Design of Wideband Self-Decoupled Millimeter-Wave MIMO Magnetoelectric Dipole Antenna Array Using Higher-Order Electric Dipole Modes

A self-decoupling method that relies on the combination of higher-order electric dipole modes is investigated for the multi-input multi-output (MIMO) millimeter-wave (mm-wave) magnetoelectric (ME) dipole antenna array. The study demonstrates that by appropriately designing the size of planar dipole to make its 1-<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</i> and 1.5-<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</i> modes close to the operating magnetic dipole mode, the coupled currents of these two modes in the adjacent ME dipole antenna can counteract each other at the center feeding position. As a result, the current intensity there becomes rather weak, and hence an extremely low level of mutual coupling can be obtained without requiring any additional decoupling structure. For verification, a 1 × 2 MIMO ME dipole antenna array operating at 30 GHz mm-wave band was simulated, fabricated, and measured. The measured results show that the minimum coupling level (min|S<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub>|) is as low as −70 dB, and the 20-dB decoupling bandwidth with |S<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub>| < −20 dB is as wide as 39.35%.