Design and Time-domain Analysis of Compact Multi-band-notched Uwb Antennas with Ebg Structures

Four ultra-wideband (UWB) antennas are proposed: one referenced antenna without notch and three novel antennas with one, two and three notched bands, respectively. The UWB referenced antenna consists of a beveled rectangular metal patch, a 50 Ω microstrip line and a defective ground plane. Then, by utilizing one, two and three electromagnetic band-gap (EBG) structures on the UWB antenna, the antennas present one, two and three notchedband responses, respectively. The frequency domain characteristics including VSWR, transfer coefficient S21, radiation patterns and group delay are investigated. It is found that the EBG design approach is a good candidate for frequency rejection at the certain frequencies, owing to high performance of notch design and the notched-band bandwidth control abilities. Meanwhile, these abilities also enable less useful frequencies rejected. The design examples exhibit good bandrejected characteristics in the WiMAX/WLAN interference bands (3.4, 5.2 and 5.8-GHz bands). Moreover, good time-domain characteristics of the antennas are checked based on group delay, waveform response, correlation coefficient and pulse width stretch ratio (SR).