A compact high selectivity dual-band bandstop filter using bent L-resonators

A compact high selectivity dual-band bandstop filter is presented. Analyzed by equivalent circuits of coupled-line open results, a method to design a bandstop filter with high selectivity in compact size is achieved. Coupling between two L-resonator is employed to improve the selectivity of the bandstop filter. Using the proposed method, a dual-band bandstop filter with two different pairs of bent L-resonators is achieved. Frequency and bandwidth of the two stop bands can be controlled independently. There are two transmission zeros in each stop band and two rejection zeros at the edge of each stop band. A laboratory model has been realized and measured. Measured results agree well with simulations.