A novel approach for low mutual coupling and ultra-compact Two Port MIMO antenna development for UWB wireless application

Abstract

In this paper, a novel MIMO antenna operating in the UWB frequency band is presented. The proposed new antenna shape is derived from the conventional circular ring patch antenna having a partial ground plane. An array of three Quad-G Shaped Metamaterial structures was used between the antenna elements of the two-port MIMO antenna to expand the bandwidth in the lower frequency band of UWB application (below 5.567 GHz) and reduce the mutual coupling in such expanded band. The proposed MIMO antenna operates over a bandwidth of 8GHz from 4 GHz to 12 GHz. Over the entire bandwidth, the mutual coupling between antenna elements is less than -19.0 dB with an inter-element separation (sep) of λ/6 mm. The overall optimized dimensions of the proposed antenna are 0.34λ×0.22λ×0.021λ for a free-space wavelength, λ, calculated at 4GHz. The radiation pattern of the proposed MIMO antenna was analyzed using the Combined Results Technique (CRT) integrated into the CST microwave studio. The obtained peak radiation efficiency and gain are 83.0% and 5.57 dB respectively. The MIMO Performance metrics such as envelope correlation coefficient (ECC), diversity gain (DG), channel capacity loss (CCL), Mean Effective Gain (MEG), Total Active reflection Coefficient (TARC), and multiplexing efficiency are evaluated and compared to the standard values. The proposed antenna was compared to other antennas in the literature. It has been found that the key benefit of the present method was observed in achieving the highly miniaturized overall antenna dimension having good MIMO system performance metrics and better radiation characteristics. The proposed antenna was fabricated and measured. The measured and simulated values are found to be in good agreement.