A Single-Layer Reconfigurable Circularly Polarized Array Antenna With Dual-Pattern Radiation

This letter presents a single-layer reconfigurable circularly-polarized (CP) array antenna with dual-pattern radiation capability. The proposed design integrates four reconfigurable patches and a two-port magic-T-based feed network. CP switching is achieved using a single diode per patch, controlled by the switching voltage polarity, while port selection enables the sum and difference radiation patterns without affecting CP switching. The biasing mechanism eliminates the need for choke components through shorted perturbations and magic-Ts. Prototype measurements validate the proposed design, demonstrating 3% overlapped impedance bandwidths and port isolation exceeding −20 dB. Moreover, the fabricated 2×2 array successfully achieves CP switching, with peak realized gains of approximately 11 dBic and 10 dBic for the sum and difference patterns, respectively.