Circular Patch MIMO Antenna with Novel Decoupling Structure

A two-port circular patch antenna with a novel de-coupling structure for multiple-input-multiple-output (MIMO) application is proposed. The slim metal plates and the metallic screws are utilized to construct a pair of series resonators, which provide a high port isolation for the antenna. Owing to this proposed decoupling structure, only one radiating patch is needed and a compact dimension of $\pi\times(0.25\lambda_{0})^{2}\times 0.06)\lambda_{0}$ is achieved. The measured -10 dB impedance bandwidth is 3.21-3.52 GHz (9.2%). A measured port isolation better than 18.6 dB is realized in the operating band and the peak value achieves 44.1 dB. Measured efficiency is higher than 83 % and peak gain is about 6.5 dBi. Finally, a three-port antenna based on the same principle is proposed. Overall, the proposed two antennas with a compact structure, high port isolation and good radiation performance are suitable for MIMO application.