Miniaturized Tapered Slot Antenna With Signal Rejection in 5–6-GHz Band Using a Balun

A miniaturized elliptically tapered slot antenna fed by a novel balun is proposed for directional ultrawideband (UWB) applications. The feeding configuration consists of a stepped microstrip line and a folded slotline connected with a circular slot. An arc-shaped parasitic strip is printed inside the circular slot. This design achieves the minimization of the physical size and the capability of signal rejection at 5-6 GHz with significant gain suppression of 15 dB. Both simulated and measured results confirm the advantage of the design in reducing the size of the antenna while maintaining the UWB performance with band-notched function.