Design of a sharp response microstrip lowpass lter using taper loaded and radial stub resonators

This paper proposes a compact microstrip lowpass lter with a wide stopband and a very sharp roll-off. This structure consists of two dual taper-loaded resonators that are connected to the radial stubs. The resonators are described using an LC model, and its Z- and S-parameters are extracted as a function of the LC component. In the proposed lter, cut-off frequency is placed at 1.76 GHz, roll-off rate is higher than 142 dB/GHz, insertion loss is less than 0.42 dB from DC to 1.5 GHz, and rejection is greater than {24 dB from 1.88 to 15.2 GHz. The proposed lter is designed, fabricated, and measured, and the measured values are in good agreement with the EM-simulated results.

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