Polarization-Reconfigurable Cylindrical Dielectric Resonator Antenna Excited by Dual Probe With Tunable Feed Network

A polarization-reconfigurable cylindrical dielectric resonator antenna (DRA) based on a tunable feed network is presented in this paper. $\textrm {HEM}_{11\delta } $ modes excited by two-port side-fed probes are adapted to design the proposed DRA. Polarization reconfigurable characteristic can be obtained by a tunable feed network that consists of Wilkinson equal power divider, parasitic elements used for phase shifters, and p-i-n diodes between them. By controlling the four pairs of p-i-n diode switches to active corresponding elements as effective phase shifters, two sources with equal amplitude and 0° or ±90° phase differences are obtained to generate linear-polarized (LP) or circular-polarized (CP) states, respectively. A fully functional prototype of the proposed antenna with the dimension of $0.55\lambda \times 0.55\lambda \times 0.14\lambda $ has been designed, fabricated, and tested. The results indicate that the proposed DRA can achieve the bandwidths of more than 30% for both impedance bandwidth and 3-dB axial ratio bandwidth at CP states, and two LP states with the impedances of 6.3% and 9.5%. Stable directional patterns and realized gains are obtained for all the states. These performances make the proposed DRA suitable for polarization diversity scenarios in communication systems.