Design of compact dual‐ and tri‐band bandpass filters using λ/4 and λ/2 resonators

Abstract This article presents a novel approach for designing dual‐ and tri‐band bandpass filters with independently controlled center frequencies and bandwidths. λ/4 and λ/2 resonators are used to obtain dual‐ and tri‐band responses. λ/4 resonators are designed to operate at the lower passband(s) and λ/2 resonators are designed to operate at the higher passband. The bandwidth of each passband can be tuned independently by adjusting the coupling gap. To verify the presented concept, two experimental examples of filters have been designed and fabricated and good agreements are shown between the simulation and the measurement. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 638–641, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24111