Effects of superstrate with improved SSRRs on the radiation of microstrip antenna

Both the effective permittivity and the effective permeability of a left-hand medium (LHM) with four cells of surface split square ring resonator (SSSRR), an improved LHM unit cell, is calculated by using transmission/reflection method. Then metamaterial superstrates with different arrange of the SSSRR cells are devised, and their effect on the radiation characteristics of traditional rectangle microstrip patch antenna is quantified numerically. According to the results attained, it is noted that by adding some more layers of the LHM with four SSSRRs, the gain can be further enhanced and the antenna pattern becomes more directive, while the return loss acts in an opposite way with the increase of layers.