Modified Split-Ring Resonator for Microstrip Dual-Band Notch Filter

In this paper, a compact microstrip bandstop filter (BSF) with two-notched bands is presented. The dual-band notch filter uses a version of the open interconnected split ring resonator (OISRR), a cell that behaves as a shunt series LC resonant circuit connected in parallel to a microstrip line, thus creating a notch band. The second notched band is generated at a frequency above the first one by adding an open ring with a radius lower than the two open rings of the OISRR. The proposed novel 3OISRR cell has the advantages of introducing two-notched bands without increasing the circuit size while maintaining the ability for the adjustment of the resonant frequencies. The experimental results have confirmed the electromagnetic simulations. Good performance is obtained in the stop-bands and the pass-bands.