A Compact Wideband Antenna With Suppressed Mutual Coupling for 5G MIMO Applications

A novel miniaturized wideband dual-polarized antenna, based on cross magnetic dipoles and a backed cavity, is proposed in this letter for multiple-input–multiple-output (MIMO) applications. The dipoles with exponential curvature edges deliver inherent wideband character to the radiator. Four parasitic resonators are introduced to miniaturize the top radiator's conducting area and lower the Q-factor of the whole structure, enhancing the antenna's impedance matching. Different from conventional direct-fed cross-dipole antennas, a wideband hybrid ring coupler is applied to excite the two dipoles simultaneously in-phase/out-of-phase to generate the ±45° polarization. The dimension of the proposed antenna is 42.5 mm × 42.5 mm × 18 mm, which is only 0.48
λ_L
× 0.48
λ_L
× 0.2
λ_L
at the frequency of 3.4 GHz. The corresponding MIMO array is studied, showing a low mutual coupling and envelope correlation coefficient level across the band, and an outperforming front-back-ratio performance. The antenna is prototyped and measured. The measurement results agree with those of the simulations well .