QPSO-optimized gain-enhanced Koch fractal antenna using NZIM superstrate for satellite and air-borne application

The proposed work presents Koch fractal antenna, with feed optimization using quantum particle swarm optimization (QPSO), and near-zero-index material (NZIM) superstrate to enhance gain. The gain enhancement achieved here uses the unique property of NZIM to collimate divergent broadside radiations emanating from planar array patch antenna. The metamaterial unit cell, called the electric field-coupled resonator designed as NZIM, is configured into a 2 × 2-array structure and used as a double-layer superstrate. The distances from the patch to the superstrate and between the adjacent superstrate layers are optimized for maximum gain using QPSO. The Koch fractal used in conjunction with the proposed NZIM results in dual-band and wideband operation with a significant gain enhancement achieved in the first band and moderate enhancement in the second band, with a large inter-band separation that minimizes co-channel interference.