Compact ultra-wideband antenna with sharp band-notched characteristics for WiMax and WLAN

A new design of a compact ultra-wideband antenna with sharp band-notched characteristics is presented. By utilising an interdigital capacitance loading loop resonator, the presented design has very high selectivity and achieves dual notches of the lower WLAN 5.25 GHz and upper WLAN 5.775 GHz bands, while it can still receive signals from the intermediate band between 5.35-5.725 GHz and effectively saves many more useful frequencies. To reject interference of WiMAX 3.5 GHz, the arms of the forked-shaped radiator are folded to form a pair of coupled lines. Based on simulation and measurement, it shows that the proposed antenna can guarantee a wide bandwidth from 3 to 12 GHz with triple independently controllable notched bands.