RU2776723C1 - Axisymmetric multiband multimirror antenna - Google Patents

Abstract

FIELD: antenna technology.

SUBSTANCE: invention relates to antenna technology, in particular to antennas of earth stations of satellite communication systems with repeaters of the microwave-EHF bands. The effect is achieved by the fact that the axisymmetric antenna, consisting of three feeds, the main reflector with a generatrix in the form of a parabola, symmetrical about its focal axis, and an auxiliary counter-reflector, coaxial to the parabola, is characterized in that the counter-reflector has the shape of a parabola, concave away from the reflector, moreover, the focal axis of this parabola is both the axis of axial symmetry of the antenna and the axis of symmetry of the counter-reflector, and the feed of the first frequency range is installed in its focus, an axisymmetric secondary reflector with a cross section similar to the reflector section and a diameter equal to the diameter of the counter-reflector, as well as a secondary counter-reflector with a cross section in the form of an ellipse, the focal axis of which coincides with the axis of axial symmetry of the antenna, is installed coaxially on the focal axis of the reflector, in the focus of the ellipse, far from at the top of the secondary reflector and coinciding with its focus, the feed of the second frequency range is installed, and at the focus of the ellipse, closest to the top of the secondary reflector, the feed of the third frequency range is installed.

EFFECT: improving the efficiency of the antenna while simultaneously receiving radio waves of three frequency bands.

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Description

The technical field to which the invention belongs

At present, artificial Earth satellites (AES) are widely used for radio communications and digital broadcasting - repeaters located in geostationary orbit (GSO) and simultaneously using the C, Ku and Ka frequency bands. In the future, it is planned to use frequency bands of 40 GHz and more [1].

The present invention relates to the field of radio engineering and is intended for use as antennas for earth stations of satellite communication systems with repeaters of the microwave-EHF ranges located on the GSO, to operate simultaneously in three frequency bands.

State of the art

Known [2] multi-range two-mirror antennas, consisting of a main parabolic reflector mirror, an auxiliary mirror-counterreflector in the form of an ellipsoid or hyperboloid, coaxial to the reflector, and the irradiator at the focus of the counterreflector. Such antennas make it possible to organize radio communication via satellites on the GSO simultaneously in several frequency bands using frequency band separation devices [2, 3]. The disadvantages of such an antenna system include its reduced efficiency when receiving several bands at the same time on one feed due to the loss of electromagnetic energy in the frequency band separation device.

Two-mirror antennas of the Gregory type with two feeds are known, one of which is located at the focus of the main parabolic reflector, and the second at the focus of the elliptical counter-reflector, remote from the top of the parabolic reflector [4]. Each of these feeds receives its own frequency range from the same direction. Such antennas separately receive two different bands simultaneously without the use of a frequency band splitter.

Disclosure of the essence of the invention

The technical result of the invention is to increase the efficiency of the antenna while receiving three frequency bands simultaneously by eliminating the frequency separation device, which introduces additional losses in the reception path. For this, an axisymmetric multi-band multi-mirror antenna is proposed, consisting of three feeds, a main reflector with a generatrix in the form of a parabola, symmetrical about its focal axis, and an auxiliary counter-reflector mirror coaxial to the parabola. In this case, the counter-reflector has the shape of a parabola, concave away from the reflector. The focal axis of this parabola is the axis of axial symmetry of the antenna and at the same time the axis of symmetry of the counter-reflector, and the feed of the first frequency range is installed at its focus. An axisymmetric secondary reflector with a cross section similar to that of the reflector and a diameter equal to the diameter of the counter-reflector, as well as a secondary counter-reflector with a cross section in the form of an ellipse, the focal axis of which coincides with the axis of axial symmetry of the antenna, is installed coaxially on the focal axis of the reflector. An irradiator of the second frequency range is installed at the focus of the ellipse, far from the top of the secondary reflector and coinciding with its focus, and an irradiator of the third frequency range is installed at the focus of the ellipse, closest to the top of the secondary reflector.

Brief description of the drawings

The invention is illustrated by a drawing (Fig. 1), which indicates:

1 - main mirror (reflector);

2 - counter-reflector;

3 - irradiator of the first frequency range;

4 - secondary reflector;

5 - secondary counter-reflector;

6 - irradiator of the second frequency range;

7 - irradiator of the third frequency range;

8 - axis of axial symmetry of the antenna;

9 - the direction of the rays of the irradiator 3 to the edges of the reflector 1;

10 - the direction of radiation of the antenna, formed by feeds 3, 6 and 7;

11 - the direction of the rays of the irradiator 6 to the edges of the secondary reflector 4;

12 - the direction of the rays from the secondary reflector 4 to the counter-reflector 2;

13 - the direction of the beams of the irradiators 6 and 7 to the edges of the reflector 1;

14 - the direction of the rays of the irradiator 7 from the secondary counter-reflector 5 to the secondary reflector 4.

Implementation of the invention

An axisymmetric multi-range multi-mirror antenna (Fig. 1) consists of a main reflector 1 and a counter-reflector 2 in the form of paraboloids of revolution with coinciding focal axes and foci forming parabolas, but facing in opposite directions. In the common focus of parabolas 1 and 2, the irradiator 3 is placed.

