Novel Compact Narrow-band Microstrip Dual-mode Resonator Filters for 3G Telecommunication Systems

Novel compact microwave bandpass filter configurations based on the dual-mode microstrip square loop resonators are proposed. Two bandpass prototypes operating in the UMTS frequency range have been fabricated and measured: a 4-poles and a 5-poles dual-mode filters with a bandwidth of 3 %. These filters exhibit significant dimension reduction without any appreciable decrease of performance thus making themselves very attractive for nano- and pico- cellular base stations in 3G communication services.