A miniaturized microstrip antenna with tunable double band-notched characteristics for UWB applications.

This paper proposes the step-by-step design procedure for obtaining independent dual band-notch performance, which provides a valuable method for designing tunable dual band-notched UWB antenna. The proposed antenna consists of the semicircle ring-like radiating patch with an elliptical-shaped slot and double split ring resonators on the top surface of the substrate and defected ground structure (DGS) on the bottom surface of the substrate. The operating frequencies ranged from 1.3 to 11.6 GHz (S11 < - 10 dB). By loading varactor diodes at the gap of the resonators structure and changing the varactor diode's reverse bias voltage(0-30 V), a wider band-notched tuning range from 2.47-4.19 to 4.32-5.96 GHz can be achieved, which covers the whole WiMAX band and WLAN band. The experimental results agree well with the simulated results. The notched gain at notched frequency points is about - 5.3 dBi and - 5 dBi, demonstrating that the narrow-band interference signal could be efficiently suppressed. The security of UWB communication systems can be further enhanced. Meanwhile, the selection of varactor diode and DC bias circuit are fully considered. Hence, the accuracy of the experiment results and antenna operating performance have been improved. Furthermore, the proposed antenna only has an electrical size of 0.26λ*0.19λ at 1.3 GHz. Compared to the related reported antennas, the proposed antenna has achieved a simpler structure, low profile, compact size, tunable dual band-notched characteristics, extensive independent tunable range, and good band-notched performance simultaneously, to the best of our knowledge. The proposed antenna is believed to have a valuable prospect in UWB communication, Wireless Body Area Network, Industry Science Medicine, mobile communication applications, etc.