Recently electronic equipments are digitalized and those operating frequencies are getting higher. It is necessary to reduce higher harmonic noise which is scattered from digitalized equipments. The size of electronic equipments is getting smaller and smaller. It is required to manufacture EMC devices which have maximum impedance at higher frequency region with smaller size and reduced cost. We will introduce a novel structured choke coil in this paper.Design concepts are as follows.①Applying a drum core instead of a troidal core, in order to apply an automatic wiring system.②Applying a pair of drum and cap core consequently forming a closed magnetic circuit, in order to make the coil possess the electric properties no less than those of a troidal coil.③Applying a novel structure electrode, in order to reduce the number of parts and to make the assembly process simple.We have succeeded in prod 4532 size and 3225 size of choke coils with smaller height compared to our former ones. Those coils have maximum impedance at the frequency range of 100 MHz or higher and coupling coefficients of 0.99 or more.
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