Notch Implementation in Planar Band Stop Filter using Step Impedance Resonator Approach

This paper demonstrates the implementation of pass band notch in a band stop filter. The structure is constructed by incorporating stepped impedance resonator topology in dual behavior resonator. Dual behavior resonator brings two attenuation zeros in erstwhile band-stop characteristics. An addition of coupled quarter-wavelength line at one end of the port brings notch characteristics. Highly selective pass band notch has been demonstrated and measured results show band pass notch characteristics having return loss better than 10 dB in 5% bandwidth.