Radiation enhanced dual-band MIMO antenna with mutual coupling reduction for 6G upper mid-band and mmWave wireless communication and sensing

Abstract

The rapid emergence of sixth generation (6G) wireless technology has made the design of antennas capable of operating across newly allocated 6G frequency bands increasingly demanding in recent years. In this article, a compact dual-band MIMO antenna with quasi-omnidirectional radiation pattern is presented for the 6G upper mid-band and mmWave band applications. Initially, a stub loaded monopole antenna with defected ground structure (DGS) is utilized to achieve dual-band with wide operating bandwidth.; however, the radiation performance is deficient. To achieve better omnidirectional radiation performance, an additional electrically coupled U-slot patch is proposed. This method offers better omnidirectional radiation performance. Subsequently, a 2-port MIMO is designed using the designed single element structure. And to reduce the mutual coupling between the MIMO antenna ports a slotted conducting parasitic element is proposed as an electric barrier. The designed decoupling structure offers a mutual coupling reduction of more than 9 dB, from − 16 dB to − 25 dB within the operating band. At the 6G upper mid-band the antenna shows a S11 < − 10 dB bandwidth from 7.1 GHz to 13.87 GHz. And at the mmWave band the antenna operates between 24.15 GHz and 27.2 GHz. In the functional operating band, the proposed antenna offers quasi-omnidirectional radiation pattern with a peak of more than 4.03 dBi and 6.43 dBi at 6G upper mid-band and mmWave band, respectively. Moreover, the proposed antenna offers excellent MIMO diversity performance, diversity gain (> 9.95) and envelope correlation coefficient (< 0.05) while maintaining a very low element spacing of 0.116λ0.