In this article, a simple model is proposed to compute the effective dielectric constant, resonant frequency, quality factors, input impedance, bandwidth and gain of a coaxial probe fed annular ring patch antenna loaded with several dielectric layers. This model is based on conformal mapping technique, cavity model and single resonant parallel R-L-C circuit. The computed values employing the present model are compared with experimental and simulation results. The present model shows good agreement with experimental and simulation results.

In this paper, a ring patch antenna with 1 GHz of bandwidth and three resonances is designed for the RF energy harvesting application. Two complementary split-ring resonators (CSRR) is etched out from the patch, designed at 6.8 GHz, near feed to enhance the bandwidth from 267 MHz to 1 GHz. Due to the introduction of CSRR, two additional resonances at 6.4 and 7.4 GHz are obtained with gain 5.5 and 0.2 dB respectively. The gains at 6.8 and 7.4 GHz are enhanced to 8.3 and 2 dB respectively by cascaded circular mushroom electromagnetic bandgap structures (EBGs) with circular symmetry designed around the antenna. This ring patch antenna with cascaded EBG is integrated with a rectifier circuit based on voltage doubler topology (rectenna). The results of the rectenna show that, for an input power of 7 dBm to the rectifier circuit, a DC output voltage of 1.2 V with a power conversion efficiency of 40% is achieved.