Design of Microstrip Lowpass Filter Using bend Configuration with Excellent sharpness in Transition Band

摘要

In this letter, a microstrip lowpass filter (LPF) using bend configuration with several excellent features such as a compact size, great roll-off rate and high rejection in the stopband is presented. This structure is composed of a spiral transmission line loaded by several stepped impedance and T-shaped resonators. The cut-off frequency of the proposed filter is equal to 2.73 GHz and the transition band is from 2.73 up to 2.82 GHz with -3 and -20 dB attenuation point, respectively, which represents a very high sharpness in the transition band. To achieve a -40 dB rejection level in the stopband, multiple open stub and T-shaped patches are utilized. An acceptable agreement between EM-simulation and measurement results is observed.