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.