AbstractIn this paper, a bandpass filter using stepped‐impedance coaxial resonators is presented. Each stepped‐impedance resonator (SIR) is composed of ceramic/material to ensure temperature stability of the resonant frequency; one has a positive temperature coefficient of resonant frequency (τf), and the other has a negative τf. A capacitively coupled three‐pole bandpass filter is designed and fabricated to have a center frequency of 915 MHz and a passband bandwidth of 20 MHz. The improved temperature stability of this filter is demonstrated by experimental results. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 508–510, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10651