A Frequency-Reconfigurable Single-Feed Zero-Scanning Antenna

A frequency-reconfigurable zero-scanning single-feed antenna combining two planar back-to-back quarter-wave patch antennas is presented. The reconfiguration mechanism is implemented using open-circuited stub-loaded varactors, which are connected to the sides of the differentially fed radiating apertures. Through individual tuning of the bias voltages to these varactors, the resonance frequency and relative phase of the two patches can be adjusted. This allows continuous tuning of the operation frequency and scanning of a radiation null in one plane. The antenna is optimized to have a zero-scanning zenith angle from −28° to +28° over a frequency tuning range of 16%. An antenna prototype has been fabricated for experimental validation, and the achieved measurement results confirm the potential of the design concept.