7th order harmonic suppression and wide rejection band using CSRR backed BSF

Abstract

To obtain the high rejection level for undesired band from a microstrip band pass filter, a complimentary split ring resonator (CSRR) backed bandstop filter (BSF) has been used at the input of bandpass filter. This arrangement gives harmonic suppression for symmetric passband response with a minimum area of filter. In this paper, we have investigated role of CSRR backed BSF for suppression of higher order harmonics along with wider rejection bandwidth. Through better optimization, we report a filter of area 154.242 × 30 mm², which consists of BSF/CSRR at both input and output ports. Simulation results demonstrate the rejection level of 18.94 dB for the fifth order harmonic with maximum rejection of 115 dB in stop band. Better rejection upto the seventh order and wide rejection bandwidth of 4.6 GHz (1.7 – 6.3 GHz) have been obtained experimentally.