Tracking antenna architectures based on a planar two-port microstrip patch mixer antenna

This paper describes the behavior of a compact two-port integrated mixer active antenna element with low cross polarization, high two-port circuit isolation, and good mixer detection sensitivity. Using this element as an elemental building block, a self-tracking antenna array has been realized which uses an in-band carrier signal for self calibration. The array is relatively insensitive to absolute carrier power level and is capable of tracking incoming signals over ±80°. By minor alteration of the antenna topology, a minimum complexity variant of a heterodyne retrodirective array has been demonstrated over a ±40° retransmission angle. Finally, the use of the antenna in conjunction with an injection-locked voltage-controlled oscillator (VCO) is included in order to demonstrate ±35° phase-shifterless beam steering