Multiple input multiple output dielectric resonator antenna with circular polarized adaptability for 5G applications

In this paper, the concept of the circularly polarized agile, multiple-input multiple-output (MIMO) dielectric resonator antenna (DRA) structure for fifth generation (5G) new radio application in mobile terminal is presented. Two prototypes have been fabricated, namely one with cylindrical DRA (CDRA) referred as A1 and a second one with ring DRA (RDRA) named as A2. These practical realizations of dual-port MIMO antennas have been mounted on a Rogers 5870 substrate of octagonal shape with proper ground architecture. The proposed dual-port MIMO antennas have been excited with conformal probes and L-type feed network aiming to achieve circular polarization (CP). Measured impedance bandwidth of A1 and A2 are 21.2% (3.15–3.9 GHz) and 22.2% (3.12–3.9 GHz), respectively. Moreover, for both antennas low mutual coupling between ports with minimum isolation of $-20 $−20 dB over entire impedance bandwidth has been obtained by using triangular head slots in the ground plane. Measured axial ratio bandwidths in broadside direction $(\theta =0) $(θ=0) are 5.66% (3.26–3.45 GHz) and 4.25% (3.45–3.6 GHz), respectively. Maximum gains are 7.3 and 7.2 dBi, in that order. MIMO antenna parameters such as envelope correction coefficient, diversity gain (DG), mean effective gain and total active reflection coefficient are also calculated to verify MIMO performance parameters. The proposed antennas also demonstrate CP agility with insertion of concentric cylindrical shells of different radii.