Beam Squint Compensation in Circularly Polarized Offset Reflector Antennas Using a Sequentially Rotated Focal-Plane Array

The problem of beam squinting in circularly polarized offset reflector antennas is solved by using a novel focal-plane array concept that consists of sequentially rotated linearly polarized elements. This concept can be used to facilitate beam steering in full-duplex communication with satellite Internet (VSAT) operating in the Ka-band. A prototype consisting of a 75-cm offset dish illuminated by a 2 ×2 array of sequentially rotated aperture-coupled microstrip antennas was developed and tested at 20 GHz. Experimental results clearly demonstrate the removal of the beam-squint and resulted in an axial ratio (AR) below 1 dB within the 1-dB beamwidth of the main beam.