A genetic metamaterial and its application to gain improvement of a patch antenna

A genetic metamaterial, whose periodic but irregular structure is completely designed by the Genetic Algorithm (GA) without a preexisting form, is presented and applied to improve the gain of a patch antenna. This metamaterial is fabricated on a printed circuit board (PCB), and consists of unit cells periodically distributed on the PCB. Each unit cell is gridded into 10 x 10 square pixels, whose dimensions as well as conducting or non-conducting properties are determined by the GA. Four layers of such a genetic metamaterial are placed in front of a rectangular patch antenna. At the working frequency of 3.6 GHz, both the simulation and the measurement results show that the genetic metamaterial layers have greatly improved the gain of the patch antenna over 4.1 dB (from 8.3 to 12.4 dBi), and thus the corresponding aperture efficiency is increased from 38 to 95%; meanwhile, results of an equivalent parameter retrieval show that the GA designed genetic metamaterial possesses the double-negative (DNG, i.e. both the negative permittivity and the negative permeability) characteristics.