Equilateral triangular dielectric resonator based co-radiator MIMO antennas with dual-polarisation

In this study, two types of dielectric resonator antennas (DRAs) with dual-polarisation are proposed and investigated for multiple-input multiple-output (MIMO) applications. The first design is a dual-slant polarised DRA and exhibits the measured impedance bandwidth of 8.2% (5.27-5.72GHz) and 11.2% (5.05-5.65GHz) for Port1 and Port2, respectively. Across the operating frequency band, the isolation between the input ports is better than 22dB and the measured gain of the antenna varies in the range of 5.99-6.38dBi. The second design developed here is a dual-linearly polarised DRA which is able to provide horizontal and vertical polarisations and is realised by integrating a two-stage rat-race coupler with the DRA for excitation purpose. In this case, the measured impedance bandwidths are 11.81% (5.18-5.83GHz) and 15.18% (4.93-5.74GHz) for Port1 and Port2, respectively, and the inter-port isolation is better than 20dB throughout the operating frequency band. The antenna exhibits the measured gain variation of 5.94-6.48dBi for Port1 and 5.54-5.86dBi for Port2. Furthermore, for both the antennas, the envelope correlation coefficient is below 0.0004 throughout the bandwidth and the total active reflection coefficient is better than -10dB, confirming the good diversity and radiation performance.