Compact, dual-band, equal-beamwidth radiometer antenna

The authors summarize an investigation into a suitable antenna configuration for a compact radiometer which operates over two distinct frequency bands (20-4 GHz and 31.3-31.7 GHz) and contains 90% of the energy in a 4 degrees cone. The salient feature of this antenna system is that its far-field secondary radiation pattern exhibits almost constant beam shape over the entire operating frequency range. A single offset ellipsoid reflector configuration fed by a profiled wideband corrugated horn was chosen to yield a well-defined Gaussian main beam with low sidelobes. The primary feed horn has been designed to perform well over two widely separated frequency bands. The antenna far-field radiation patterns in the two principal planes at 20.0, 2.0, and 31.5 GHz are shown.<>