Contribution to the characterization of stratified structures : electromagnetic analysis of a coaxial cell and a microstrip line

The objective of this dissertation is the development of electromagnetic modelling software specific to the cells of microwave material characterization. This development is based on numerical methods that are alternative to finite element method which is widely used in commercial software. For the need to extract the properties of materials by inverse modelling methods, research into the numerical efficiency of direct analysis is the focus in this thesis. The characterization targeted cells in this work concern a coaxial cell and a planar line. The presence of an unknown material is modelled by a stratified heterogeneous transmission structure. The application of the transverse operator method (TOM) on the multi-layered coaxial cell allowed the determination of the propagation constant of fundamental mode and its corresponding field distribution of the electromagnetic fields, and the characteristics of higher-order modes for the need of the characterization of discontinuities between empty line and loaded line. In the case of the microstrip line, the use of the modified transverse resonance method (MTRM) allowed the determination of characteristics of the fundamental and higher order modes. Since each cell consists of several different sections, the matrix S of the set will be determined by the use of the several modal methods, such as modal connection method (''mode matching'') and multimodal variational method (MVM). The direct analysis codes are coupled with several optimization programs to constitute the software for extracting the material parameters. These are applied to material samples in cylinder form holed by the coaxial cell, or thin rectangular wafer by the microstrip line. Broadband extraction results were obtained, values are comparable with those published. Both high-loss dielectrics and nanostructured materials have been studied by our method

Frequency and Field Strength Materials Characterization with Complementary Split-ring Resonators, Coplanar Waveguides, and the Virtual Ground Method

Title from PDF of title page viewed May 20, 2020Thesis advisor: Anthony CarusoVitaIncludes bibliographical references (pages 69-71)Thesis (M.S.)--Department of Physics and Astronomy. University of Missouri--Kansas City, 2019In the radiofrequency bands, measuring the power-dependent complex permittivity and permeability of materials that undergo metal–insulator transitions is a significant challenge which is important for defense and commercial applications. This thesis attempts to articulate barriers in the prior art, and how the techniques described herein overcome such deficiencies. Specifically, using a combination of direct and indirect narrow-band resonant and wide-band, non-resonant heterostructures, with narrow gaps, application relevant electric fields were achieved, and complementary assessments of the measured S-parameters were determined. The heterostructures/fixtures include complementary split-ring resonator and coplanar waveguide instantiations. Additionally and complementary to the RF measurement systems, a ferroelectric test measurement system for high-frequency and high-power polarization vs. electric field curves was designed, built, tested, and shown to match baseline comparisons. The ferroelectric test system is a Sawyer–Tower variant using the virtual ground topology.Introduction -- Background -- Overview of measurement Techniques -- Coplanar waveguides and complementary split-ring resinators -- Virtual ground method -- Summary and future wor

Reduction of EMI due to common mode current using common mode filter or lossy material

This thesis consists of four papers. In the first paper, two new common mode filter structures were designed, fabricated, and measured. A sandwich-type EBG structure that resonates at the desired filter frequency is designed to suppress common mode filter on differential signals. The new filters are placed on top of the PCB as a surface-mount component, instead of being implemented within the PCB stackup. The total radiated power (TRP) of the implemented filter is investigated and discussed. RF absorbing material and traditional shielding are considered to reduce the TRP. In the second paper and third paper, new PCB-embedded common mode filters are designed and investigated. Based on a quarter-wavelength resonator, an inter-digital structure is designed having an electrical size of only 0.15 λ x 0.065 λ, where λ is the effective wavelength in the CM filter. Its interdigital structure is also capable of suppressing higher order harmonics of the CM signal and can be used for USB 3.0 to mitigate electromagnetic interference. Further, a novel broadband suppression structure is described that uses magnetically lossy material to suppress the CM signal from 4.6 to 20 GHz without strongly affecting the intended differential signal. In the fourth paper, a methodology for validating the parameters of magnetic absorbing materials was developed. The microstrip line test can be recommended as an easy-to-implement validation method for the measured material parameters. The heat sink model and simulation comparison has also been investigated to determine the radiation mitigation with lossy materials --Abstract, page iv

Impedance Transformers

Non

Compact COMM-NAV Antenna for Handset Application

In order to to reduce the amount of equipment a soldier must carry, a combined Communications and Navigation Antenna (COMM-NAV) antenna was proposed as a design objective at the MITRE Cooperation. This study aims to combine a UHF (communications)GPS (navigation) antenna into a single unit. The UHF band of interest was established to be 225MHz to 400MHz, whereas the GPS antenna is required to operate at L1 (1227MHz) and L2 (1575MHz) frequencies. This design is required to minimize interference between the two antennas. Through simulations and measurements, two antennas were designed to meet these requirements. The UHF antenna uses a sleeve monopole design, whereas a stacked, shorted annular ring design was selected to meet the GPS requirements

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

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

Study of FeTaN Films and FeTaN Lamination stack using microwave techniques.

Master'sMASTER OF SCIENC

A Miniaturized Phased Array Antenna Based on Novel Switch Line Phase Shifter Module

A miniaturized phased array antenna with a uniquely designed switch line phase shifter to obtain a steerable beam pattern is presented. A 1x4 phased array patch antenna is designed at 5 GHz using Rogers dielectric material with a relative permittivity of 6.15 and a thickness of 1.524 mm. Each element of the probe fed PAA are connected to a phase shifter on a different dielectric substrate. The phase shifter has four equal length microstrip lines placed in a circular fashion around a via that connects to the antenna at the center. The addition of each microstrip line is designed to provide a phase shift of 90⁰. This design provides the ability to place the phase shifter and feed to the antenna in space constrained locations. The maximum steering angle obtained was ±45⁰. This design is appropriate for Wi-Fi applications that requires directional beam pattern, Multiple Input Multiple Output (MIMO) communications, scanning radars, and other applications requiring steerable beam pattern. This design is patent pending