Active integrated antennas using planar quasi-Yagi radiators

This paper reviews the development of several types of active integrated antennas at the authors group based on a novel planar quasi-Yagi structure which has broad bandwidth (>50%), high efficiency (>93%), low cross-polarization (<-13 dB), good front-to-back ration (>13 dB) and extremely compact size. The basic performances of the elementary quasi-Yagi antenna is first described, followed by several application examples including a high-efficiency push-pull power amplifier, a 5.8 GHz quadrature direct conversion receiver, as well as a 60 GHz self-oscillating mixer front-end.