Wideband Back Cover Microstrip Antenna With Multiple Shorting Vias for Mobile 5G MIMO Applications

This communication proposes a wideband and low-profile microstrip antenna for multiple-input multiple-output (MIMO) applications. By loading two sets of shorting vias and cutting two symmetrical slots on a rectangular patch, triple modes, including the monopole mode, the TM10, and TM01 modes, are excited simultaneously to achieve the wideband radiation in a relatively low profile. Four elements of the proposed antenna are placed in a sequentially rotated configuration for mobile MIMO applications with a small volume of59.2× 59.2×2.5mm3 (0.82\,\,λ ₀ × 0.82\,\,λ ₀ × 0.034\,\,λ ₀, whereλ ₀is the free-space wavelength at the center frequency). A cross-line fence is placed in the center to improve the isolation between adjacent elements. A prototype of the proposed MIMO antenna is fabricated and tested, with the measured −6-dB impedance bandwidth of 3.3–5.0 GHz, covering the N77/N78/N79 bands of fifth-generation (5G) requirements. The proposed four-elements MIMO antenna has the advantages of low profile, compact size, and wide bandwidth, providing a feasible solution of 5G mobile MIMO antennas on the back cover of the device.