Abstract: A new structure for electro-magnetic signal filters is described. The structure of the invention incorporates ideal time lag elements having delay values selected to match an arbitrarily selected set of frequencies matched to a desired frequency response and connected in a cascade array by second filter elements which null the frequency filtered by the preceding array, the output of which is summed to provide a composite output with the desired frequency response. The resultant filters are easily implemented in conventional hardware and the techniques may be applied to a broad range of the electro-magnetic spectrum by the choice of appropriate components.