A frequency-reconfigurable electronically-steerable parasitic array radiator using microstrip patch antennas

A microstrip patch electronically-steerable parasitic array radiator (ESPAR) with continuous frequency reconfigurability is presented in this paper. Loading varactors are strategically placed on the radiating edge of all antenna elements to achieve a 15% continuous frequency tuning range, from 0.87 to 1.02 GHz. At each operating frequency, this ESPAR is able to scan from -20 to 20 degrees in the H plane. Therefore, this ESPAR is able to provide spectrum diversity in addition to the spatial diversity inherent in a frequency-fixed ESPAR. The underlying physics and design procedures of this ESPAR are presented. The return losses at different operating frequencies and scan angles, radiation patterns, realized gains, and third-order input intercept point (IIP3) are also measured.