Configuration of a stepped impedance bandpass filter

This paper describes the design of a compact stripline ceramic filter, using short-circuit stepped-impedance resonators (SIRs) to enhance the harmonic stop-band response. Moreover, this filter has a very small size of 3.6 mm x 3.0 mm x 0.5 mm and a low insertion loss of 0. 6 dB in the passband. The filter's response, with a design center frequency of 2390 MHz and 3-dB bandwidth at 250 MHz (10.4%), shows an increase in the first harmonic frequency to 9004 MHz. At three times the fundamental passband frequency (7160 MHz), stop-band attenuation is better than -40 dB. The results demonstrate the usefulness of SIRs for improving the stopband performance of bandpass filters. (C) 2003 Wiley Periodicals, Inc.