Wideband, compact microstrip band stop filter for triband operations

Tri-band BSF working at C, Ku and K band has been developed using a single topology. The designed 3-in-1 filter posses compactness, wider bandwidth, and low insertion loss. The proposed topology is constructed using spurline filter at the output connected with a section of anti-coupled lines. The filter with the presented approach can be used to shift the frequency at the desired location by optimizing the line lengths. The measured return loss is better than 2 dB for all the three bands. There is a good agreement between the simulated and experimental results.