BACKGROUND ART Known design of dual-mirror antenna consists of primary mirror with parabolic generator with off-center focal axis parallel to axis of symmetry of dual- mirror antenna ; auxiliary mirror with hyperbolic generator, whose first focus is aligned to axis of symmetry of dual-mirror antenna and second focus coincides with focus of primary minor's parabolic generator; and antenna feed with phase center coinciding with first focus of hyperbolic generator; parabolic and hyperbolic generators superimpose at their intersection; primary mirror with parabolic generator is made up of half of figure of revolution and secondary mirror with hyperbolic generator is of two halves of figure of revolution, generated by revolution of segments of their generators around axis of symmetry of dual-mirror antenna within the semicircle and coinciding in the point located on axis of symmetry of dual-mirror antenna, other extreme point of hyperbolic generator being. the point of its intersection with straight line connecting second focus of hyperbolic generator with primary mirror's edge (pat. USSR #1322399, cl. HO1Q 19/19,1987).

That antenna does not allow for noise reduction (when used as a receiving antenna). Moreover, it does not provide for increase of surface utilization factor, reduction of dimensions, increase of electromagnetic energy concentration degree by reflecting waves in parallel directions, nor by creating phase coincidence.

There is a known dual-mirror antenna with reduced absolute cross-section consisting of parabolic mirror, flat finned mirror and antenna feed radiating spherical electromagnetic waves with vertical polarization. Parabolic mirror consists of set of vertical metal plates fixed on paraboloid of revolution made of radioparent substance with X/8 distance between them, where X is the length of electromagnetic waves. Flat finned mirror consists of metal sheet with attached at 45'to vertical metal plates with 1/4 altitude and distance between them not exceeding \/8. Construction includes hemispherical mirror consisting of a set of horizontal metal plates fixed on a hemisphere made of radioparent substance at X/8 distance between them and attached above the antenna feed so that its center coincides with feed's phase center (pat. Russian Federation #2072597, cl. H 01 Q 19/195,1997).

Drawback of this construction is impossibility of noise level reduction, increase of surface utilization factor, reduction of dimensions, increase of electromagnetic energy concentration degree by reflecting waves in parallel directions, nor by creating phase coincidence.

Most similar to proposed invention is dual-mirror antenna consisting of primary parabolic mirror and sensor (antenna feed). Auxiliary parabolic mirror and antenna feed are installed coaxially with focal axis of primary parabolic mirror, while auxiliary mirror has an ability to be rotated up to 90° around focal axis and provided with rotation drive (pat. USSR #1543485, cl. H 01 Q 19/18, 1990).

This antenna also does not reduce noise level, and does not provide for increase of surface utilization factor, reduction of dimensions, increase of electromagnetic energy concentration degree by reflecting waves in parallel directions, nor by creating phase coincidence.

DISCLOSURE OF INVENTION Invention purpose is development of antenna design consisting of two parabolic mirrors for radiation, reception of electromagnetic waves and providing for direction-finding of radio objects, radiolocation and radionavigation purposes.

Technical goal of reduction of noise level of receiving antenna, increase of surface utilization factor, reduction of dimensions, increase of electromagnetic energy con concentration degree by reflecting waves in parallel directions and creating phase coincidence is achieved because in dual-mirrored antenna consisting of primary parabolic mirror, auxiliary parabolic mirror and sensor, according to the invention, focuses of primary parabolic mirror and auxiliary parabolic mirror coincide and parabolic generators of both mirrors are defined by following correlation: X2+ y2= (R-x) 2 x2 + y2= (r-x) 2, where R is the radius of generator of primary parabolic mirror ; r is the radius of generator of auxiliary parabolic mirror, x and y are datum lines.

Proposed antenna construction can be made in following variations.

Raster angles of primary parabolic mirror and auxiliary parabolic mirror are equal.

Convex surface of auxiliary parabolic mirror is directed towards concave surface of primary parabolic mirror.

