Dual-Band Bandstop Filter Using Modified Stepped-Impedance Hairpin Resonators

In this paper, a dual-band band stop filter is designed based on a modified stepped impedance hairpin resonator in which, two open stubs are embedded in the structure. There are two transmission zeros in each one of the stop bands. The center frequencies of the stop bands are placed at 2 and 5.92 GHz and their widths are 0.94 and 0.55 GHz, respectively. These stop bands can be adjusted by changing the dimensions of the embedded open stubs. This filter is then transferred to another substrate, fabricated and measured and the results for the two substrates are compared.