AbstractDesign of a compact broadband filter using tightly coupled line sections in defected (A slot is cut in the ground) microstrip medium operating from 3.1–6.8 GHz has been reported in this article. Filter has been designed and analyzed using an equivalent circuit model based on even and odd mode parameters of coupled line sections. The proposed filter has attenuation poles on either side of the pass band resulting in improved selectivity. This filter features spurious‐free response up to third harmonic frequency. Experimental results of the filter have been validated against the analytical and full wave simulations. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:184–187, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25676