AbstractIn this letter, simple and effective design of dual‐band bandpass and bandstop filters using microstrip open‐loop resonators is proposed.The dual‐band bandpass and bandstop filters developed in this letter exhibit dual operating frequencies that are not integral multiples of each other and are realized using a simple method rather than using the extensive method of extracting coupling coefficient matrix for designing dual‐band filters. Parametric analysis is performed on the proposed microstrip structures to determine the optimum dimensions of the dual‐band filters. Both simulation and measured results are presented in this letter, and good agreement is obtained between the results. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:168–171, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26469