Artificial Magnetic Conductor Based Improved Radiation Properties of Fractal MIMO Antenna for UWB Applications

A novel artificial magnetic conductor (AMC) structure as a reflector is presented to enhance the gain of a fractal ultrawideband (UWB) multi-input multi-output (MIMO) antenna. Unit cell of proposed AMC structure is achieved through 4 iterations to obtain better characteristics as reflector. An in-phase reflection from 2-16 GHz is achieved by the unit cell. The proposed AMC structure 6 x 6 array and 6 x 12 array are examined with single element and 2 element fractal MIMO antennas, respectively. The fractal MIMO antenna backed with an AMC structure achieved an operating band from 2.2 to 15.8 GHz, and the isolation between the elements is greater than 23 dB. The proposed AMC structure is fabricated, and experimental results are analysed in comparison with simulation ones. An average gain improvement of 6.1 dB is observed by the proposed AMC structure in the operating band. Surface current distributions, EM fields, and radiation patterns are investigated at various frequencies. MIMO performance parameters such as diversity gain, total active reflection coefficient, envelope correlation coefficient, and channel capacity loss characteristics are analyzed in this paper. The fractal MIMO antenna backed with an AMC structure exhibits good diversity performance characteristics with improved radiation properties for UWB applications.