A novel reconfigurable band-notched ultra-wideband slot antenna for cognitive radio systems

A novel printed ultra-wideband(UWB) slot antenna with reconfigurable band-notched characteristics for cognitive radio(CR) applications is presented. An improved rectangular monopole antenna is used as the basic model and a tangential rectangular floor is used to realize the ultra-wideband characteristics of 2.9～12 GHz. The band-notched function is achieved by etching one symmetric folded slot which consists of an inverted U-shaped slot and H-shaped slot on the modified rectangular radiation patch. By switching the pin-diodes to change the shape and effective length of the folded slot, the reconfigurable function is achieved. The antenna is compact and easy to process, and has potential application in CR system. Simulated and measured results obtained for the antenna show that it exhibits good radiation behavior and also has three reconfigurable frequency band-notched functions in the range of WiMAX(3.4～3.9 GHz), WLAN(4.6～6.0 GHz) and downlink of X-band satellite communication(6.5～8.2 GHz).