Effective Permittivity Measurement of 3D-Printed Dielectric Crystals

Abstract

Additive manufacturing offers new possibilities in innovative antennas and microwave components. In order to fully exploit its potential, it is necessary to exploit the capabilities offered by the 3D printing technology fully. 3D-printed structured dielectrics are currently receiving much interest in this respect. However, the characterization of the dielectric properties of such crystal structures is not easy, and assumptions on such properties need to be made often. This paper shows a characterization of additively manufactured structured dielectrics in terms of their permittivity and loss tangent in a simple cubic (SC) and face-centered cubic (FCC) crystal geometry with different fill fractions. Measurement results are compared to values predicted by the Maxwell-Garnett effective media approximation and the effective refractive index extracted from a three-dimensional plane wave expansion method (PWEM) in the long-wavelength limit.

Broadband Effective Permittivity Simulation and Measurement Techniques for 3-D-Printed Dielectric Crystals

“…All the samples were manufactured with identical material and printing parameters 1 to ensure consistency of bulk material properties throughout the measurements. SC and FCC dielectric crystal samples are designed according to the method discussed in [16] with N = 3 spatial harmonics, with grating vectors equal to the individual reciprocal lattice vectors of the SC and FCC symmetries. Prior to measurements of dielectric crystal samples, printed bulk samples of the selected material were subjected to measurements with the resonative setup, and it was found that it obtained a relative permittivity of ε r = 2.66 and a loss tangent of tanδ = 0.0062.…”

“…In this work, we consider unit cells of different sizes, volumetric infills, and crystal symmetries created from a single material with relative permittivity ε r,i against the background of free space. The cells under investigation are generated via the method introduced in [15] and discussed in [16], which uses superimposed spatial harmonics along the reciprocal lattice vectors of the desired symmetry to create the geometry. The volumetric infill δ i of the cells is controlled via the inversely proportional related threshold parameter th.…”

“…Despite reports that the MG rule lacks accuracy at higher volume fractions [20], it has been used successfully to predict effective permittivities of DCs [16] and GRIN devices [21]. Fig.…”

“…The resonance measurement setup used in this work is based on a suspended microstrip ring resonator which has been introduced in [29] and used for the characterization of 3-D-printed dielectric crystals in [16]. Here, we use the resonant setup to test predictions about the effective permittivity obtained from the MGA theory, PWEM, and Floquet port simulations.…”

3D‐printed heterogeneous isotropic–anisotropic dielectric resonator for singly fed dual‐band circularly polarised antennas

“…3D‐printed homogeneous and anisotropic zirconia ceramics with large birefringence have also been demonstrated and applied to the design of a CP DRA [18]. Finally, heterogeneous isotropic DRAs combining materials with different dielectric constants have shown promising results for single‐band [19, 20], dual‐band [21], or wideband [22, 23] applications.…”