Unified Integration of Self-Oscillating Mixer-Antenna for Compact Receiver Frontend

A method of integration for unifying active device and receiving antenna to realize a low-loss and compact single-ended self-oscillating mixer-antenna (SOMA) frontend is proposed in this work, through an experimental prototype demonstrated over X-band. Stability analysis of the active device is performed first, and a shorted microstrip line is then used as a source feedback to destabilize it. Subsequently, rectangular patch antenna impedance behavior is studied, and eventually designed to satisfy the oscillation requirement at LO frequency of 10.8 GHz, and also to exhibit stability and good radiation performance at RF frequency of 10 GHz. Dual band microstrip matching network is designed for simultaneously satisfying the oscillation condition at LO and the impedance matching at IF for measurements. It is observed experimentally that the oscillation occurs at LO frequency of 10.86 GHz. Subsequently, a 10 GHz RF input signal is fed, which results in a self-oscillating mixer configuration with an IF signal of 0.86 GHz at the output. From measurements, the proposed SOMA exhibits a conversion gain of 10 dB, and input power 1-dB compression point of -10 dBm.