Design of Planar, Wideband, Multi-Polarization Reconfigurable Filtering Antenna

A planar, wideband, multi-polarization reconfigurable filtering antenna is proposed. By controlling the state of PIN diodes, the operation states of the filtering antenna can be switched among linear polarization (LP), left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). The filtering antenna consists of a driven patch, a parasitic patch, and an established reconfigurable feed network. Two radiation nulls can be generated at the lower and upper band-edge in all operation states through interaction between the driven patch and feeding network. A pair of U-slots is etched on the driven patch to obtain the extra radiation null to further improve the sharp roll-off rate at the upper band-edge. The optimized prototype was fabricated and tested. The measured results, in good agreement with the simulated values, demonstrate that the filtenna has a wide -10dB fractional bandwidth: 15.6%, a realized gain value over operational bandwidth of 7.7 ± 0.5 dBi, and stable radiation performance. Furthermore, the filtenna presents a good out-of-band rejection level.