Offset reflector antennas: Design, computation, construction and pattern measurements

The test of active and passive methods for the purpose of object recognition in the frequency region from 32 to 90 GHz, requiring a series of antennas with different half beam widths and with an axial symmetric radiation pattern for orthogonal linear polarization is considered. These requirements are met by the principle of a single offset-reflector antenna with a corrugated feed. The design procedure for this antenna system is described. Computation of the scattered pattern is based on the current distribution method. The primary pattern is determined by experiment as well as theory. For construction of the antennas, a fiberglass technique was applied, combined with a special method for shaping the parabolic reflectors. Measured and computed results show the validity of the established design rules.