A Simple Decoupling Method for Wideband Millimeter-Wave MIMO Magnetoelectric Dipole Antenna Array Using Parasitic Stubs

In this article, a simple decoupling method utilizing parasitic stubs is proposed for the wideband millimeter-wave (mm-wave) multi-input multi-output (MIMO) magnetoelectric (ME) dipole antenna array. Metal stubs are added to the electric dipole patches at the terminal positions. It is found that the coupled current of the adjacent antenna primarily localizes near the metal stubs, exhibiting its strongest amplitude at the stub terminals. Through appropriate adjustment of the metal stub lengths, the coupled current can establish a node with zero amplitude at the antenna’s center. As a result, energy cannot ingress into the receiving port via the coupling slot, resulting in enhanced isolation. To validate this method, a prototype of a $1\times 2$ MIMO ME dipole antenna array is simulated, fabricated, and tested. The measured results demonstrate a wide operating bandwidth of 28.1%, spanning from 25.1 to 33.3 GHz. Throughout the entire passband, isolation exceeds 22 dB, and the maximum isolation reaches 52 dB at 30.1 GHz. Moreover, the proposed decoupling method exhibits versatility, being applicable to multielement arrays and wide-angle beam-scanning phased arrays.