A Differential UWB Quasi-Yagi Antenna with A Reconfigurable Notched Band

Abstract

Abstract A compact differential ultra-wide band (UWB) planar quasi-Yagi antenna is presented in this paper. The proposed antenna consists of a balanced stepped-impedance microstrip-slotline transition structure, a driver dipole and one parasitic strip. A wide differential-mode (DM) impedance bandwidth covering from 3.8 to 9.5 GHz is realized. Meanwhile, a high and wideband common-mode (CM) suppression can be achieved by employing the balanced stepped-impedance microstrip-slotline transition structure. It is noted that the DM passband is independent from the CM response, which can significantly simplify the design procedure. In addition, a reconfigurable sharp DM notched band from 5.6 to 6.7 GHz is generated by adding one pair of quarter-wavelength varactor-loaded short-circuited stubs adjacent to the microstrip line symmetrically. In order to illustrate the effectiveness of the design, two prototypes of the antennas are designed, fabricated, and measured. A good agreement between the simulated and measured results is observed.