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.