Concave surface of auxiliary parabolic mirror is directed towards concave surface of primary parabolic mirror.

Sensor is installed between primary parabolic mirror and auxiliary parabolic mirror.

Sensor is installed at exterior of primary parabolic mirror, where an aperture for electromagnetic waves reflected by auxiliary parabolic mirror is made.

Sensor diameter is equal to auxiliary parabolic mirror diameter.

Coincidence of focuses of primary parabolic mirror and auxiliary parabolic mirror provides for reduction of receiving antenna noise level, eliminating influence of foreign radio objects, and reduces the device's dimensions.

Execution of parabolic generators of both mirrors according to correlation X2+ y2 = (R-X) 2IIX2 + y2 = (r-x) 2, where R and r are radii of primary parabolic mirror and auxiliary parabolic mirror respectively increases electromagnetic energy concentration degree by reflecting waves in parallel directions and creates phase coincidence of electromagnetic waves.

BRIEF DESCRIPTION OF DRAWINGS The invention is explained by the drawing where Fig. l snows the device schematics with convex surface of auxiliary parabolic mirror directed towards concave surface of primary parabolic mirror and sensor installed between primary parabolic mirror and auxiliary parabolic mirror; Fig. 2 shows the same schematics with sensor installed at exterior of primary parabolic mirror ; Fig. 3 shows the schematics with concave surface of auxiliary parabolic mirror directed towards concave surface of primary parabolic mirror and sensor installed between primary parabolic mirror and auxiliary parabolic mirror; and Fig. 4 shows the same schematics with sensor installed at exterior of primary parabolic mirror.

THE MODES FOR CARPING OUT THE INVENTION Dual-mirror antenna consists of primary parabolic mirror (1), auxiliary parabolic mirror (2) and sensor or antenna feed (3). Foci (4) of primary parabolic mirror (1) and auxiliary parabolic mirror (2) coincide and parabolic generators of both mirrors are defined by following correlation: X2+ y2= (R-x) 2 ; x2 + y2 = (r-x) 2, where R is the radius of generator of primary parabolic mirror; r is the radius of generator of auxiliary parabolic mirror; x and y are datum lines.

Raster (aperture) angles of primary parabolic mirror (1) and auxiliary parabolic mirror (2) are equal.

Convex surface of auxiliary parabolic mirror (2) is directed towards concave surface of primary parabolic mirror (1).

Concave surface of auxiliary parabolic mirror (2) is directed towards concave surface of primary parabolic mirror (1).

Sensor (3) is installed between primary parabolic mirror (1) and auxiliary parabolic mirror (2).

Sensor (3) is installed at exterior of primary parabolic mirror (1), where an aperture (5) for electromagnetic waves reflected by auxiliary parabolic mirror (2) is made Sensor (3) diameter is equal to auxiliary parabolic mirror (2) diameter.

Dual-mirror antenna works as follows.

When used as a receiving device, electromagnetic waves reflect from concave surface of primary parabolic mirror (1) to auxiliary parabolic mirror (2), that reflects hem as a parallel beam on sensor (3).

Sensor (3) serves as the radiation receiver.

INDUSTRIAL APPLICABILITY In manufacturing the dual-mirror antenna, metal, preferrably ferromagnetic, is used, for example, 1 mm thick tin plate. Surface of each mirror must be thoroughly polished to reduce surface granularity.

To protect metal against corrosion, coating containing ! orthophosphoric acid, paint that does not reflect the radiation, aluminium, etc is used.

Signal receivers are selected depending on frequency range and waveband of received electromagnetic radiation. For satellite reception, converter Eurostar ESKD-F8, Ku LNB with C-120 flange can be used, with following specifications: a. Input Freq. 10.7-11. 7-12.78GHz b. L. O. Freq. 9.75/10. 6GHz c. Bandsw. 0/22KHz Low/HighBand d. Output Freq. 950-2150MHz e. Polarity sw. Ver. 14V/Hor. 18V