RU2664753C1 - Multi-focus offset mirror antenna - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: invention is intended for use as part of radio engineering devices of television, radio broadcasting and radio communication through artificial satellites of the Earth in the geostationary orbit, in the decimeter, centimeter and millimeter wave bands. Antenna consists of a system of irradiators operating in different frequency ranges and a mirror (reflector). In this case, the reflector itself consists of several layers in the form of asymmetrical cuttings from paraboloid rotation, vertices and focal axes of which coincide, but the focal lengths of the paraboloids are different and the phase center of one of the irradiators of the system is located at the focus of each layer. Layer with the largest focal length is a well conducting surface, the remaining layers are frequency-selective surfaces, which with minimal loss pass electromagnetic waves of layers with a large focal length and reflect waves of other ranges.

EFFECT: reduction of electromagnetic losses in the antenna due to the elimination of devices for dividing the frequency bands while maintaining the directional characteristics.

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Description

The invention is intended for use in the composition of radio engineering devices for television, broadcasting and radio communications through artificial Earth satellites (AES) in geostationary orbit (GSO) in the decimeter, centimeter and millimeter wave ranges.

Mirror antennas are known [1], consisting of a mirror (reflector) in the form of a conductive surface having the form of an axisymmetric or asymmetric notch from a rotation paraboloid, and an irradiator in the form of a weakly directed antenna at the focus of a rotation paraboloid. The range properties of such an antenna are determined by the irradiator. To receive / transmit radio waves simultaneously in several frequency ranges, multi-band irradiators with frequency range separation devices [2] are used, which are large in size and have a low efficiency.

Hybrid mirror antennas [1] are known, consisting of a reflector and a system (cluster) of irradiators, and mirror antennas with additional irradiators [3], in which, in addition to the main irradiator located at the focus of the mirror, there are additional irradiators offset from the focus. Such a shift of the irradiators, as is known [1], leads to the appearance of phase errors in the aperture of the antenna: a distortion of its radiation pattern, an increase in the level of side lobes, and a decrease in the gain.

Known combined designs of mirror antennas [2], containing the main mirror (reflector), two or more irradiators operating in different frequency ranges, and one or more auxiliary mirrors (counterreflectors) in the form of frequency-selective surfaces that transmit radio waves without loss to one frequencies and almost completely reflect on others. At one frequency, such antennas work according to a scheme with one reflector, at other frequencies - according to a scheme with a reflector and counter-reflector. The presence of counterreflectors in such antennas significantly increases their overall size.

The technical result of the invention is to reduce losses in the antenna by eliminating the device for the separation of frequency ranges while maintaining the directivity.

For this, a multi-focus offset SLR antenna is offered. It consists of a system of irradiators operating in different frequency ranges, and a mirror (reflector). In this case, the reflector itself consists of several layers in the form of asymmetric notches from rotation paraboloids, the vertices and focal axes of which coincide, but the focal lengths of the paraboloids are different and the phase center of one of the system irradiators is located at the focus of each layer. The layer with the largest focal length is a well-conducting surface, the remaining layers are frequency-selective surfaces that pass electromagnetic waves with minimal losses for layers with a large focal length and reflect electromagnetic waves of other ranges.

The invention is illustrated by the drawing of FIG. 1, which shows a cross section of a multifocal offset mirror antenna with three layers of a plane containing the focal axis of the paraboloids.

The multifocal offset mirror antenna (Fig. 1) contains a system of irradiators 1, 2 and 3 located on a common focal axis 4 of paraboloids of revolution with a common vertex 5, as well as a reflector consisting of layers 6, 7 and 8. Phase centers of irradiators operating on different frequencies, combined with the foci of paraboloids, which are located at different focal lengths relative to the vertex 5. The surfaces of the layers of the reflector 6, 7 and 8 are asymmetric notches from the corresponding paraboloids of revolution. In this case, the reflector layer 6 corresponding to the paraboloid with the greatest focal length is made of conductive material. The reflector layer 7 is made of frequency-selective materials that transmit electromagnetic waves with minimal losses with the frequency of the irradiator 1 installed at the focus of the layer 6, and almost completely reflect the electromagnetic waves of the remaining irradiators. The reflector layer 8, corresponding to the paraboloid with the smallest focal length, is made of frequency-selective material, which with minimal losses transmits electromagnetic waves with a frequency of all irradiators, except for irradiator 3 installed in the focus of layer 8, and reflects electromagnetic waves of irradiator 3.

The principle of operation of a multifocus offset mirror antenna in the approximation of geometric optics is illustrated by rays 9, 10 and 11. Due to the properties of the reflector layers described above, rays 9 emanating from the irradiator 1 will pass through layers 8, 7 with almost no attenuation and distortion and then reflect from the layer 6. Since the phase center of the irradiator 2 is aligned with the focus of the paraboloid describing the surface of the layer 6, after reflection, the beam 9 will be parallel to the focal axis 4. The rays 10 emanating from the irradiator 2, the phase center of which is aligned with the focus of the vapor the oloid describing the surface of layer 7, practically without attenuation and curvature, will pass through layer 8 and, reflected from layer 7, will be parallel to the focal axis 4. Rays 11 emanating from irradiator 3, the phase center of which is aligned with the focus of the paraboloid describing the surface of layer 8, will be reflected from this layer and will also become parallel to the focal axis 4. The rays reflected by the reflectors 6, 7, and 8 form a highly directed antenna radiation in each of the frequency ranges.

Thus, with respect to each of the irradiators (and, accordingly, each operating frequency), the multifocus mirror offset antenna works similarly to the well-known offset mirror antenna. Moreover, since each irradiator is located in the focus of the corresponding paraboloid, phase errors in the aperture of the mirror and the corresponding deterioration in the directional properties of the antenna will not occur.

Since each frequency range in the multifocal offset mirror antenna corresponds to a separate feed, there is no need for a bulky frequency band separation device. In addition, it becomes possible to use irradiators of significantly different types, including nutrition.

The dimensions of the multifocal offset mirror antenna are determined by the paraboloid with the largest focal length and are practically independent of the number of layers.

Thus, in the proposed multifocal offset mirror antenna due to the exclusion of the device for separating frequency ranges, the losses in the antenna are reduced, and the directivity characteristics are kept the same.

Information sources

1. Somov A.M., Kabetov R.V. Designing antenna-feeder devices: a Textbook for universities. / Ed. professors A.M. Somova. - M .: Hotline-Telecom, 2015 .-- 500 p .: ill.

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

3. Multipath hybrid mirror antenna: Patent RU 2556466: IPC H01Q 05/00. / Somov A.M .; Application RU 2013141948 dated 09/13/2013; publ. 07/10/2015

Claims (1)

A multifocal offset mirror antenna, consisting of a system of irradiators of different frequency ranges, and a mirror (reflector), characterized in that the reflector consists of several reflective layers in the form of asymmetric notches of rotation paraboloids, the vertices and focal axes of which coincide, the focal lengths of the paraboloids are different, in the focus of each layer is one of the irradiators of the system, the layer with the largest focal length is a conductive surface, the other layers are passed through frequency-selective surfaces electromagnetic wave layers with a large focal distance and reflects all other electromagnetic waves.

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