Design and Analysis of Compact Circular Monopole Antenna with Tunable Band-Notch Characteristics using EBG Structure.

This work proposes a small circular monopole antenna with reconfigurable dual bandnotch characteristics designed for ultrawideband (UWB) applications. To provide tunable bandnotched characteristics, varactors are stacked in two via fractal (TVF) and mushroom electromagnetic band gap (EBG) structures. The first varactor diode is in the TVF EBG tuning band notch frequency for the WiMAX band (2.8-3.5 GHz). The second varactor diode is situated at the mushroom EBG tuning band notch frequency for the satellite downlink communication (5.9-7.9 GHz) X band. WiMAX and the X-notched band are achieved by varying the tuning of the varactors. Band notch characteristics is constantly reconfigured by adjusting reverse bias voltage across the varactors. The antenna structure is fabricated on FR4 substrate with a size of 24 × 24 mm2 which provides a size reduction of more than 25% with respect to recent literature. Proposed antenna give a large bandwidth (S11< -10 dB) from 2.8 to 12.0 GHz, excluding notched bands. The band notch frequency is continually adjusted from 2.8-3.5 GHz, and 6.0-7.9 GHz by adjusting the capacitance of the varactor diode from 0.487 to 2.35 pF. The simulated and measured results indicate that the proposed antenna is a good candidate. [ABSTRACT FROM AUTHOR]