Compact UWB antenna with sharp band-notched characteristics and controllable notched bandwidth

A compact Ultra-Wide Band (UWB) antenna with sharp band-notched characteristic and controllable notched bandwidth is presented. The band-rejected structure is realized by adding two half wavelength U-shape Stepped Impedance Resonators (SIR) around the feed-line. The two U-shaped resonators with different placement modes couple together to form a sharp band-rejection. A good impedance matching is obtained in 3.1-10.6 GHz frequency range(|S₁₁|<;-10 dB), except the lower WLAN band of 5.15-5.35 GHz (|S₁₁| >;-5 dB). The ratio of -5dB notched bandwidth to -10dB notched bandwidth is 0.73. Moreover, the band-notched bandwidth can be easily controlled by adjusting the gap between the resonators and the feed-line.