RU2776722C1 - Axisymmetric multi-band multi-beam multi-reflector antenna - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: 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 bands located in geostationary orbit, for simultaneous operation with several artificial Earth satellites, each of which operates simultaneously in three frequency bands. The substance of the claimed solution lies in the fact that an axisymmetric multi-band multi-beam multi-mirror antenna, consisting of a main reflector mirror with a generatrix in the form of a parabola, symmetrical about its focal axis, an auxiliary counter-reflector mirror, coaxial to the parabola, and irradiators. 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 in the plane passing through the focus orthogonally to the focal axis, feeders of the first frequency range are installed. An axisymmetric secondary reflector with a cross section similar to that of the reflector and 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, are installed coaxially on the focal axis of the reflector. In the plane passing orthogonally to the specified axis through the focus of the ellipse, which is farthest from the top of the secondary reflector and coinciding with its focus, feeders of the second frequency range are installed, and in the plane passing orthogonally to the specified axis through the focus of the ellipse, which is closest to the top of the secondary reflector, feeders of the third range are installed frequencies.

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 earth station antennas of satellite communication systems with repeaters of the microwave-EHF ranges located on the GSO for simultaneous operation with several communication satellites, each of which operates 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.

Also known is a multibeam combined two-mirror antenna [4], consisting of an axisymmetric main reflector mirror having the shape of a paraboloid, and an auxiliary mirror-counterreflector in the form of an ellipsoid, coaxial with the paraboloid and concave away from the reflector. The irradiators of the first frequency range are located in a plane orthogonal to the focal axis and passing through the focus of the counterreflector close to the reflector. The irradiators of the second range are installed in a plane orthogonal to the focal axis and passing through the focus of the counter-reflector remote from the reflector. Such an antenna can simultaneously receive two different frequency ranges from satellites from each direction.

Disclosure of the essence of the invention

The technical result of the invention is to increase the efficiency of the antenna while maintaining the direction of the multipath radiation patterns and simultaneously receiving three frequency bands from each direction. For this, an axisymmetric multi-band multi-beam multi-mirror antenna is proposed, consisting of a main reflector mirror with a generatrix in the form of a parabola, symmetrical about its focal axis, an auxiliary counter-reflector mirror, coaxial to the parabola, and irradiators. 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 in the plane passing through the focus orthogonally to the focal axis, feeders of the first frequency range are installed. An axisymmetric secondary reflector with a cross section similar to that of the reflector and 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, are installed coaxially on the focal axis of the reflector. In the plane passing orthogonally to the specified axis through the focus of the ellipse, which is farthest from the top of the secondary reflector and coinciding with its focus, feeders of the second frequency range are installed, and in the plane passing orthogonally to the specified axis through the focus of the ellipse, which is closest to the top of the secondary reflector, feeders of the third range are installed frequencies.

Brief description of the drawings

The invention is illustrated by drawings, in which:

- fig. 1 - section of an axisymmetric multi-band multi-beam multi-mirror antenna by a plane containing the axis of axial symmetry;

- fig. 2 - axisymmetric multi-band multi-beam multi-mirror antenna, view from the side of the counter-reflector.

The drawings indicate:

1 - reflector;

2 - counter-reflector;

3 - irradiators of the first frequency range;

4 - secondary reflector;

5 - secondary counter-reflector;

6 - irradiators of the second frequency range;

7 - irradiators of the third frequency range;

8 - focal axis of parabolas 1, 4 and ellipse 5;

9 - rays from the edges of the reflector 2 and irradiator 3 to the edges of the reflector 1;

10 - direction of radiation of the antenna from the central feeds 3, 6 and 7;

11 - the direction of the rays from the irradiators 7 and 6 from the foci 4 and 5 to the edges 4;

12 - direction of propagation of a plane wave from the secondary reflector 4 for the fields of the central feeds 6 and 7;

13 - rays from the central irradiators 3, 6 and 7 to the edges of the reflector 1;

14 - a line similar to the segments of the GSO connecting the points of standing of the satellite.

Implementation of the invention

An axisymmetric multi-band multi-mirror antenna (Fig. 1) with a 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 different directions, contains a feed 3 in the common focus of parabolas 1 and 2.

When a high-frequency generator of the first frequency range is connected to the irradiator 3, the irradiator emits a spherical wave, including towards the upper and lower edges of 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. After reflection From the reflector 1, these rays, since they come from the focus of the parabola, form in the transmission mode an in-phase field in the antenna opening and directional radiation 10 along the focal axis 8. According to the principle of reciprocity, the same reverse processes occur in the reception mode.

