A Compact Polarization-Reconfigurable and 2-D Beam-Switchable Antenna Using the Spatial Phase Shift Technique

In this paper, a compact patch array antenna with reconfigurable polarizations and 2-D switchable beams is developed based on the spatial phase shift technique. A compact element antenna is proposed with switchable ports for implementing the spatial phase shift technique, which is composed of a square driven patch, two sets of perturbation segments connected to the driven patch via p-i-n diodes for polarization diversity, a parasitic patch, and three switchable feeding probes integrated with a designed single-pole triple-throw switch. For circular polarized waves, individual excitation at the three feeding probes can obtain a 90° or 180° phase difference because of the spatial relative position between the feeding probes. The radiation beam and polarization of the2× 2array antenna can be dynamically reconfigured among nine beams and dual-circular polarization modes by properly switching these feeding probes and perturbation segments. In addition, the 3 dB axial-ratio bandwidths are effectively enhanced by using the spatial phase shift technique. To validate the proposed concept, a prototype operating at 4.8 GHz is designed, fabricated, and measured. The measured 10 dB return loss bandwidths for all operating states can cover a frequency band of 4.63–5.07 GHz with measured gains ranging from 7.5 to 10.5 dBic.