A harmonics suppressed microstrip cell for integrated applications

In this paper, a very compact size microstrip suppressing cell is presented. The proposed suppressing cell consists of symmetric modified semicircular patches as main resonator and stepped impedance lines. The main resonator creates a lowpass region and the stepped impedance units provide a wide stopband by creating the transmission zeros in the higher frequency range. So it can be considered as a very miniaturized lowpass filter. The proposed suppressing cell has too many advantages like low insertion loss in the passband. The designed layout has been fabricated and tested. The measured results highlighted the efficiency of the filter and have a good agreement with the simulated results. The −3 dB cut-off frequency is located at 3.8 GHz. The rejection band is from 4.47 to 20 GHz.