Design of a High Order Dual Band MIMO Antenna with Improved Isolation and Gain for Wireless Communications

Abstract

An 8-elements dual band multiple-input multiple-output (MIMO) antenna is proposed in this article. The single element antenna consists of a defected ground structure (DGS) to obtain the first resonance at 2.4 GHz (Wi-Fi) and inset fed patch is responsible for second resonance at 3.6 GHz (Wi-MAX). As the single antenna is extended for 8-elements MIMO arrangement in a compact layout, the |S11| deteriorates which improved by engraving additional I-shaped DGS slots that enhances the impedance matching at the antenna ports. Due to closely placed antenna elements the mutual coupling at the resonant bands is poor. Hence, T- shaped stubs are introduced to achieve reduced mutual coupling between the antennas which effectively improves isolation characteristics of individual antenna elements beyond − 20 dB. A dual band Artificial Magnetic Conductor (AMC) is designed and placed below the MIMO antenna at a certain distance to enhance the gain at both the bands without perturbing the scattering parameters. The gain is improved from − 2.7 to 3.5 dB at the first resonance and from 1.7 to 3.85 dB at the second resonance. The diversity performances of MIMO are calculated in terms of Envelop Correlation Coefficient, Diversity Gain, Mean Effective Gain, Channel Capacity Loss, Total Active Reflection Coefficient, and Multiplexing Efficiency which confirm that the proposed MIMO antenna is a very potential candidate for multifunctional high speed wireless communication systems. The composite MIMO antenna with AMC is fabricated, and the antenna characteristics are measured which comply with the simulated results.