When a high-frequency generator of the first frequency range is connected to the irradiator 3, the irradiator 3 radiates the field of the first frequency range towards the reflector 1. Since the reflector is usually located in the far radiation zone relative to the irradiator, this wave can be considered in the form of rays 9. Since the surface of the reflector 1 is a paraboloid , and the irradiator is in its focus, these rays after reflection form in the aperture of the reflector in-phase electromagnetic field, which corresponds to the radiation pattern with a maximum of radiation and, accordingly, reception from the direction of the focal axis, coinciding with the direction of the axis of axial symmetry of the antenna 8.

When a high-frequency generator of the second frequency range is connected to the irradiator 6 located at the focus of the secondary reflector 4, an in-phase field is also formed in its opening, which forms a plane wave in the far zone. This wave propagates along the focal axis and hits the inner surface of the counter-reflector 2, after reflection from which, passing through the focus of the reflector 1, which coincides with the position of the focus of the counter-reflector 2, excites the reflector 1 at the frequency of the generator of the second frequency range. In the opening of the reflector 1, an in-phase field of the second frequency range is formed with a maximum of radiation and, accordingly, reception from the same direction of the axial symmetry axis 8.

When connected to the irradiator 7, located at a focus remote from the secondary counter-reflector 5, a high-frequency generator of the third frequency range, a spherical wave of this range hits the inner surface 5. After reflection from it, including in the form of rays 14, after crossing the focus of the secondary counterreflector 5, coinciding in position with the focus of the secondary reflector 4, the field of the third frequency range falls on the inner surface of the secondary reflector. According to the properties of the Gregory antenna formed by the irradiator 7 and the surfaces of the secondary counter-reflector 5 and the secondary reflector 4, a plane wave of the third frequency range is formed in its aperture. This wave propagates in the direction of the axial axis of symmetry of the antenna and hits the inner surface of the counter-reflector 2. After reflection from it, passing through the focus of the reflector 1, which coincides with the position of the focus of the counter-reflector 2, the specified wave excites the reflector 1 at the frequency of the generator of the third frequency range. Due to this, in the opening of the reflector 1, an in-phase field of the third frequency range is formed with a maximum of radiation, and, accordingly, of reception, from the same direction of the axial symmetry axis of the antenna 8.

Irradiators 3, 6 and 7 have a shading effect on each other's radiation. At the same time, according to the geometric constructions of the beam path, the shading effect of the irradiator 7, which it has on the radiation of the irradiator 6, does not exceed the shading from the secondary counter-reflector 5. The shading effect of the irradiators 3 and 6 can be minimized with an appropriate distribution of frequency ranges over the irradiators. If the first band corresponds to the highest frequencies (for example, Ka band), the second band - to medium frequencies (Ku band), the third band - to low frequencies (C band), then the dimensions of the irradiator 3 will be much smaller than the wavelengths relative to the second and third bands, and the dimensions of the irradiator 6 are much smaller than the wavelength of the third range. In this case, the impact of the irradiators 3 and 6 on the electromagnetic waves passing by them will be small.

For simultaneous operation in several frequency ranges, known antennas use feeds that are common to several frequency ranges in conjunction with band separation devices that introduce additional high-frequency losses, reduce the utilization factor and increase the noise temperature of the antenna. In the proposed antenna, the separation of frequency bands is carried out by the method of spatial division of the reception into several feeds 3, 6 and 7, which increases the efficiency of the antenna.

Sources of information

1. Spodobaev M.Yu. Key challenges and main trends in the development of the satellite communications industry in the medium term / SATCOMRUS 2017, November 1, 2017

2. Frolov O.P., Wald V.P. Mirror antennas for satellite earth stations. - M.: Hotline-Telecom, 2008. - 496 p.: ill.

Fig. 3. Cascade of a microwave receiver with frequency separation of orthogonal polarizations of two frequency ranges: Patent RU 2136088: IPC H01R 1/161, H04V 1/00 / A.M. Somov, A.V. Pugachev. Application RU 98105930 dated March 17, 1998, publ. 08/27/1999

4. Multibeam combined reflector antenna. Patent RU 2627284: IPC H01Q 5/00 / A.M. Somov. Application RU 2016127926 dated July 12, 2016, publ. 08/04/2017

Claims (1)

An axisymmetric multi-range multi-mirror antenna, consisting of three feeds, a main reflector with a generatrix in the form of a parabola, symmetrical about its focal axis, and an auxiliary mirror-counter-reflector, coaxial to the parabola, characterized in that the counter-reflector has the shape of a parabola, concave away from the reflector, moreover, the focal axis of this parabola is the axis of axial symmetry of the antenna and at the same time the axis of symmetry of the counter-reflector, and the feed of the first frequency range is installed in its focus, an axisymmetric secondary reflector with a cross section similar to the reflector section and a diameter equal to the diameter of the counter-reflector is installed coaxially on the focal axis of the reflector, as well as a secondary counter-reflector with a cross section in the form of an ellipse, the focal axis of which coincides with the axis of axial symmetry of the antenna; it to the top of the secondary reflector, the irradiator of the third frequency range is installed.

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