Cassegrain antenna

About: Cassegrain antenna is a research topic. Over the lifetime, 3207 publications have been published within this topic receiving 28278 citations.

A shaped reflector design for the DirecTv direct broadcast satellite for the United States

Abstract: A design for the DirecTv DBS (direct broadcast satellite) coverage of the United States using a single shaped reflector is presented This design is interesting and challenging because of the high ratio of the area of the coverage to the area of the pencil beam obtained using an unshaped reflector (>40) For the initial multifeed study, a parabolic reflector with a diameter of 96" was considered After a detailed trade-off study, a design with a 56-element feed array was chosen For the shaped reflector approach, a diameter of 85" was chosen after an initial trade-off study A sensitivity study using a 'potato-chip' distortion model was conducted >

Multiband feed using coaxial configuration

Abstract: In a communication satellite, multiple frequency bands are used for transmitting and receiving communication, data and tracking signals. In this paper we present design, analysis and test results of a dual-aperture coaxial multiband feed horn. The coaxial configuration is particularly useful for the frequency bands that are widely separated. Our design goal was to operate at S-, Ku-, K- and Ka-bands. In our design the Ku through Ka bands are launched through a multiflared circular horn while the S band is launched through a stepped and flared coaxial horn sharing a common axis with the circular horn (Fig. 1). A method of moment (MoM) based software is developed to analyze the structure. It is found that for the S-band, the aperture impedance significantly affects the electrical performance. For the high frequency bands, the mutual coupling between the circular and coaxial apertures plays an important role on the performance. The simulated results including mutual coupling effects agree well with the measured data. This multiband feed design allows a compact, low weight, single offset reflector configuration as opposed to a Cassegrain antenna system that requires two separate feeds and a dichroic subreflector to accommodate multiple bands.

Synthesis and rigorous analysis of omnidirectional ADE antenna with shaped main reflector described by local conic sections

Abstract: This work investigates the synthesis and analysis of omnidirectional dual-reflector antennas. The body-of-revolution subreflector is generated by a single conic section while the shaped main reflector is generated by a combination local conic sections, sequentially concatenated to each other. The main-reflector is shaped to radiate, under GO principles, a prescribed power density in the elevation. As case studies, four representative axis-displaced ellipse (ADE) configurations are synthesized to provide a sectoral coverage in the elevation plane. Two different ray structures are considered: with a real or a virtual main reflector caustic. For a rigorous analysis of the antenna, a hybrid technique based on Mode Matching and Method of Moments is employed.

Substantially frequency-independent aberration correcting antenna arrangement

Abstract: The present invention relates to an antenna arrangement which uses a large offset spherical main reflector to communicate with several, spaced-apart, remote locations. Large aberrations caused by the main reflector are corrected by a first subreflector forming a small image of the main reflector at a conjugate image surface and a second subreflector which is disposed at the image location and is shaped to correct for the aberrations caused by the main reflector. Such correction is, to a good approximation, frequency independent and provides aberration free operation at feeds adjacent each other and associated with remote locations having small differential angles of incidence on the center of the main reflector.

Sub-reflector for dual-reflector antenna system

Abstract: An antenna includes a feed generating a communication signal. A sub-reflector is positioned to reflect the communication's signal to form a sub-reflective signal. A main reflector is positioned to reflect the sub-reflective signal. The sub-reflector has an elliptical rim.