microstrip lowpass filter with sharp roll off and wide stopband using multiple cascaded modified radial stubs resonators

This paper presents a novel microstrip lowpass filter with good performance. a complete detailed theoretical analysis for the proposed filter is given using equivalent circuit models. the proposed filter applying multiple cascaded modified radial stubs resonators provides a sharp cut off frequency response that has a 185 db/ghz roll off rate. also, ushaped attenuators provide a wide stopband about 14fc with more than 20 db rejection. the filter has an insertion loss less than 0.027 db from dc to 1.31 ghz. the proposed filter has a high figure of merit, equal to 32317. the experimental results are in fair agreement with the simulated results.