Mutual Coupling Reduction in Patch Antenna Array Based on EBG Structure for MIMO Applications

Abstract

This paper presents a printed rectangular slot microstrip antenna array of two elements based on an Electromagnetic Band Gap (EBG) structure. The proposed EBG structure is invented to improve the isolation between the radiating elements for multiple-input multiple-output (MIMO) application. Single and two slotted rectangular microstrip antennas are designed on an FR-4 substrate with a dielectric constant (ε_r) of 4.3 and loss tangent (tanδ) of 0.025 with thickness of 1.6 mm. The proposed EBG structure is designed as one planar row of 24 slots. The proposed array performance is tested numerically using Computer Simulation Technology Microwave Studio (CSTMW) of Finite Integration Technique (FIT) formulations. The antenna performance in terms of reflection coefficient (S₁₁), isolation coefficient (S₂₁), radiation patterns, boresight gain and Envelope Correlation Coefficient (ECC) are investigated before and after introducing the EBG structure to identify the significant enhancements. The proposed EBG structure is located between the radiating antenna elements to reduce the mutual coupling of the proposed antenna array. The edge to edge separation distance of the proposed antennas is λ₀/16, where the λ₀ is the free space wavelength at 2.45 GHz. The simulated results show a significant isolation enhancement from –6 dB to –29 dB at the first resonant frequency 2.45 GHz and from –10 dB to –25 dB at the second resonant frequency 5.8 GHz after introducing the EBG structure to the antenna array.