Abstract: A device and a method are provided for improving the operation of ignition devices, in which the parasitic waves causing interference are attenuated by means of a combination of resistors, connected in the primary and/or secondary of the ignition circuit (high voltage circuit of the coil). According to the invention, frequency sensitive resistor cables and a direct or simulated secondary resistance (formed by a small resistance placed in the primary of the ignition circuit) are substituted for the classical secondary resistive ignition cables and/or lumped resistors.Ignition and RFI-radiation can so be optimized by reducing ignition energy to its original level, and by adapting the last to the actual need i.e. varying its value in accordance with engine rpm etc.

Abstract: A low pass filter produced by cable-manufacturing techniques and using a long, distributed capacitance "filter-line" which, when cut into pieces, produces lumped lossy filters. To exhibit appreciable distributed capacitance together with magnetic flux concentration, use is made of special dielectromagnetic materials based on mixtures which synthesize high permittivity, low permeability and high losses.

Abstract: The protection against interference emitted by automobile internal combustion engines or other vehicles is provided by an element for a spark plug or for a distributor, comprising a shield 3, a resistor 4 increasing with the frequency to be filtered and a capacitor 5, selected in such a manner that the RC product is higher than the time constant corresponding to the cut-off frequency.Good reduction of interference is obtained between 10 and 1000 MHz.