Research On Broadband EMI Suppression Material

The aim of this dissertation was to provide theoretical and experimental evidence for developing new type broadband EMI suppression material. Aimed at the problem of poor knowledge on the relationship between suppression mechanism and material's characteristic and poor performance of traditional ferrite in high frequency band, following parts would be analyzed in detail.At first, according to the practical application, different model of transmission line were used to analyze the suppression mechanism. Then, the relationship between suppression effect and material's characteristic was further researched. After that, the result showed that suppression effect of magnetic core had the identical variety with imaginary permeability and transmission loss of magnetic sheet enhances with bigger imaginary permeability, longer length, more thick.And then, with the combination of theory of Electromagnetism and Ferromagnetism, the influence of magnetic parameters and morpha on spectrum of magnetic permeability was investigated. The result of different magnetic parameters with different permeability, global powder with good performance in low frequency band and flat powder with excellent performance in high frequency band were gotten. Afterward, after the analysis of limit of application of soft-magnetic alloy, good performance soft-magnetic alloy composite material was successfully prepared through the reasonable process constituted according to suppression mechanism and theory of permeability.In succession, the suppression effect and permeability of different combination of magnetic core were investigated. Then the result showed that combination of magnetic core had different suppression effect. Though the combination of magnetic core, application would be expand.At last, according to suppression mechanism and theory of permeability, how to choose and prepare suppression material were researched for the first time...