Compact microstrip pseudo-interdigital stepped impedance bandpass filters with improved stopband performance

In this paper we present design of a compact microstrip pseudo-interdigital stepped impedance bandpass filter with improved stopband performance. Stepped-impedance resonators are used to maximise the ratio between higher order and fundamental resonances. The improved stopband performance is realized using additional spur line and open-stub sections used for creation of transmission zeros. Total size of the filter is 30.1times7.2 mm. The stopband extension up to 5.7f
₀
has been achieved.