Compact S/X Dual-Band Coaxial-Fed CP Polarizer for Satellite Communications

Satellite communications employs circular polarization (CP) to circumvent thewell-known phenomenon known as Faraday Rotation, where the ionosphere rotates the horizontal and vertical polarization components resulting in signal degradation especially at lower frequencies, i.e., VHF and L-band, and in tropical regions of the earth. Satellite circularly polarized antenna feed technology commonly employs bulkyand lossy 90-degree hybrid combiners to convert linear polarization to circular polarization, which results in a higher noise figure for receive applications and a less repeatable and more difficult design to tune and manufacture. This thesis aims at designing, modeling and simulating a prototype S/X dual bandCP feed/polarizer utilizing a technique known as the “Spread-Squeeze” polarizer, which offers the advantages of compact size, ease of manufacture, and lower loss and noise figure, relative to the current technology that often employs an external 3-dB hybrid combiner. Ansys High Frequency Structure Simulator (HFSS), a commercial electromagnetic modeling and simulation tool, is used for the simulations. Further, this thesis aims to characterize the performance of the dual feed hornwith respect to aperture efficiency, that is, the degree to which the feed horn illuminates the parabolic reflector.