Self-Oscillating Circularly Polarized Active Integrated Antenna Using Zeroth-Order Resonators With Boosted Conversion Efficiency

A new self-oscillating circularly polarized active integrated antenna (CPAIA) featuring boosted dc-to-RF conversion efficiency is proposed and demonstrated in this letter. The conversion efficiency, 40% better than the second best design in the literature, is achieved by innovative integration of a CP exciter with a pair of anti-symmetrically arranged parasitic radiators. The CP exciter is a linearly polarized self-oscillating active dipole antenna consisting of zeroth-order resonators and a crosscoupled pair oscillator. In addition to oscillate and radiate a linearly polarized electrical field into space, it is responsible for coupling half of the oscillating power into the pair of parasitic radiators to excite another linearly polarized electric field spatially and temporally orthogonal to the original one for CP operation. The proposed CPAIA is fabricated and tested at 879 MHz, and is compared with the state-of-the-arts in the literature. Good agreement between the simulated and measured results validates the design concept, and the performance summary table highlights the advantages of the proposed design.