Compact dualband bandpass filter with two transmission zeros using dual-mode microstrip resonator and tapped-line geometry

In this article, the dualband bandpass filters (BPFs) using dual-mode resonator are designed and implemented. Also, the J-inverter is investigated as function of the impedance and the electrical length of the open-stub in the dual-mode λg/2 microstrip resonator. Especially, the dualband BPFs using dual-mode resonator are realized by the stepped impedance resonator (SIR) structure and have good out-of-band performance as the inverter is alternating by the coupling structure and tapped-line geometry. The first transmission zero of the dualband BPFs is made by the dual-mode resonator and the second transmission zero is defined by the open-stub of the tapped-line geometry as a function of J-inverter. The dualband BPF using dual-mode resonator with two transmission zeros shows the insertion losses of 1.92 and 1.71 dB at the center frequency of 2.42 and 5.65 GHz, respectively. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:108–111, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25627