A Compact Circularly Polarized MIMO Dielectric Resonator Antenna Over Electromagnetic Band-Gap Surface for 5G Applications

We present a wideband circularly polarized (CP) multiple-input multiple-output (MIMO) dielectric resonator antenna (DRA) with enhanced diversity. In the DRA element, two diagonal edges of the DR were truncated at 45 to obtain a wider axial ratio larger than 0.65 GHz. The DRA element was excited by a cross-ring slot with specific slot-arm ratio through microstrip-line (MSTL) implemented at the backside of the FR4 substrate to generate CP fields. Small triangular stands at the edge of the DR were employed to hold it in place to avoid any degradation from the uncontrollable bonding agent used for attaching DR onto the FR4 substrate. The DRA achieved an impedance bandwidth better than 0.8 GHz with an antenna gain of 4.83 dBi. Using the DRA with the MSTL feed, two-element CP-DRA array was implemented with electromagnetic band-gap (EBG) structure etched onto the ground plane of the MSTL. The proposed architecture achieves isolation better than 26 dB over the desired frequency band without any performance degradation while maintaining its compact size in the array. Various diversity analysis was carried out on the implemented circularly polarized MIMO DRA. The measured results demonstrated that the proposed singly fed DRA with EBG on the ground plate is suitable for implementing wideband circular polarized MIMO antennas in a compact size.