Systematic Analysis and Engineering of Absorbing Materials Containing Magnetic Inclusions for EMC Applications


A methodology to efficiently design novel products based on magneto-dielectric materials containing ferrite or magnetic alloy inclusions is presented. The engineered materials should provide desirable frequency responses to satisfy requirements of electromagnetic compatibility/immunity over RF and microwave bands. The methodology uses an analytical model of a composite magneto-dielectric material with both frequency-dependent permittivity and permeability. The Bruggeman asymmetric rule for effective permeability of a composite is modified to take into account demagnetization factors of inclusions, and is shown to be applicable to platelet magnetic inclusions. Complex permittivity and permeability are extracted from the transmission-line measurements. A novel accurate and efficient curve-fitting procedure has been developed for approximating frequency dependencies of both permittivity and permeability of magneto-dielectric materials by series of Debye-like frequency terms, which is important for wideband full-wave numerical time-domain simulations. Results of numerical simulations for a few structures containing magneto-dielectric sheet materials and their experimental validation are presented.


Electrical and Computer Engineering

Research Center/Lab(s)

Electromagnetic Compatibility (EMC) Laboratory

Keywords and Phrases

Absorbing Materials; Absorbing Media; Analytical Model; Causality; Complex Permittivity; Demagnetization Factors; Dielectric Sheets; Effective Permeability; Engineered Materials; Experimental Validations; Frequency Dependencies; Frequency-Dependent; Magnetic Alloy; Magnetic Inclusions; Microstrips; Microwave Bands; Numerical Simulation; Systematic Analysis; Time-Domain Simulations; Transmission Line Measurements; Wide-Band; Bandpass Filters; Composite Materials; Computer Simulation; Curve Fitting; Demagnetization; Electric Lines; Electromagnetic Compatibility; Electromagnetic Wave Absorption; Electromagnetism; Ferrite; Ferrites; Frequency Response; Gyrators; Magnetic Materials; Magnetos; Mathematical Models; Microstrip Lines; Permittivity; Time Domain Analysis; Transmission Line Theory; Dielectric Materials; Absorbing Media; Causality; Composite Material; Microstrip Line; Transmission Line Measurements

International Standard Serial Number (ISSN)

0018-9464; 1941-0069

Document Type

Article - Journal

Document Version


File Type





© 2011 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

01 Feb 2011