Design of an ultra wide band (UWB) filter using tightly, coupled lines in micro strip medium suitable for UWB communications has been presented in this paper. Coupled lines with centrally loaded open circuited stubs have been appropriately chosen to locate the two attenuation poles, close to either side of the desired pass band. Experimental results of a 3.1-5.3 GHz filter designed using the present method have been verified against the results obtained from circuit model. (c) 2006 Wiley Periodicals. Inc.