Planar elliptic function lowpass filter with sharp roll-off and wide stopband

Abstract

A compact planar elliptic function lowpass filter with sharp roll-off at 20 dB attenuation level and wide stopband using microstrip stepped-impedance polygonal patch resonators is developed and investigated. Electromagnetic simulation is used to optimize the performance of the filter. The filter using cascaded multiple patch resonators provides a very sharp attenuation near cutoff frequency with a high stopband suppression level. The rejection bandwidth is enhanced by introducing additional transmission zeroes and the results are validated by the experiment. The filter has a compact size of 17.6 mm × 12.2 mm. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:133–136, 2016