Analysis of a novel non-contacting waveguide backshort

A new non-contacting waveguide backshort has been developed for millimeter and submillimeter wave frequencies. The design consists of a metal bar with rectangular or circular holes cut into it, which is covered with a dielectric (mylar) layer to form a snug fit with the walls of a waveguide. Hole geometries are adjusted to obtain a periodic variation of the guide impedance on the correct length scale, in order to produce efficient reflection of RF power. It is a mechanically rugged design which can be easily fabricated for frequencies from 1 to 1000 GHz and is thus a sound alternative to the miniaturization of conventional non-contacting shorts. To aid in high-frequency design, a rigorous full-wave analysis has been completed, which will allow variations of the size, number and spacing of the holes to be easily analyzed. This paper will review the backshort design and the method developed for theoretical characterization, followed by a comparison of the experimental and numerical results. Low frequency models operating from 4-6 GHz are shown to demonstrate return loss of greater than -0.2 dB over a 33 percent bandwidth. The theory is in good agreement with measured data

Electro-optic field mapping system utilizing external gallium arsenide probes

External electro-optic probes fabricated from two different crystal orientations of GaAs have been implemented in an electro-optic sampling system that is capable of mapping three independent orthogonal components of free-space electric fields. The results obtained for the radiated field from a microstrip patch antenna by the GaAs probes are compared with results on the same antenna obtained using bismuth silicate and lithium tantalate probes. An 8 μm spatial resolution has also been demonstrated for the electro-optic field-mapping system, and the capability for the system to measure field patterns at frequencies up to 100 GHz has been shown. © 2000 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70294/2/APPLAB-77-4-486-1.pd

A comparative study between shielded and open coplanar waveguide discontinuities

A comparative study between open and shielded coplanar waveguide (CPW) discontinuities is presented. The space domain integral equation method is used to characterize several discontinuities such as the open-end CPW and CPW series stubs. Two different geometries of CPW series stubs (straight and bent stubs) are compared with respect to resonant frequency and radiation loss. In addition, the encountered radiation loss due to different CPW shunt stubs is evaluated experimentally. The notion of forced radiation simulation is presented, and the results of such a simulation are compared to the actual radiation loss obtained rigorously. It is shown that such a simulation cannot give reliable results concerning radiation loss from printed circuits

A Systematic Review of Argumentation Related to the Engineering-Designed World

Background Across academic disciplines, researchers have found that argumentation‐based pedagogies increase learners\u27 achievement and engagement. Engineering educational researchers and teachers of engineering may benefit from knowledge regarding how argumentation related to engineering has been practiced and studied. Purpose/Hypothesis Drawing from terms and concepts used in national standards for K‐12 education and accreditation requirements for undergraduate engineering education, this study was designed to identify how arguments and argumentation related to the engineering‐designed world were operationalized in relevant literature. Methodology Specified search terms and inclusion criteria were used to identify 117 empirical studies related to engineering argumentation and educational research. A qualitative content analysis was used to identify trends across these studies. Findings Overall, engineering‐related argumentation was associated with a variety of positive learner outcomes. Across many studies, arguments were operationalized in practice as statements regarding whether an existing technology should be adopted in a given context, usually with a limited number of supports (e.g., costs and ethics) provided for each claim. Relatively few studies mentioned empirical practices, such as tests. Most studies did not name the race/ethnicity of participants nor report engineering‐specific outcomes. Conclusions Engineering educators in K‐12 and undergraduate settings can create learning environments in which learners use a range of epistemic practices, including empirical practices, to support a range of claims. Researchers can study engineering‐specific outcomes while specifying relevant demographics of their research participants

Self-Impedance of a Cavity Backed Slot Excited by a Stripline.

http://deepblue.lib.umich.edu/bitstream/2027.42/21037/2/rl0870.0001.001.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/21037/1/rl0870.0001.001.tx

Full-Wave Analysis of Microstrip Slot Antennas and Couplers.

http://deepblue.lib.umich.edu/bitstream/2027.42/21041/2/rl0877.0001.001.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/21041/1/rl0877.0001.001.tx