A new type of microstrip band-stop filter using spurline

In this paper, A wide bandwidth micro-strip band-stop filter (BSF) is presented. This filter combines two traditional BSFs: stepped impedance resonator and spuline. A micro-strip line is used as the main line, then spurline is used to realize filtering some frequency. For efficiently reduce the size of the filter, the spurline was designed as SIR structure. 1/4 wavelength SIR resonator can be equivalent as the capacitor and inductance on the basic principle of band-stop filter. Due to the inherently compact characteristics of the spurline, the proposed filter shows a better rejection performance than open-stub. From 3.6 GHz to 4.4 GHz, the proposed filter has a better rejection with S21 is less than 20dB and the maximum rejection level of 80dB. The stop bandwidth is 20% and its spurious stop band is high than 13 GHz, more than 3 times as high as the center frequency, the SWR is less than 1.5.