Wideband microstrip band stop filters realization with interdigital topologies

This article proposes novel wide band stop filter topologies at C-band with simpler implementation in microstrip. The introduction interdigital resonator along with stepped impedance resonator concept is utilized for the placement of transmission zeros to achieve wideband performances. This article demonstrates fractional bandwidth of > 80% with steep skirt rate. This topology is modified further to achieve improved out of band performance. The parallel coupled section for input and output signal coupling results in improved out of band performances. The measured 3-dB bandwidth is from 4 to 10 GHz and transmission loss below 0.55 dB is achieved for both the topologies. Close analogies between simulated and measured results is obtained which are detailed in this article. The presented topologies are simpler and novel achieving the desired performances without vias.