Cross-coupled microstrip band reject filters with non-resonating nodes

A new design of cross-coupled band reject filters in microstrip technology is presented. In the proposed model, the source and the load are not directly coupled. Instead, non-resonating nodes (NRNs) are introduced in the network to generate the required number of attenuation poles and modularize the design. Higher order band reject filters are designed by cascading lower-order building blocks with NRNs inserted between them. A fourth order filter is designed, built and measured. Good agreement between theory and measurement is achieved.