A novel compact microstrip bandstop filter based on complementary split-ring resonators

In this paper, a novel compact microstrip bandstop filter using complimentary split ring resonators (CSRRs) is proposed. The bandstop is produced by an array of CSRRs etched on the center line of a microstrip. This behavior is due to the presence of negative effective permittivity and positive permeability near resonant frequency which prevent the wave propagation. We have achieved controllable resonance frequency, super compact dimension, low insertion losses in the passband and high level of rejection in the stopband with sharp cutoff. Because of the sub-wavelength operation of CSRRs, the electrical size of the filter is very small. Additionally, it can be easily fabricated and compatible with MMIC or PCB technology. The proposed device is believed to be a very promising novel structure of microstrip bandstop filter based on CSRRs.