Methods for Permittivity, Permeability, and Loss Measurements of Polymer Composite Magneto-dielectric Laminates
Magnetics Society and co-host IEEE Magnetics Society Richmond Chapter
Dr. Allen Horn III
Hosted by Prof. Vincent G. Harris (Northeastern University)
Co-hosted by Prof. Radhika Barua (Virginia Commonwealth University)
Please Join us on Tuesday, November 17th, at 4 pm for the November installment of the 2020-2021 Boston’s IEEE Magnetics Society!
Due to the COVID-19 situation we will be meeting via zoom/WebEx. Zoom/WebEx link and registration info (registration is free) will be posted to our website one week before the talk. See below for more details.
Allen F. Horn III, Research Fellow
Christopher J. Caisse, R&D Engineer
Patricia A. LaFrance, Sr. Engineering Assistant
Karl E. Sprentall, Business Development Manager
Rogers Corporation, Advanced Connectivity Solutions, Lurie R&D Center, Rogers, CT USA
It has been well known for more than 50 years to use high dielectric constant copper clad laminates to reduce the size of wavelength dependent microstrip structures such as patch antennas. In the general case, the material’s impedance is (√(μ_R/ε_R ))x(√(μ_0/ε_0 )) where μ_R and ε_R are the relative permeability and permittivity, respectively, and the subscript 0 values are those of free space. The miniaturization factor (by which the material decreases the wavelength of an EM signal) is √(μ_R ε_R ). While all-natural solid materials exhibit an ε_R value > 1, most materials are non-magnetic, with a μ_R = 1.0. Thus, the high dielectric constant results in a material impedance significantly lower than free-space and a reduction in both bandwidth and antenna efficiency of microstrip patch antennas.
A recently developed PTFE – ferrite powder composite laminate exhibits μ_R~ ε_R~ 6 and low electrical and magnetic loss values at frequencies up to 500 MHz. This material has a miniaturization factor of a dielectric material with permittivity of 36, but with an impedance essentially matched to free space. Accurately measuring the permittivity, permeability, and loss values, however, presents challenges.
In the present work, we compare data from widely different test methods, including the Keysight Impedance Analyzer with 16453A and 16454A permittivity and permeability fixtures, coaxial airline perturbation, “full sheet resonance,” and phase length, insertion loss and impedance of microstrip transmission lines over a frequency range of 40 MHz to 4 GHz. We explain the causes of both random measurement error and systematic error in the various test methods.
BIO: Allen F. Horn, III Research Fellow, received a BSChE from Syracuse University in 1979, and a Ph. D. in chemical engineering from M.I.T. in 1984. Prior to joining the Rogers Corporation Lurie R&D Center in 1987, he worked for Dow Corning and ARCO Chemical. He is an inventor/co-inventor on 17 issued US patents in the area of ceramic or mineral powder-filled polymer composites for electronic applications.