Neutralization‐Line Decoupling for High‐Density Dipole‐Patch MIMO Arrays

ABSTRACT A neutralization‐line (NL) decoupling method with a dipole‐patch‐antenna (DPA)‐oriented design rule is proposed for high‐density arrays. The NLs are directly connected between adjacent patches near their open ends, where the voltage is maximum, and the current is minimum. An equivalent‐circuit model and parametric analysis demonstrate that the connection position and NL impedance jointly control the compensating coupling. The design rule is validated in dual‐, tri‐, and twelve‐element MIMO configurations as well as 1‐D and 2‐D linear arrays. A fabricated twelve‐element prototype achieves a 200 MHz impedance bandwidth from 3.4 to 3.6 GHz, isolation exceeding 16 dB, a measured peak broadside gain of 6.3 dBi, and far‐field envelope correlation coefficients below 0.1. These results demonstrate the method's applicability to high‐density multi‐element DPA arrays.