Taber waveguide (first waveguide),
5... Circular waveguide (second waveguide), 6... Horn section. Agent Masuo Oiwa (2 idiots) Figure 3 Figure 4 (a) (b) Procedural amendment (voluntary) 3. Representative of the person making the amendment Moriya Shiki 5 Column for drawings to be amended. (i. Contents of amendment (11 drawings, Figure 4 (b) are amended as shown in the attached sheet.)

Claims (1)

[Claims] The above-mentioned reflector antenna includes a reflector that reflects radio waves and a primary horn that transmits and receives radio waves by irradiating the reflector, and transmits and receives radio waves in two frequency bands, a low frequency band and a high frequency band. The primary horn includes a power supply port for supplying power, a first waveguide connected to the power supply port, a second waveguide connected to the first waveguide, and a second waveguide connected to the second waveguide. The inner diameter of the second waveguide is such that only the fundamental mode radio waves propagate in the low frequency band, and that the fundamental mode radio waves propagate in the high frequency band. A reflector antenna characterized in that its dimensions are set so that radio waves of higher order modes are also propagated.