Electrically Small Dual-Band Reconfigurable Complementary Split-Ring Resonator (CSRR)-Loaded Eighth-Mode Substrate Integrated Waveguide (EMSIW) Antenna

In this paper, we propose a novel electrically small dual-band reconfigurable antenna. By using a compact eighth-mode substrate integrated waveguide (EMSIW) structure, we designed a compact antenna. This antenna is capable of dual-band operation by additionally loading an electrically small complementary split-ring resonator (CSRR) structure. The EMSIW and CSRR structures are designed for satisfactory operations at bandwidths of 1.575 GHz [global positioning system (GPS)] and 2.4 GHz [wireless local area network (WLAN)], respectively. We load the CSRR with a varactor diode to achieve a narrow bandwidth and to enable the resonant frequency to continuously vary from 2.4 GHz to 2.5 GHz. Thus, we realize a channel selection function, which is used according to WLAN standards. Irrespective of the variation in the varactor diode voltage, the resonant frequency of the EMSIW is not varied, such that the antenna maintains a constant frequency at the GPS bandwidth even at different voltages. Consequently, as the DC bias voltage varies from 11.4 V to 30 V, the resonant frequency at the WLAN bandwidth continuously varies between 2.38 GHz and 2.5 GHz. We observe that the simulated and measured s-parameter values and radiation patterns are in good agreement with each other.