Dual polarized sinuous antenna and ultra wideband feed design and integration

Abstract

The designs of multi-arm planar sinuous antennas and their feeding networks are presented in this thesis for operation from 2-18GHz. The sinuous antenna's superior ultra wideband performance and dual polarization capability makes it ideal for both civil and military applications like direction-finding (DF) systems. The sinuous antennas generate broadside patterns with dual linear or circular polarization over wide beamwidths with good gain over the entire frequency band. The bandwidth of the sinuous antenna is virtually unlimited and is only restricted by the design of the feed network. There has been very little publicized research geared towards this antenna due to its complicated feed network design and integration. In this thesis novel feed designs are presented in the form of ultra wideband balun structures, symmetrical 3dB 90° directional couplers, and their integration into the system. In addition to the specific designs, modifications were made to the sinuous antenna, while new techniques were developed with concentration on theoretical and practical implementation to minimizing size, weight, and costs. The results presented for the performance of the sinuous antenna show improvements over existing designs.