Abstrakt

In this article, an attractive multimodal substrate integrated waveguide (SIW) based methodology is presented for the characterization of magnetic materials in the broadband microwave frequency. The proposed approach employs a modified feed under-coupled SIW cavity instead of conventional feed over-coupled multiple SIW cavities; it uses the modified closedform expression, developed from the first principle to consider the effect of finite sample dimensions, and mode-specific sinusoidal field variations, which were not considered before for magnetic testing using the over-coupled SIW cavity and conventional formulations. The metallic cavity borne approximations i.e., very small frequency shift for the imaginary part calculation, and very high Q-factor for the real permeability estimation are also relaxed in the modified formulations. The proposed technique is numerically verified using the full-wave electromagnetic (EM) simulator for several dispersive and nondispersive standard samples; thereafter, it is validated for the estimation of complex permeability of synthesized dispersive magnetic composites. It can characterize the dispersive magnetic composites, where the permeability value varies from paramagnetic to diamagnetic range, with improved accuracy than that of the conventional cavity perturbation approach. The modified formulation provides 34% and 12% better estimation of loss tangent and real permeability, respectively, as compared with the conventional technique. The uncertainty analysis for change in sample volume, sample misalignment, and the possible air gap is also carried out in detail. The proposed scheme typically provides more than 92% and 84% accuracy in the measured values of real permeability and loss tangent data, respectively, for various synthesized magnetic samples in broadband of microwave frequency (10–22 GHz).

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