ABSTRACT In this brief, a planar mu negative decoupling medium (μNDM) is proposed for suppressing the strong coupling between tightly arranged 1×2 MIMO antenna. The dielectric is composed of a double‐period metal rectangular loop resonator (46.6 mm × 26.1 mm × 1.5 mm) array etched on the substrate. For the original antenna array (OAA), the μNDM on both sides is more decoupled than the μNDM in the middle and top, and has less negative impact on the OAA. The experimental results show that the scheme can achieve an average port isolation improvement of more than 23.5 dB (at least 19.2 dB, up to 31.6 dB) in the working frequency band of 3.3 ~ 3.8 GHz (5 G NR n78), and the peak gain of the antenna after decoupling can reach 6.44 dBi. More importantly, the impedance bandwidth has been extended to 2.83–4.17 GHz. On the additional impedance bandwidth, the port isolation improvement is more than 11.9 dB on average. The decoupled array shows a low envelope correlation coefficient (ECC < 0.001) and excellent channel capacity (the peak value of CC can reach 11.39 bps/Hz) in the whole band of interest. Compared with the traditional metasurface, which usually only guarantees a single performance index, this idea can not only achieve wide decoupling bandwidth and deep decoupling strength simultaneously, but also significantly broaden the impedance bandwidth, which has a wide application prospect.
Li et al. (Wed,) studied this question.