Wideband Reflectionless Antipodal Tapered Slot Filtenna With High Out-of-Band Absorption Ratio
Jinlun Li, Haoyan Ma, Kelin Zhang, Shunli Li, Hongxin Zhao, Xiaoxing Yin
Abstract
An antipodal tapered slot antenna (ATSA) with wideband reflectionless filtering characteristic is proposed in this work. The ATSA incorporates a wideband absorptive bandpass filtering network, which consists of a parallel coupled line (CL), a stepped impedance open stub (SIOS), and a resistively terminated T-shaped bandstop filter. This network is designed using the frequency complementary diplexing concept, where in-band input energy is selected by the CL and SIOS and radiated by the ATSA; out-of-band energy is dissipated on the resistor through the bandstop filter. The SIOS also enhances out-of-band absorption and suppression by introducing additional gain nulls. A prototype was fabricated and measured, yielding a 3 dB gain bandwidth from 3.2 to 6.8 GHz and a wide impedance bandwidth from dc to 11.8 GHz with an out-of-band absorptive ratio greater than 80%. In addition, the realized gain exhibits a sharp bandpass radiation characteristic with measured out-of-band suppression higher than 25 dB in the lower stopband and 16 dB in the upper stopband.