Other

Compass Technology Group, LLC

University of Dayton

John Weber Schultz

James Geoffrey Maloney

Kathleen Maloney

Rebecca Schultz

Richard P Chartoff

Jill S Ullett

Brian L Petrie

Crystal L Bethards

Various examples related to microwave dielectric analyzers and their use are provided. In one example, a microwave dielectric analyzer includes a measurement apparatus having a conductive electrode that can couple to a microwave analyzer and processing circuitry that can determine a dielectric characteristic of the dielectric specimen using a reflection coefficient measured by the microwave analyzer. The dielectric characteristic can be determined using a computational electromagnetic model of the measurement apparatus. The reflection coefficient can be measured by the microwave analyzer with the dielectric specimen in contact with the conductive electrode and/or sandwiched between conductive electrodes. The conductive electrodes can be axially aligned, and the second electrode may not be coupled to the microwave analyzer.

Microwave dielectric analyzer

Various examples are provided for flat lens antennas and their operation. In one example, among others, an antenna includes electrically thin (W<<λhigh), highly conducting, TEM mode antenna arms fed at a first end by a balun. The TEM mode antenna arms can be embedded in a spatially varied anisotropic dielectric material. A separation between the TEM mode antenna arms can increase from the first end to a second end where the TEM mode antenna arms transition to resistive card (Rcard) terminations when the TEM mode antenna arms are separated by a distance Hr, where a ratio of Hr to a height (H) of the antenna is in a range from about 0.2 to about 0.8.

Flat lens antenna

Various examples are provided for fragmented aperture antennas. In one example, a fragmented aperture antenna includes a two-dimensional lattice of conducting elements, where positioning of the conducting elements in adjacent rows are offset based upon a fixed skew angle. In another example, a fragmented aperture antenna includes a two-dimensional lattice comprising a combination of first and second geometric conducting elements, where a second geometric conducting element provides a connection between adjacent sides of diagonally adjacent first geometric conducting elements. In another example, a fragmented aperture antenna includes a two-dimensional lattice of conducting elements having a single common non-rectangular shape, where the conducting elements interleave in a digitated fashion. Diagonally adjacent conducting elements overlap along a portion of adjacent edges of the diagonally adjacent conducting elements.

Fragmented aperture antennas

Various examples of methods and systems are disclosed for correction of phase and amplitude errors that occur in transmission lines connecting transmitter/receiver devices to measurement fixtures. In one example, a method is described that includes using time domain processing to determine a phase shift from the measurement fixture that can occur between calibration measurements and measurements of the specimen under test. In another example, a method is described that includes frequency-domain processing of the signals to obtain both phase and amplitude corrections. Including these phase and amplitude corrections in the calibration procedure can reduce or minimize the errors induced in the measurements when the transmission line(s) experience either temperature changes or physical deflections, among other things.

Correction of transmission line induced phase and amplitude errors in reflectivity measurements

Various examples of methods and systems are disclosed for non-contact determination of coating thickness. In one example, among others, a method includes illuminating a surface having a layer of a coating material with electromagnetic (EM) energy transmitted at two or more frequencies, obtaining measured reflection data from reflected EM energy, and matching the measured reflection data to modeled reflection data of a reflection model based upon minimization of an error between the measured reflection data and the modeled reflection data to determine a measured thickness of the layer. In another example, a system includes a probe configured to illuminate an area of the surface including a layer of a coating material with EM energy and receive reflected EM energy, and a processing device configured to determine a measured thickness of the layer based upon minimization of an error between measured reflection data and modeled reflection data.

Non-contact determination of coating thickness

An electromagnetic chamber absorber provided improved absorption across a wideband and both lower diffuse and specular scatter and a method for constructing the same. An exemplary device can compromise a periodic arrangement of disconnected electromagnetically lossy elements where the periodicity of the lattice is adjusted to suppress all or most grating lobe scattering. Because the electromagnetically lossy elements are disconnected, scalable manufacturing approaches are enabled. The lossy elements can be easily fabricated via shaping, which includes rolling, folding and cutting resistive and/or magnetic sheet materials. The lossy elements can be repeatably placed in a periodic lattice using low density scaffolding approaches and/or other alignment mechanisms. The absorption at the lower frequency part of the electromagnetic bands (below 1-2 GHz) can be improved via the addition of parallel lossy sheets into the low-density scaffolding.

Low diffuse scatter, anechoic chamber absorber

Various examples of methods and systems are provided for traveling wave spot probes. In one embodiment, among others, a traveling wave spot probe includes one or more antennas positioned proximate to a coated surface. The one or more antennas can be configured to excite a surface traveling wave moving over an area under test by launching radio frequency (RF) energy at approximately a grazing angle to the coated surface under test. The one or more antennas can be positioned on a base placed proximate to the coated surface. The base can define the area of the coated surface under test. In another embodiment, a method for non-destructive testing of a coated surface includes positioning one or more antennas proximate to a coated surface and exciting a surface traveling wave over an area under test by transmitting RF energy via at least a portion of the one or more antennas.

Traveling wave spot probe

Method for making a low diffuse scatter, anechoic chamber absorber

A method and apparatus for producing ordered parts by from non-ordered liquid crystal monomers. Liquid crystal monomers contain stiff, rod-like mesogenic segments which can be aligned by an external force such as shear, electric field or magnetic field, causing an anisotropy in properties. When cured in the aligned stated by photopolymerizing the aligned monomers the anisotropic structure is &ldquo;locked in&rdquo; resulting in materials with anisotropic physical and mechanical properties. The rigid structure of the mesogenic segments can result in cured networks with high glass transition temperatures if the spacer groups which connect the mesogenic core with the reactive end groups are kept short. Glass transition temperatures of postcured parts ranged from 75 to 148&deg; C. depending on resin and processing conditions. A mechanical anisotropy on the order of two was measured for aligned samples.

Methods and apparatus for producing ordered parts from liquid crystal monomers

A method and apparatus for producing ordered parts by stereolithography from non-ordered liquid crystal monomers. Liquid crystal monomers contain stiff, rod-like mesogenic segments which can be aligned by an external force such as shear, electric field or magnetic field, causing an anisotropy in properties. When cured in the aligned stated by photopolymerizing the aligned monomers the anisotropic structure is 'locked in' resulting in materials with anisotropic physical and mechanical properties. The rigid structure of the mesogenic segments can result in cured networks with high glass transition temperatures if the spacer groups which connect the mesogenic core with the reactive end groups are kept short. Glass transition temperatures of postcured parts ranged from 75 to 148.degree. C. depending on resin and processing conditions. A mechanical anisotropy on the order of two was measured for aligned samples.

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Alpharetta, GA, United States of America

John Weber Schultz