AbstractA compact open loop resonator microstrip low pass filter is modeled. To optimize the performances of the filter, electromagnetic simulation is used to tune the dimensions of proposed prototype. Cascading of open loop resonator provides a very sharp cut off and wide stop band with minimum insertion loss. The filter is simulated with an equivalent circuit model and it is found to be in good agreement with the structure model response. The structure provides a near ideal response. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2983–2986, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23817