Broadband Permittivity and Permeability Extraction of 3-D-Printed Magneto-Dielectric Substrates

Ilona Piekarz,Jakub Sorocki,Maurizio Bozzi

doi:10.1109/lmwc.2021.3100394

Abstract

A broadband microwave magneto-dielectric spectroscopy technique is introduced and dedicated to the characterization of 3-D-printed magneto-dielectric substrates. Complex permittivity and permeability are extracted for the material-under-test fabricated in the same manner and with the same orientation of the electro-magnetic (EM) field as in the intended applications that include, for example, miniaturized and efficient antennas. The information is derived from the measured characteristic impedance and propagation constant of a test microstrip transmission line. To exclude the influence of the coaxial-to-microstrip transitions, printed launchers are proposed with puzzle-like interlock to test substrate which is used together with a printed thru-reflect-line (TRL) de-embedding set. The presented technique was experimentally validated on an example of specialized magnetic polylactic acid (PLA) filament printed substrate in the frequency range 0.1–6 GHz and a reference PLA substrate measured with two different techniques to yield comparable results.

Highlights

T HE magneto-dielectric materials combining both dielectric and magnetic properties have been extensively studied in recent years for the realization of high-performance antennas [1], [2]
The methods described in the literature for magneto-dielectric materials are mostly narrow-band resonant techniques [3], [4], which may serve as a cross-verification rather than the main source of information in broadband applications
We introduce a low-cost and test fixture-free method dedicated to the broadband characterization of printable magneto-dielectric materials

Summary

INTRODUCTION

T HE magneto-dielectric materials combining both dielectric and magnetic properties have been extensively studied in recent years for the realization of high-performance antennas [1], [2]. The main drawbacks of this technique are the requirement for thickness, size, and shape of the sample along with the need for waveguide or coaxial measurement setup [6] Another broadband approach that uses a more applicationspecific setting is, for example, the microstrip line method that uses a test line fabricated on a substrate being the material of interest [7]. The main drawbacks of the method are the need for a sample with two-sided metallization to fabricate conductive strips and the use of a specialized test fixture, like in [8], to launch the wave from a coaxial line into a microstrip Such fixtures introduce a discontinuity/impedance step of which must be de-embedded from measurements and usually accept a narrow range of substrate thicknesses.

PERMITTIVITY AND PERMEABILITY DETERMINATION

Coaxial-to-Microstrip Launcher and TRL Kit

CONCLUSION