Investigation on MIMO Antenna for very Low ECC and Isolation Characteristics using FSS and Metal-Wall

Abstract A closely coupled (minimum distance of 0.14 λ 0 ) Multiple Input Multiple Output (MIMO) antenna with high isolation is proposed. The MIMO antenna comprises of two circular-shaped radiating elements, which are fed by two opposite directed microstrip lines. The ground plane consists of modified Z-shaped metallic plane. Two different techniques are explored for improvement of isolation of MIMO antenna. First, a double ring structured frequency selective surface (FSS) is positioned above the antenna. The combination of FSS & antenna structure works with high isolation ( S 21 or S 12 ) (peak isolation of 49 dB) across the entire operating range (3.8 GHz-5.3 GHz). Secondly, a rectangular metallic plate of thickness 0.3 mm is placed vertically between the MIMO antenna, which covers 4 GHz-5.3 GHz bands with high isolation (peak isolation of 49.4 dB). The proposed design consists of the MIMO antenna with both FSS and metallic plate. The proposed structure provides an appreciably high isolation (peak isolation of 59.5 dB) and peak gain of 4 dBi with Envelope Correlation Co-efficient (ECC) lower than 0.004. The proposed antenna having dimension of 40 mm × 40 mm is tremendously suitable for high isolation wireless applications.