JPS6429009A - Noise filter for high frequency wave - Google Patents

Abstract

PURPOSE:To obtain a noise filter, which is small-sized, lightened in weight, of good mass-productivity and cheap by constituting a filter circuit by using magnetic material with high specific resistance as the dielectric of a capacitor. CONSTITUTION:This noise filter is constituted of the magnetic material 11, which is cylindrical ferrite core and has the high specific resistance of the value of over 1MOMEGA.cm at least, and electrodes 12, 13 and 14, formed on the surface of the magnetic material 11. The electrodes 12, 14 are formed on the outer surface of the magnetic material 11 at interval of a margin (m), and the electrode 13 is formed on the whole of the inner circumferential surface and the side surface of the magnetic material 11. Then, a conductor 15 penetrates the center of the magnetic material 11, and the electrode 13 is connected to the conductor 15, and the electrodes 12, 14 are connected to a metallic case 16, and they are tightly sealed in the case 16. In this constitution, the magnetic material 11 of the high specific resistance acts as the dielectric of the capacitor, and one through-type capacitor is formed respectively between the electrodes 12 and 13 and between 13 and 14. Then, a pi type filter is constituted by combining these plural capacitors and a coil element, consisting of the magnetic material 11 and the conductor 15.