Communications Satellite Corporation

Randall W Kreutel, Jr

Sigmund H Hanell

A frequency conversion interface is disposed between the main and subreflectors in a multiple beam antenna system so that the antenna system amplification factor will be defined by m=(f.sub.1 /f.sub.2).multidot.(.omega..sub.1 /.omega..sub.2), to permit large main reflector to subreflector area ratios while maintaining small amplification factors.

Scheme for aberration correction in scanning or multiple beam confocal

A modular arrangement of directional RF filters provides frequency multiplexing of signal sources at earth stations which are transmitting on two orthogonal polarizations. Each of the modules consist of a pair of 3 dB hybrid couplers coupled to each other through identical bandpass filters such that a signal applied to one of two input ports is output exclusively through an associated one of two output ports. The passbands of each of the modules are mutually exclusive. The output ports of each module are coupled to an output port of two adjacent modules, and two main outputs are taken from the two outer modules. The signals from the two main outputs are applied to two antennas having mutually orthogonal polarizations. The present invention may also be used as a demultiplexing receiver.

High power multiplexer for dual polarized frequency reuse earth stations

Intermodulation product frequency signals in an active phased-array antenna are spacially filtered by using the beam forming and steering network as a processor to select the intermodulation beam pointing directions such that they will not interfere with the desired beams.

Intermodulation product suppression by antenna processing

A lens system is formed of spaced coaxial hyperboloidal primary and secondary lenses, each having a convex surface described by a hyperboloidal eccentricity equal to the refractive index of the lens with the lenses mounted with their convex surfaces facing each other, and with the lenses having equal beam deviation factors. A feed array is integrated with the secondary lens, with the feed array comprising array elements printed on a substrate which, in turn, is backed by a ground plane. A beam forming and control network is directly connected to the substrate at the ground plane.

Integrated confocal electromagnetic wave lens and feed antenna system

A technique is disclosed for restoring the orthogonality of dual polarized signals in frequency reuse communications systems. The technique may be characterized as polarization coding at the transmitter and polarization decoding at the receiver. Coding and decoding is accomplished solely by means of phase shifters and sum and difference networks which are lossless in the dissipative sense. The required phase shifts are determined by defining the transmission media in terms of a transmission matrix. All depolarization effects including those attributable to antennas, feeds and media are lumped into this matrix. The transmission matrix may be determined empirically, and the phase shifts fixed for a given transmission media. Where the characteristics of the transmission media vary with time due to atmospheric and other effects as is the usual case, an automatic, closed loop orthogonalization network is employed wherein a pilot signal is generated at one or both ends of the communications system and used to derive error signals for phase shifter control. The technique disclosed is applicable to systems using either linearly or circularly polarized waves.

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Rockville, MD, United States of America

Randall W Kreutel, Jr