Design of Wide-Band Semi-Lumped Bandpass Filters Using Open Split Ring Resonators

Open split ring resonators (OSRRs) are used in this letter to design wide-band semi-lumped bandpass filters. OSRRs work as lumped $LC$ series elements due to their small electrical size and can be then used as building blocks of reduced size band pass filters. The values of the capacitance, $C$, and inductance, $L$, of the OSRR are controlled by adjusting the geometrical parameters of the coupled open rings. In our design, the OSRRs are connected through quarter-wave lines which act as inverters. The impedance of these inverters have been conveniently calculated to achieve the filter specifications. Finally bending and/or meandering techniques have been applied so as to obtain highly compact designs. Experimental verification is provided and good agreement has been found between electromagnetic simulations and measurements.