TRIBAND FILTER WITH HIGH DESIGN FLEXIBILITY AND WIDE STOPBAND USING DGS AND SHORTED STUB-LOADED RESONATOR

摘要

In this article, a novel triband bandpass filter with high design flexibility and wide stopband is designed by combining a shorted stub-loaded resonator and two cross-coupled DGS (defected ground structure) resonators [two RF (radio frequency) passages] with the same feeding structure. The three passbands can be flexibly designed not only because there is no cross-coupling between the two passages but also because the harmonic passband can be easily eliminated just by embedding the feeding structure with open-circuited stubs, while the performance of the three passbands remains the same. What's more, there are two transmission zeros beside each passband. A prototype filter with three passbands centered at 1.57, 3.45, and 5.28 GHz is designed and fabricated, and it behaves a wide upper stopband to about 9.6 GHz with rejection better than 20 dB. (C) 2015 Wiley Periodicals, Inc.