Cassegrain antenna

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

Electronically scanning dual beam antenna

Abstract: Electrically scanning dual-beam antenna intended to be installed on a moving platform and in particular on a satellite. The antenna according to the invention comprises a single complex reflector (104), the reflectivity of which is sensitive to the polarisation of the illumination, and two arrays of sources of orthogonal polarisations which illuminate the complex reflector in an "offset" geometry. The complex reflector consists of two reflectors placed one in front of the other, along the direction of propagation of the beams; the first reflector (114) being transparent for a first linear polarisation and reflecting for the orthogonal polarisation, and the second reflector (124) being reflecting for at least the second polarisation. The two resultant beams are thus separated in space, along a direction parallel to the trajectory of the platform. The electronic scanning is performed in a plane perpendicular to the plane of the orbit. Application to stereoscopic radars for earth observation from a satellite, and to radiometry.

Experimental Synthesis of a Feed Pattern with a Dense Focal Plane Array

Abstract: The 8×9 element dense tapered slot array operating over 1-7 GHz range is used to synthesize a dual-band (2.215-2.375 GHz and 4.770-5.020 GHz) feed for a F/D=0.35 reflector. Only 25 elements are excited in a concentric ring manner to simulate a conventional coaxial feed. Not only experiments, including mutual coupling effects, but also array simulations using the cos2 element power pattern give a satisfactory approximation. Recommendations of how to choose the sufficient overall dimensions of the dense array feed are developed on the basis of the focal field distribution analysis. Power losses of no more than about 5% at the boundaries of the given band relatively to the central frequency serve as a criterion determining the maximal efficiency of the reflector aperture.

Spherical double reflector antenna

Abstract: There is described a double reflector antenna arrangement having a fixed spherical-segment main reflector and at least one spherical subreflector surface concentrically arranged relative to the main reflector, which spherical/spherical double reflector antenna is particularly useful as a non-moving communication antenna capable of operating with one or more synchronous satellites. Multiple beam operation is effected by providing a feed with each spherical subreflector, wherein the position of the feeds relative to the main and subreflecting surfaces is optimized as a function of the antenna F/D ratio and especially the associated subreflector radius as defined by the spherical center point of the main reflector.

A low-blockage dipole array reflector antenna feed for the lower microwave frequencies

Abstract: An antenna is described which was devised as a feed for a small axisymmetrical paraboloid reflector at an operational frequency of just over 1 GHz. The antenna consists of a broadside array of two dipoles on a printed circuit board (PCB), joined by a common transmission line. Each dipole is backed by a small strip reflector. With this simple array, which has one central feed point, the H -plane radiation pattern can be varied independently of the E -plane pattern. In addition, the aperture blockage of the feed is small.

Synthesis of the aperture field for a contoured beam

Abstract: This paper presents a method to synthesize the optimum contoured beam obtainable from an aperture of a given size. The practical implementation by means of a multi-feed antenna and a shaped reflector antenna is also considered. >