Quad broadband circularly polarized CPW FED cleaver shaped extended UWB MIMO antenna for 5G,C, K and millimeter wave applications

A quad broadband circularly polarized coplanar waveguide fed octagonal slot antenna element and its two element spatial diversity configurations are presented. The antenna element comprises a cleaver shaped radiator along with multiple slots and L-shaped striploaded coplanar waveguide ground plane. Multiband circularly polarized performance is achieved by embedding L-shaped stub, quarter elliptical slot and a spiral slot on the edge of the ground plane. The overall volume of the single element is 0.21 λ_L × 0.25 λ_L × 0.02 λ_L. The antenna element has an impedance bandwidth of 3.73–29.27 GHz (154.79%) with quad circularly polarized band from 5.66 to 8.1 GHz (35.47%), 17.85–18.12 GHz (1.5%), 24.52–25.67 GHz (4.58%), and 27.48–27.62 GHz (0.51%). It has peak gain of 6.73 dB with peak radiation efficiency of 96%. The mutual coupling between the two ports of spatial diversity antenna is reduced by using a pair of modified symmetrical U-shaped decoupling structure between them. The spatial diversity antenna has total volume of 0.48 λ_L × 0.25 λ_L × 0.02 λ_L with impedance bandwidth of 3.78–29.28 GHz (154.27%) and circularly polarized performance in the frequency range of 5.31–7.35 GHz (32.23%), 21.4–21.71 GHz (1.44%), 23.11–23.54 GHz (1.84%), and 24.9–25.68 GHz (3.08%). It has an intra-port isolation > 16 dB, ECC < 0.008, DG of 9.998 dB and CCL < 0.4 Bits/s/Hz at all operating frequencies. A good match between the simulated and experimental results is achieved for both configurations.