A Low-Profile Reconfigurable Cavity-Backed Slot Antenna With Frequency, Polarization, and Radiation Pattern Agility

A novel cavity-backed slot antenna, with the ability of reconfiguring the frequency, polarization, and radiation pattern, is presented. The reconfigurability is realized by electronically controlling the state of switches between two crossed slots etched on the surfaces of a substrate integrated waveguide cavity. The antenna is capable of simultaneously changing the radiation patterns between forward and backward directions, switching the polarization among two orthogonal linearly polarized (LP) and two orthogonal circularly polarized (CP) states, tuning between three frequency bands for LP states and between two frequency bands for CP states. A fully functional prototype is developed and tested, demonstrating the antenna with measured gains of approximately 4 dBi and stable unidirectional radiation patterns for all 20 states. In addition, the proposed design possesses a low profile of 0.01 free-space wavelength.