Design of Ultra-Wideband Tapered Slot Antenna Using Novel Feeding Structure

This paper proposes a printed ultra-wideband (UWB) tapered-slot antenna (TSA) using a novel feeding structure. It consists of two symmetrical radiating flares printed on the top-side of a dielectric substrate. The feeding structure employs novel microstrip-to-slot transformers with via, circular stubs, and circular slots to realize UWB out-of-phase power divider features, which serves as a differential-feed scheme for the two radiating flares. The final design of the proposed TSA with dimensions of 150 mm ×98 mm ($0.58\lambda_{min} \times 0.38\lambda_{min}$, where $\lambda_{min}$ is the wavelength at the lowest operational frequency) is fabricated and measured. Both simulation and measurement result in an impedance matching bandwidth of 160% (1.19 – 11 GHz). Moreover, across its impedance matching bandwidth, the antenna prototype achieves a good end-fire radiation with the peak gain of 10.2 dBi, highly symmetric pattern, small cross-polarization level, and high front-to-back ratio.