An Electrically Reconfigurable Circularly-Polarized Planar Array Antenna With Built-In Bias-Isolation Mechanism

This paper proposes a novel design of a reconfigurable microstrip array antenna for circular polarization (CP) switching function. The proposed array is implemented in a 2\times 2 arrangement using four patch elements and a feed network. The bias-isolation mechanism is an integral feature of this array design, and it is facilitated by the short-ended microstrip lines and planar magic-Ts. By this approach, both the radiating elements and feed structure ensure the straightforward RF-DC isolation method with no auxiliary passive components and filters. Also, with the superb integration of these two techniques, the entire array is viable in a single-layer configuration, featuring design freedom for a larger array. Furthermore, the CP switching function can simply be achieved by controlling the bias state of the diodes. To verify the proposed concept, prototype antennas are fabricated and tested. The measured results demonstrate that the proposed array can function as a CP reconfigurable antenna with simple bias-isolation method.