RU2807497C1 - Axisymmetric multi-band multi-beam multi-mirror antenna - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: invention and serves as antennas for earth stations of satellite communication systems with microwave-EHF repeaters located in geostationary orbit for simultaneous operation with several artificial Earth satellites, each of which operates simultaneously in three frequency ranges. The technical result is to increase the efficiency of the antenna while simultaneously receiving radio waves of three frequency ranges. The result is achieved by proposing an axisymmetric multi-band multi-beam multi-mirror antenna, consisting of three clusters of feeds of different frequency ranges, a main reflector in the form of an axisymmetric cut-out from a paraboloid of rotation, the focal axis of which is the axis of axial symmetry of the antenna, and an auxiliary counter-reflector in the form of an axisymmetric convex towards the reflector cuttings from a hyperboloid of revolution, the focal axis and the farthest focus relative to the reflector coincide, respectively, with the focal axis and focus of the reflector, as well as the axisymmetric secondary reflector and secondary counter-reflector with sections in the form of ellipses installed on the focal axis of the reflector coaxially.

EFFECT: increased efficiency of the antenna while simultaneously receiving radio waves of three frequency ranges.

1 cl, 2 dwg

Description

Field of technology to which the invention relates

Currently, 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 ranges 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 microwave-HF range repeaters located in the GSO, for simultaneous operation with several communication satellites, each of which operates simultaneously in three frequency ranges.

State of the art

Known [2] are multi-band dual-mirror antennas, consisting of a main parabolic reflector mirror, an auxiliary counter-reflector mirror in the form of an ellipsoid or hyperboloid, coaxial to the reflector, and an irradiator at the focus of the counter-reflector. Such antennas make it possible to organize radio communications through satellites on the GSO simultaneously in several frequency ranges using devices for separating frequency ranges [2, 3]. The disadvantages of such an antenna system include its reduced efficiency when simultaneously receiving several bands on one feed due to losses of electromagnetic energy in the device for separating frequency ranges.

Two-mirror Gregory-type antennas 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 a different range of frequencies from the same direction. Such antennas separately receive two different bands simultaneously without the use of a frequency band separation device.

An axisymmetric multi-band multi-beam multi-mirror antenna is also known [5], which simultaneously receives three frequency ranges from several directions. It consists of a main reflecting mirror with a generatrix in the form of a parabola, an auxiliary counter-reflecting mirror coaxial to the parabola, and irradiators. In this case, the counter-reflector has the shape of a parabola, concave away from the reflector. On the focal axis of the reflector, coaxially with it, there 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.

Disclosure of the invention

The technical result of the proposed invention is to increase the efficiency of the antenna while simultaneously receiving three frequency ranges by eliminating the frequency separation device, which introduces additional losses into the reception path. For this purpose, an axisymmetric multi-band multi-beam multi-mirror antenna is proposed, consisting of three clusters of feeds of different frequency ranges, a reflector - the main mirror in the form of an axisymmetric cutout from a paraboloid of revolution, the focal axis of which is the axis of axial symmetry of the antenna, and a counter-reflector - an auxiliary mirror in the form of a convex mirror towards the reflector an axisymmetric cut from a hyperboloid of revolution, the focal axis and the focus farthest relative to the reflector coincide, respectively, with the focal axis and focus of the reflector. On the focal axis of the reflector, an axisymmetric secondary reflector and a secondary counter-reflector are installed coaxially with sections in the form of ellipses, the focal axes of which coincide with the axis of axial symmetry of the antenna, and the far focus of the secondary reflector coincides with the focus of the counter-reflector closest to the reflector, and the near focus of the secondary reflector coincides with the near one focus of the secondary counter-reflector. Feed clusters are installed in planes orthogonal to the axial symmetry axis of the antenna: in the plane passing through the focus of the counter-reflector, closest to the reflector, - a cluster of feeds of the first frequency range, facing the counter-reflector, in a plane passing through the near focus of the secondary counter-reflector, - a cluster of feeds of the second range frequencies facing the secondary reflector, in a plane passing through the far focus of the secondary counter-reflector, is a cluster of feeds of the third frequency range.

Brief description of drawings

The invention is illustrated by drawings, in which:

- fig. 1 - longitudinal section of an axisymmetric multi-band multi-beam multi-mirror antenna;

- fig. 2 - projection of the elements of an axisymmetric multi-band multi-beam multi-mirror antenna onto the plane of its opening.

The drawings indicate:

1 - main reflector mirror;

2 - counter-reflector;

3 - cluster of irradiators of the first frequency range;

4 - secondary reflector;

5 - secondary counter-reflector;

6 - cluster of irradiators of the second frequency range;

7 - cluster of irradiators of the third frequency range;

8 - axis of axial symmetry of the antenna;

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

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

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

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

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

14 - direction of the rays of the cluster of irradiators 7 to the edges of the secondary counter-reflector 5;

15 - line similar to the GSO curve from clusters of range irradiators in the direction of the satellite.

Carrying out the invention

When connected to one of the feeds of cluster 3, designed to receive a given satellite, a high-frequency generator of the first frequency range, this feed emits an electromagnetic wave towards the counter-reflector 2 (Fig. 1). Since this counter-reflector is located in the far zone of the feed, the specified wave is spherical, and the feed-counter-reflector-reflector system works like the well-known Cassegrain antenna [2]. In this case, for the irradiator located in the first focus of the hyperboloid, rays 12 emitted towards the edges of the counter-reflector 2, after reflection from it, are transformed into rays 9, as if emanating from the second (imaginary) focus of the said hyperboloid. After reflection from the reflector 1 in the antenna aperture, an in-phase wave front and directed radiation 10 along the focal axis 8 are formed. According to the principle of reciprocity, reverse processes also occur in the receiving mode, providing communication with the assigned satellite in the first frequency range. Similar processes occur when other feeds from cluster 3 are connected at small displacements from the focal axis, providing service to other satellites in the first frequency range.

