1. Introduction Filtering is one of promising techniques to reduce or eliminate unwanted electromagnetic noises. Usually, filters are used to attenuate unwanted frequencies traveling along conductors, and are characterized by attenuation versus frequency curves. Improper use of filters can make emissions or immunity of a 1. Introduction Filtering is one of promising techniques to reduce or eliminate unwanted electromagnetic noises. Usually, filters are used to attenuate unwanted frequencies traveling along conductors, and are characterized by attenuation versus frequency curves. Improper use of filters can make emissions or immunity of a