Dual Coaxial Probes in Transmission Inserted by Dielectric With Two Different Thicknesses to Extract the Material Complex Relative Permittivity: Discontinuity Impacts

Abstract

After a thorough investigation, this paper introduces a novel and simple radiofrequency material characterization technique. For this study's purposes, two probes were developed and separated by the sample under test (SUT) with an inhomogeneous test cell. Furthermore, the discontinuity impacts at the probe, SUT interfaces, were also studied. The investigation uses the transmission process through the principle of two different SUT thicknesses to measure its relative permittivity and loss tangent. The technique is based on using the lumped elements of an equivalent circuit of the entire test cell and covers 1 MHz-2 GHz. With the SUT, placed between two metal probes and another metallization, placed under its thickness on an opposite side to improve the loss tangent acquisition level, the cascading chain matrix (CCM) is used to get the final parameters. The thickness changing makes it possible to overcome the contact interface effects probe-sample. A mathematical model has also been presented through the fitting procedure. The new technique has been validated with three materials: Rogers RO4003C, FR-4 HTG-175, and Alumina 99.6%. The SUT complex relative permittivity extraction makes the new approach suitable for the telecommunication industry and many others. The method is also ideal for materials with thickness sizing up to 3 mm around.

Probe with a metallic bowl termination to determine the electric material parameters from variable thicknesses

“…The literature is rich enough in the deep details of the methods involved [1,2]. This domain is classified into two leading families: destructive or non-destructive [3,4], resonant or non-resonant [5], one or two accesses [6], broadband or narrowband [7][8][9], and distributed or lumped elements. However, these two large groups present six primary approaches or methods for accessing the test sample's intrinsic parameters.…”

“…The material intrinsic parameters are the central column mapping the material's ability to react under the excitation of an electromagnetic wave. Thereby, the probe (in transmission or reflection) [7,10,11], free-space (antenna or ellipsometry) [12][13][14], cavity [15][16][17][18], parallel plates capacitor (MIM) [19][20][21], inductive (spiral approach) [22,23], and transmission line (stub, short-circuit, waveguide, etc) [24][25][26]. All these methods are based on the perturbation [27][28][29] of the electromagnetic field lines in the insertion environment of the sample to be characterized.…”

“…As several publications work for [11][12][13], an open-coaxial-ended probe is used for wafer material instead of liquid. The novelty of the proposed approach is carried out by removing the effects of the interfaces because of the variation of the thickness [7,28], and the mathematical definition of the capacitor, allowing us to go back to the intrinsic parameters of the MUT. Scanning a frequency range from 1 MHz to 2.2 GHz with an Anritsu MS4642B 20 GHz vector network analyzer (VNA), the suggested approach has been experimentally validated with Alumina 99.5% and FR-4 HTG-175.…”

Tri-Band Bandpass Filter Using Mixed Short/Open Circuited Stubs and Q-Factor With Controllable Bandwidth for Was, Ism, and 5g Applications

“…The Q-factor is also used to mismatch the system at the chosen frequency f 0 and create a notched band. The microstrip technology [53] is used with a mono-layer of FR4 HTG-175 having thickness 1-mm where the dielectric constant ε r = 4.4 and loss tangent tan δ = 0.02 [54]. As reported in other works [55], we present results in terms of return loss (RL), insertion loss (IL), attenuation coefficient (AC), fractional bandwidth (FBW), center frequency (CF), and prototype's size surface (S).…”