Ultra-compact universal polarization X-band unit cell for high-performance active phased array radar

This paper describes the design of a high-performance X-band antenna array for a tileable dual-linear and circularly-polarized active phased array antenna. A 4×4 unit cell prototype was built and integrated with state-of-the-art T/R modules conforming to an active tile array. The use of cross patches as a stacked configuration add polarization purity while maintaining high bandwidth. The antenna is fed with four probes to implement a balanced differential feeding network in order to create a 180° phase delay between the opposing probes. This provides high polarization purity while maintaining the ability to do quadrature feeding for circular polarization. Preliminary results using uncalibrated patterns show promise for the potential implementation of the active array for circular and linear polarization based on an ultra-compact tile architecture.