A compact quad-band bandstop filter using square spiral resonators based on folded stepped impedance resonator

摘要

In this letter, we propose the simulation, design and fabrication of the microstip quad-band bandstop filter (QBBSF) with Square Spiral Resonators (SSR). The basic cell of the structure consists of a folded stepped impedance microstrip transmission line. The center frequency of the filter is 1.12 GHz, 3.61 GHz, 6.20 GHz and 9.81GHz with the bandwidth of 1.13 GHz, 1.25 GHz, 1.12 GHz and 3.01GHz, respectively. The experimental results are closely matched with the simulated results.