On the axis of the reflector 1, a secondary reflector 4 in the form of an ellipsoid of rotation and a secondary counter-reflector 5, also in the form of an ellipsoid of rotation, are installed coaxially with it. At the farthest focus of the secondary counter-reflector 5 relative to the top of the secondary reflector 4, a cluster of feeds 6 is installed. When a second frequency range generator is connected to the feed from cluster 6, this feed emits an electromagnetic wave towards the secondary reflector 4. Taking into account the placement of the feed in the far zone, this wave is spherical. In this case, the rays 11 emitted towards the edges of the secondary reflector 4 by the irradiator located on the focal axis 8, that is, at the focus of the ellipsoid, after reflection in the form of rays 13, will pass through the second focus of the secondary reflector 4, coinciding with the focus of the counter-reflector 2. Further path of the rays will be similar to the ray path for the feed from cluster 3 for the first frequency range. Thus, for the second frequency range, an in-phase wave front and directed radiation 10 along the focal axis 8 are also formed in the aperture of the reflector 1. Similar processes occur with a slight displacement of the feed, providing service to other satellites in the second frequency range.

When a high-frequency generator of the third frequency range is connected to the cluster irradiator 7, located at a focus distant from the secondary reflector 5, a spherical wave falls from it onto the inner surface 5. After reflection from it, including in the form of rays 14, after crossing at the focus secondary counter-reflector 5, which coincides 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 4 in the form of rays similar to rays 11 of the second frequency range. Taking this into account, the further passage of the wave of the third frequency range is similar to the wave of the second frequency range. Thus, for the third frequency range, an in-phase wave front and directed radiation 10 along the focal axis 8 are formed in the aperture of the reflector 1.

Irradiators of clusters 3, 6 and 7 can be placed on curve 15, similar to the curve describing the GSO line (Fig. 2). In the geometric optics approximation, the rays emanating from the feeds of cluster 3, after successive reflections from the reflector 1, due to the properties of the second-order parabola-type curve and the displacement of the feeds from the focal axis of the antenna 8, form a fan of partial radiation patterns (DP) of the antenna. A similar pattern fan is formed from offset feeds of cluster 6 of the second frequency range and from offset feeds of cluster 7 of the third frequency range. The displacement of the feeds is determined by the angular displacement of the point of placement of the serviced satellite on the GEO relative to the point of placement of the virtual satellite on the GSO in the direction of the axis of the partial pattern formed by the feed located at the focus of the paraboloid.

The irradiators of clusters 3, 6 and 7 have a shadowing effect on each other’s radiation. According to the geometric constructions of the ray path, the shadowing effect of the cluster 7 feed, which it has on the radiation of the cluster 6 feed, does not exceed the shadowing from the secondary counter-reflector 5. The shadowing effect of the cluster feeds 3 and 6 can be minimized with an appropriate distribution of frequency ranges among the feeds. If the first range corresponds to the highest frequencies (for example, Ka range), the second range - to medium frequencies (Ku range), the third range - to low frequencies (C range), then the dimensions of the cluster 3 feed will be much smaller than the wavelengths relative to the second and third ranges, and the dimensions of the cluster 6 feed are much smaller than the wavelength of the third range. In this case, the impact of the irradiators of clusters 3 and 6 on the electromagnetic waves passing by them will be small.

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

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 realize a high antenna gain at a low noise temperature. In addition, the antenna has the ability to change the ratio of the structural dimensions of the secondary reflector and counter-reflector, which is important when it is placed and operated in cramped operating conditions. This achieves increased antenna efficiency.

LITERATURE

1. Sdobaev 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.

3. Cascade of a microwave receiving device with frequency separation of orthogonal polarizations of two frequency ranges: Patent RU 2136088: MPK N01R1/161, N04 B1/00. / 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 H01Q5/00. / A.M. Somov; Application RU 2016127926 dated 07/12/2016; Publ. 08/04/2017.

5. Axisymmetric multi-band multi-beam multi-mirror antenna: Patent RU 2776722: IPC H01Q3/30. / Applicant and patent holder Academy of the FSB of Russia; Application 2021119064 dated 06/29/2022; Publ. 07/26/2022.

Claims (1)

An axisymmetric multi-band multi-beam multi-mirror antenna consisting of three clusters of feeds of different frequency ranges, a reflector - the main mirror in the form of an axisymmetric cutout from a paraboloid of rotation, the focal axis of which is the axis of axial symmetry of the antenna, and a counter-reflector - an auxiliary mirror in the form of an axisymmetric cutout convex towards the reflector hyperboloid of rotation, the focal axis and the farthest focus relative to the reflector coincide, respectively, with the focal axis and the focus of the reflector, characterized in that on the focal axis of the reflector, coaxially with it, an axisymmetric secondary reflector and a secondary counter-reflector are installed with sections in the form of ellipses, the focal axes of which coincide with the axial axis symmetry of the antenna, and the far focus of the secondary reflector coincides with the focus of the counter-reflector closest to the reflector, and the near focus of the secondary reflector coincides with the near focus of the secondary counter-reflector, clusters of feeds are installed in planes orthogonal to the axis of axial symmetry of the antenna: in the plane passing through the focus of the counter-reflector, closest to reflector, - a cluster of irradiators of the first frequency range, facing the counter-reflector, in a plane passing through the near focus of the secondary counter-reflector, - a cluster of irradiators of the second frequency range, facing the secondary reflector, in a plane passing through the far focus of the secondary counter-reflector, - a cluster of irradiators of the third range frequency

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