A Cross-Shaped Dielectric Resonator Antenna for Multifunction and Polarization Diversity Applications

This letter proposes a multifunction cross-shaped dielectric resonator antenna (DRA) with separately fed broadside circularly polarized (CP) and omnidirectional linearly polarized (LP) radiation patterns. These distinct radiation patterns are achieved in overlapping frequency bands by exciting two different modes in a single dielectric resonator (DR) volume. This letter also investigates the effect of the feeding geometry on the mutual coupling between the modes and concludes that an asymmetric feeding degrades the orthogonality of the modes and thus increases the interport coupling coefficient. By using a symmetric feeding, the coupling coefficient can be significantly reduced to below - 30 dB in the frequency band common to both operation modes. The experimental results show a good agreement with simulation and demonstrate a broadside CP operation over a bandwidth of 6.8%, which overlaps with the omnidirectional LP impedance bandwidth of 38.5%. The proposed antenna could be used not only as multifunction, but also as polarization diversity antenna due to the overlapping dual-feed CP and LP operation.