An investigation of transmission line switching and frequency shifting in dipole antennas using optically activated silicon switches

With the rapid expansion of wireless communication services such as Bluetooth and Wireless Local Area Network (WLAN), the ability of the antenna in a communications device to cover multiple bands is growing in importance. Using many antennas to cover an ever increasing number of bands is becoming impractical with restrictions imposed by available space and cross-interference. It is in this environment that frequency reconfigurable antennas are becoming a more attractive option. Much work has already been presented on tuneable antennas using varactor diodes, PIN diodes and more recently Micro-Electro-Mechanical Systems (MEMS) devices, but each of these solutions require metal biasing lines that may interfere with the radiation patterns and can suffer from low power handling capabilities. In this study, a novel approach is presented where near infra-red light delivered through glass fibre optic cables is used to activate simple photoconductive switches embedded in a planar dipole antenna. [Continues.]