AbstractA dual‐mode bandpass filter (BPF) using microstrip patch resonator is proposed. Open‐stubs are added on the feed‐lines to suppress the spurious response and improve the stopband rejection effectively with little increase in circuit size. Furthermore, a reduced‐size dual‐mode BPF with spurious response suppression using microstrip slotted‐patch resonator is successfully designed. The simulated and measured results are presented and both are in good agreement. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 556–558, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22190