A Low-Profile Quad Element High Isolation MIMO Antenna for Enhanced Mobile Broadband Applications

Abstract

A novel quad-element bio-inspired virus-shaped Multiple Input-Multiple Output (MIMO) antenna with significantly improved isolation is proposed. Each radiator is based on a modified hybrid fractal antenna with a 50 Ω feed and incorporates a chamfered defective ground structure (DGS). To enhance the impedance bandwidth and radiation characteristics of the antenna, an elliptical slot and the DGS are employed. The placement of radiating elements in an orthogonal configuration is a key aspect of achieving the proposed MIMO configuration. In many MIMO designs, one of the primary challenges is achieving adequate isolation between antenna ports. However, in this design, we address this issue effectively by incorporating a swastik-shaped decoupling plane, which significantly enhances the isolation characteristics. The 4-port MIMO antenna is constructed on a Rogers RO3003 substrate and boasts compact dimensions of 57 × 57 × 0.787 mm³. The fabricated antenna has undergone experimental validation, confirming that it covers a substantial operational bandwidth of 41.57 GHz, ranging from 2.54 to 44.1 GHz, has a fractional bandwidth of 178%, and maintains isolation levels of less than −23 dB across its entire frequency range. The antenna design has achieved optimal MIMO performance, characterized by an Envelope Correlation Coefficient (ECC) value of ≤0.05, high multiplexing efficiency, minimal Channel Capacity Loss (CCL), and omnidirectional radiation properties. Hence, this design stands as an epitome for constructing super-wideband MIMO designs. The design metrics show the potential of the proposed antenna to operate with Enhanced Mobile Broadband (eMBB) which forms an integral part of 5G applications.