A Circular Polarization-Reconfigurable Antenna With Enhanced Axial Ratio Bandwidth

Acircular polarization (CP)-reconfigurable antenna array with enhanced axial ratio (AR) bandwidth and high gain is proposed in this letter. By loading the tuning resistor on the annular coupling slot, the AR bandwidth of the initial design is significantly improved. Furthermore, the elliptical grid-slit patch is employed to mitigate the decreased AR performance caused by the parasitic effect from PIN diode switches while improving the gain. A prototype of a 2×2 array is developed, fabricated, and measured. Experiments show that the AR bandwidth is 31.6%, while the measured peak gain is up to 16.3 dBic.