Polarization Reconfigurable Antenna Array with Enhanced Bandwidth and Simplified Feed Network

A polarization reconfigurable 2I2 array with enhanced bandwidth is analyzed and designed, which consists of one simplified feed network and four antenna elements. Characteristic mode analysis is used to explain radiation character-istics of element antenna and slot coupling feed is employed to enhance the bandwidth. By changing the on-off state of four p-i-n diodes loaded in simplified feed network, linear polarization (LP), left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP) could be obtained respectively. The designed 2I2 antenna array with a compact size of 2.01 lambda(0) x 1.96 lambda(0) x 0.06 lambda(0) is simulated and measured. The measured-10-dB impedance bandwidth is 4.38-5.72 GHz for the LP state. The overlapped -10-dB impedance bandwidth and 3-dB axial ratio bandwidths are 4.32-5.44 GHz for both RHCP and LHCP states. The maximum gain reaches 7.9 dBi and the overlapped relative bandwidth of three polarization states is over 21%.