A Low Phase Noise Self-Oscillating Active Antenna

A self-oscillating active antenna with low phase noise at 2.4GHz is presented in this work. In the positive feedback path of the oscillator, a well-designed resonant network consisting of a microstrip antenna and an open-loop resonator provides a high group delay that suppresses the phase noise. The simulated phase noise is -125dBc/Hz at 100kHz offset frequency, and the efficiency of DC-RF is up to 30%. The proposed structure is planar which is attractive to the low-cost and compact wireless system.