Cassegrain Antenna


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Cassegrain antenna

[kas·gran an′ten·ə]
(electromagnetism)
A microwave antenna in which the feed radiator is mounted at or near the surface of the main reflector and aimed at a mirror at the focus; energy from the feed first illuminates the mirror, then spreads outward to illuminate the main reflector.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Cassegrain Antenna

 

(named for the 17th-century French physicist N. Cassegrain), a reflecting antenna that consists of a radiator and primary and secondary (auxiliary) electromagnetic energy reflectors (mirrors) assembled according to the scheme of a Cassegrain telescope. The Cassegrain antenna is widely used in radio communications, radar, and radio astronomy in the centimeter wavelength band.

The primary reflector, which is a paraboloid of revolution, determines the width of the directivity pattern of the Cassegrain antenna and forms a plane front of the radiated electromagnetic wave. A radiator, usually a horn, dielectric, helical, or dipole antenna, is located at the vertex of the primary reflector; such an arrangement significantly reduces the length of the lines feeding energy from the transmitter to the radiator. The auxiliary reflector, of smaller diameter, is a hyperboloid of revolution, one focus of which coincides with the focus of the primary reflector, and the second with the phase center of the radiator. A radiator with a directivity pattern of special shape and a low level of fringe radiation is used to reduce the dissipation of electromagnetic energy beyond the edges of the auxiliary reflector.

O. N. TERESHIN and G. K. GALIMOV

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
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References in periodicals archive ?
Subrahmanyan, "Photogrammetric measurement of the gravity deformation in a Cassegrain antenna," IEEE Antennas and Propagation Magazine, vol.
Wang, "Compensation for gravity deformation via subreflector motion of 65 m shaped Cassegrain antenna," IET Microwaves Antennas & Propagation, vol.
The mission requires a conventional Cassegrain antenna structure, with the main reflector a circular symmetric surface, while the sub-reflector a shaped one.
Gaussian type distribution is a good approximation in many systems, such as the output field of a Cassegrain antenna.
Casey, "A C/X/Ku-band dual polarized Cassegrain antenna system," IEEE Antennas and Propagation Society International Symposium, Vol.
The method used for deriving the large-scale errors of the Centro Astronomico de Yebes (CAY) 14 m Cassegrain antenna main reflector from measurements of the power radiation pattern at an elevation of 40 [degrees] is presented in this article as well as a method for correcting these errors by simple modifications on the secondary reflector.
An inexpensive and quick method to correct for the phase front distortions in the aperture field caused by the main mirror deformations in a large Cassegrain antenna has been presented.
Recently, FSS has been adopted in subreflector of Cassegrain antenna system to achieve frequency reuse, used to design band-pass radomes on the aircraft to reduce the out-of-band radar cross section (RCS) of antennas, and used in circuit analog absorber to expand its bandwidth [2].
The compact Cassegrain antenna, shown in Figure 6, was developed to receive direct broadcast satellite signals.
Bartlett, "Cassegrain Antenna with Dielectric Guiding Structure," US Patent No.
Also in this cassegrain antenna design method, the feed antenna is near the apex of main reflector and the feed waveguide and cables' lengths are reduced; therefore it causes reduced loss and noise.
The sensor comprises a high/low gain Cassegrain antenna, a quasi-optical multiplexer and cooled receivers covering frequencies from 30 to 110 GHz in eight 10 GHz wide channels.