Gain improvement of tunable band-notched UWB antenna using metamaterial lens for high speed wireless communications

摘要

This paper introduces design of UWB antenna with gain improvement using single layer of metamaterial structure. The proposed UWB antenna consists of circular patch with stepped cuts and curvature in ground plane to achieve the desired matched impedance from 3.1 GHz up to 12 GHz. In order to achieve a notched frequency band from 5.7 to 5.9 for interference mitigation with WLAN applications, an omega structure is etched in the radiating patch. Lumped capacitor is inserted in omega structure to tune the notched frequency from 5.7 GHz (WLAN band) to 3.8 GHz (WiMAX band). The gain of UWB antenna is improved by adding single array layer with 3 x 2 inverted L-shaped metamaterial unit cells. The single layer metamaterial can modify the radiation pattern of the UWB antenna by enhancing its gain. This enhancement is due to the negative characteristics of the metamaterial structure which behaves as super lens when placed in front of the antenna as a cover. The realized gain is increased up to 5.5 dB within the achieved frequency range except the frequency band of the notch. The performance of the antenna is confirmed by the measured analysis with good agreement when compared with the simulated ones.