Broadband high efficiency circularly polarized active integrated antenna

This paper presents a broadband high efficiency circularly polarized active antenna integrated with class-E power amplifier (PA) at 2GHz. A single circular microstrip patch fed by a cross slot is employed as not only a broadband circularly polarized radiator but also as a harmonics-termination load network, which is directly connected with the class-E power amplifier output. A low cost PCB technology is employed in the circuit fabrication and a low voltage PHEMT transistor is used. A peak drain efficiency of 71.1% for the class-E amplifier is measured at 2.05GHz, together with a maximum radiated power of 28.2 dBm from the active integrated antenna (AIA). Power added efficiency (PAE) over 50% within a 17% bandwidth from 1.92GHz to 2.28GHz is achieved. Axial ratio below 3 dB is obtained over a 9% bandwidth from 1.99 GHz to 2.18 GHz.