Compact U6G Massive MIMO Antenna Arrays With Double-Layer Partial Reflective Decoupling Layers for Mutual Coupling Suppression

In this paper, a systematic decoupling strategy of two partial reflective decoupling layers (PRDLs) and dummy decoupling probes (DDPs) is utilized to suppress the complicated couplings in a ±45° dual-polarized, compact antenna array operating at Upper 6 GHz (U6G, 6425–7125 MHz) bands. Finely engineered neutralization electromagnetic waves are introduced by two PRDLs to counteract the original couplings. Two layers of PRDLs are placed above the antenna array in a step-by-step manner to gradually cancel out several major couplings while DDPs are placed around the antenna elements to reduce the remaining couplings. The measurement results of the
$6\times4$
staggered quadruple folded dipole (QFD) array prototype with power combiners show that within the U6G band, the isolations between all ports are improved to more than 21 dB with good port matching performance, while the radiation pattern and envelope correlation coefficient are also in good condition, which verifies the correctness and effectiveness of the proposed decoupling method, especially in very compact U6G Massive MIMO antenna arrays.