Recent progress in switched beam single element antennas

This paper covers five different types of single element beam scanning antennas under electronic switch control. Firstly, a rectangular spiral antenna with shorting and open switches is presented. Following that, its polarization and other antenna parameter limitations are addressed. Then new structures, namely: star strip, star patch and square loop antennas, introduced to overcome the polarization problem in the spiral antenna, are covered. All these new antennas are symmetrical, and have 4 feeding points. When excited individually, these feeding points generate four tilted beams of the same characteristics in different quadrants, yielding a complete beam scanning antenna. The gains for these three antennas for each of the feed configurations are approximately 8.1 dBi and the polarization dominance is in the E_thetas direction. Finally future work on implementing switches including MEMS on the ground plane of the antennas for switching the beam of the antennas is outlined.