Out-of-band improvement of a switchable narrow bandpass filter

This paper deals with the improvement of a switchable narrow‐bandpass planar filter. A first switchable filter, based on the dual‐behavior resonator (DBR) topology, is designed. However, the superposition of the passband and spurious resonance from one state to the other may occur. So, its out‐of‐band behavior is improved through an association with a coupled‐line filter. This results in a hybrid filter with a high rejection close to the passband due to the DBR filter and the elimination of the spurious resonance in the two attenuated bands due to the coupled‐line one. Based on this particular topology, we also realize a switchable filter for which superposition problems are eliminated. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 481–484, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21023