Design and characterization of a circular ring monopole antenna and its MIMO configuration for sub-6 GHz, sub-7 GHz and mm-wave 5G applications

Abstract In this paper, a circular ring monopole antenna, along with its MIMO configuration for sub-6 GHz, sub-7 GHz and mm-wave 5G applications is presented. The single element spans a wide range of frequencies in the sub-6 GHz and mm-wave regions, including a triple-band covering 1.9–6 GHz, 23.3–33.5 GHz, and a super-wide band starting from 37.5 GHz. A two-element MIMO antenna, derived from the single element, has been developed to operate in both frequency regions. It meets the −10 dB criterion with a bandwidth of 4.8 GHz (3.2 to 7.3 GHz) in the sub-6 GHz/sub-7 GHz spectrum. Additionally, the antenna exhibits a super-wide band in the mm-wave region starting at 30.4 GHz. The design covers key bands such as n78, LTE band 46, n96, 39 GHz band, 41 GHz band and more, assigned for 5G sub-6 GHz, sub-7 GHz and mm-wave applications. Improved isolation from 12 dB to 18.5 dB is achieved through a simple decoupling line structure between elements. The proposed MIMO antenna (75 × 56.4 × 1.52 mm 3 ) exhibits a peak gain of 9.8 dBi, high isolation (18.5 dB), low envelope correlation coefficient (ECC <0.016 ), high diversity gain (DG > 9.995), and efficiency (< 97%).