Graphene-based frequency selective surface decoupling structure for ultra-dense multi-band plasmonic nano-antenna arrays

Abstract

A four-layer graphene-based frequency selective surface (FSS) is proposed to reduce the mutual coupling in ultra-dense plasmonic nano-antenna arrays for multi-band Ultra-Massive MIMO communications. In the proposed structure, graphene is utilized as a cross patch FSS, which is low-profile and tunable. The FSS structure shows a wide stop-band (-15 dB) from 1.1 THz to 1.7 THz. By inserting the FSS structure between the elements of the nano-antenna array, a high isolation of -25 dB with a 15 dB fall is achieved, which indicates that mutual decoupling effects are suppressed for both two-element and four-element arrays. The radiation patterns are given to confirm that the proposed FSS structure can improve the performance of multi-band THz antenna arrays with negligible influence on the nano-antenna radiation performance. Finally, it is asymptotically shown that the mutual coupling experienced by the nano-antenna with the FSS structure is negligible even in the presence of very large number of closely integrated elements.