Three-Port Three-Polarized Dielectric Resonator Antenna With Omnidirectional Radiation

In this letter, a three-port omnidirectional cylindrical dielectric resonator antenna (DRA) is presented. The design makes use of the TM01 delta and two degenerate HEM21 delta modes of the cylindrical DRA. The resonant features of the two modes are investigated and their resonant frequencies are different. The TM01 delta mode is fed with horizontal magnetic current, which is obtained by four slots. The input impedance of the antenna is affected by the length of the open-circuit stub, which is the end of the feed network. Thus, the resonant frequency of the TM01 delta mode can be moved to that of the HEM21 delta one through the proposed exciting method. Two HEM21 delta modes are excited simultaneously by a 90(degrees) hybrid coupler to realize right- and left-hand circularly polarized omnidirectional radiation. Based on the three modes, a three-port three-polarization DRA with omnidirectional radiation for indoor communication applications is fabricated and measured. The results indicate that the S-parameters, field characteristics, and communication performance are satisfactory in the operating band.