Polarization Reconfigurable Antenna Array with Enhanced Bandwidth and Simplified Feed Network

A polarization reconfigurable 2×2 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 2 ×2 antenna array with a compact size of 2.01λ
0
× 1.96λ
0
×0.06λ
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%.