Polarization-Reconfigurable Circularly Polarized Planar Antenna Using Switchable Polarizer

A novel polarization-reconfigurable planar antenna is presented. The antenna consists of an electronically reconfigurable polarizer integrated with a printed slot. By changing the states of the PIN diodes on the polarizer, the linearly polarized (LP) waves radiated by the slot can be converted to either right-hand circularly polarized (RHCP) or left-hand circularly polarized (LHCP) waves. The polarizer contains 16 unit cells arranged as a 4 × 4 array. The antenna radiates RHCP waves if the PIN diodes on the top side of the polarizer are switched ON, while LHCP waves are radiated if the PIN diodes of the bottom side of the polarizer are switched ON instead. The physical mechanisms of the antenna are discussed and the parametric study is carried out by full-wave simulations. To verify the concept, one prototype at 2.5 GHz is designed, fabricated and measured. Good agreement between the measured and simulated results is obtained. The antenna achieves a gain ? 8.5 dBic in both RHCP and LHCP with aperture efficiency of 70%. Advantages of the proposed design include electronicallyreconfigurable polarizations for RHCP or LHCP, low profile, low cost, high isolation between the DC bias circuit and RF signals, high power handling capability and easy extension to large-scale arrays without increasing the complexity of the DC bias circuit. To the best knowledge of the authors, this is the first report of an electronically polarization-reconfigurable circularly polarized antenna with a single-substrate polarizer.