A secondary reflector 4 in the form of a paraboloid of revolution and a secondary counter-reflector 5 in the form of an ellipsoid of revolution are installed on the axis of the reflector 1, coaxially with it. In the farthest focus of the secondary counter-reflector 5 relative to the top 4, which is a common focus for both the secondary paraboloidal reflector 4 and the ellipsoidal secondary counter-reflector 5, an irradiator 6 is installed. When a generator of the second frequency range is connected to the irradiator 6, an in-phase field is also formed in the opening 4. This in-phase field of the second frequency range in the form of a flat front falls into the opening of the counter-reflector 2 and, due to the properties of the parabola, is reflected by the counter-reflector 2 into its focus, propagates after it passes further to the opening of the reflector 1. Due to the properties of the parabola that forms the reflector 1, in the opening of the reflector 1 an in-phase field of the second frequency range arises, forming a directional emission (and reception) of this frequency range, coinciding with the direction of emission and reception of the first frequency range.

When the generator of the third frequency range is connected to the irradiator 7, located in the focus of the secondary counter-reflector 5 closest to the top 4, the field of the irradiator 7 hits the upper and lower edges and other points of the surface of the secondary counter-reflector 5, is reflected on the lower, upper edge and other points of the working surface of the secondary reflector 4, passing through the focus of the secondary counter-reflector 5, common with the focus of the secondary reflector 4. The plane wave front from the irradiator 7, the secondary reflector 4 and the counter-reflector 5, forming the well-known Gregory system, falls on the counter-reflector 2, after reflection by which and passing through its focus and the focus of reflector 1 falls into the aperture of reflector 1. Due to the properties of the parabola that forms reflector 1, the field of the third frequency range, after reflection by reflector 1, forms directional radiation (and reception) along the focal axis of reflector 1.

Next to the feeds on the axis of axial symmetry of the antenna of the first 3, second 6 and third 7 frequency ranges can be placed in planes orthogonal to the focal axis of the reflector 1, three additional feeds of the same frequency ranges. These triple feeds are located at the points of the broken line 14 connecting the standing points of the satellites of the GSO cluster to receive the corresponding frequencies. The multibeam radiation pattern (DN) is formed by three irradiators 3, 6 and 7 when generators of corresponding frequencies are connected to them. According to the reciprocity theorem, a similar triplet of the antenna pattern is also formed for three frequency ranges and in the antenna reception mode.

Any of the irradiators 3, displaced in a plane orthogonal to the focal axis 8, from the focus of the counter-reflector 2 along line 14, similar to the curve describing the GSO line, is also a source of primary electromagnetic waves. In the approximation of geometric optics, the rays emanating from the irradiators 3, after successive reflections from the reflector 1, due to the properties of a second-order curve of the parabola type and the displacement of the irradiators from the focal axis of the antenna 8, form a fan of partial antenna patterns. A similar fan of DN is formed from the offset feeds 6 of the second frequency range and from the offset feeds 7 of the third frequency range. The displacement of the irradiators is determined by the angular displacement of the placement point of the serviced satellite on the GSO relative to the placement point of the virtual satellite on the GSO in the direction of the axis of the partial RP formed by the feed located at the focus of the paraboloid.

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 reception into several feeds 3, 6 and 7. The displacement of the feeds in a plane orthogonal to the focal axis of the parabola is advisable when servicing a narrow sector of GSO angles, and the absence of a frequency separation device makes it possible to implement a high antenna gain at low noise temperature. This achieves an increase in the efficiency of the antenna.

LITERATURE

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; Published 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; Published 08/04/2017

Claims (1)

An axisymmetric multi-band multi-beam multi-mirror antenna, consisting of a main reflector with a generatrix in the form of a parabola, symmetrical about its focal axis, an auxiliary mirror-counter-reflector, coaxial to the parabola, and irradiators, 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 in the plane passing through the focus orthogonally to the focal axis, feeders of the first frequency range are installed, on the focal axis of the reflector, axisymmetric secondary reflectors with a cross section similar to the reflector section are installed coaxially with it, and a secondary counter-reflector with a section in the form of an ellipse, the focal axis of which coincides with the axis of axial symmetry of the antenna, in a plane passing orthogonally to the specified axis through the focus of the ellipse, which is far from the top of the secondary reflector and coincides with its focus, set irradiators of the second frequency range are located, and in the plane passing orthogonally to the indicated axis through the focus of the ellipse, closest to the top of the secondary reflector, irradiators of the third frequency range are installed.

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