Robert A. Strangeway, Ph.D.
Professor
- Milwaukee WI UNITED STATES
- Allen Bradley Hall of Science S357
- Electrical Engineering and Computer Science
Dr. Robert A. Strangeway is an expert in electrical engineering, microwaves and electron paramagnetic resonance bridges.
Multimedia
Education, Licensure and Certification
Ph.D.
Electrical Engineering
Marquette University
1996
M.S.
Electrical Engineering
Marquette University
1986
B.S.
Electrical Engineering Technology
Milwaukee School of Engineering
1979
A.A.S.
Electronic Communications Engineering Technology
Milwaukee School of Engineering
1977
Biography
Dr. Robert A. Strangeway gained industrial experience as a millimeter-wave staff engineer with TRW in Redondo Beach, Calif. He has performed research and development in microwave and millimeter-wave engineering at the National Biomedical ESR Center, Medical College of Wisconsin, since 1983. He has co-authored several books on electric circuits, electromagnetics and transmission lines, and laboratory manuals.
Areas of Expertise
Accomplishments
Long Term Faculty Service Recognition, 35 years
Medical College of Wisconsin
2018
Education Partnership Award
Milwaukee Area Technical College
2008
Karl O. Werwath Engineering Research Award, MSOE
2007
Greek Advocate Award, MSOE
2005
Oscar Werwath Distinguished Teacher Award, MSOE
1992
Affiliations
- Institute of Electrical and Electronics Engineers (IEEE) : Member
- American Society for Engineering Education (ASEE) : Member
Event and Speaking Appearances
W-band EPR Bridge Equalization and Leakage
National Biomedical EPR Center Scientific Advisory Board Meeting Medical College of Wisconsin, Milwaukee, WI
2017-05-05
An Innovative Transfer Track from Associate in Applied Science in Electrical Engineering Technology to Bachelor of Science in Electrical Engineering
ASEE Annual Conference Indianapolis IN., June 2014
Multifrequency / Multiarm EPR Bridge Design Considerations
EPR Workshop 2010: Cutting-Edge Biomedical EPR Methods Workshop Milwaukee, WI, August 20, 2010
Multi-Arm Frequency Translation in EPR
EPR Instrumental Workshop Milwaukee, WI, May 6, 2005
A Versatile Q Band Electron Paramagnetic Resonance Spectrometer
Milwaukee, WI, August 26-27, 2004 Electro-Information (EIT) Conference
Research Grants
Vector Network Analyzer Project
Rockwell Collins Charitable Corporation University Allocations
Steven Holland and Robert A. Strangeway
2018
Selected Publications
An Effective Sequence of VNA Experiments for a Junior-Level Electromagnetics Course
IEEE Antennas and Propagation Society International SymposiumHolland, S.S., Brocker, D.E., Strangeway, R.A.
2023-12-07
There is a need for incorporating practical high frequency measurement experiences into an undergraduate electrical engineering (EE) program. This paper presents a sequence of experiments that develops student capabilities in vector network analyzer (VNA) measurements and component specifications formation. Students have demonstrated the effectiveness of this approach by constructing a datasheet for an unspecified RF/microwave filter as a summative experience.
Dispersion EPR: Considerations for Low-Frequency Experiments
Applied Magnetic ResonanceHyde, J.S,, Strangeway, R.A., Sidabras, J.W.
2021
Abstract: The hypothesis is made that the dispersion electron paramagnetic resonance (EPR) spectrum can yield a higher signal-to-noise ratio than the absorption spectrum in diagnostic examinations if phase noise in the bridge is under control. The rationale for this hypothesis is based on the observation that the dispersion spectrum becomes more intense than the absorption spectrum at high incident powers. The rationale is dependent on optimization of high microwave efficiency (Λ; mT/W1/2) and low quality factor (Q-value) resonators as well as the use of microwave sources with reduced phase noise. Microwave frequencies from 1.2 to 94 GHz are considered. Although the dispersion display appears to be observable with an adequate signal-to-noise ratio for most EPR research initiatives, a weakness of microwave bridges for studies at high incident microwave power was identified. Spurious leakage of incident microwave power through the circulator, thereby bypassing the probe leading to the resonator, can result in a decreased signal-to-noise ratio in both absorption and dispersion because of phase noise. For dispersion EPR with low Q-value sample resonators, this leakage is the primary contributor to phase noise at the receiver. In this work, we focus on the design of microwave reflection bridges and discuss possible methods to ameliorate this source of noise.
Broadband W-band Rapid Frequency Sweep Considerations for Fourier Transform EPR
Cell Biochemical BiophysicsStrangeway, R.A., Hyde, J.S., Camenisch, T.G., Sidabras, J.W., Mett, R.R., Anderson, J.R., Ratke, J.J., Subczynski, W.K.,
2017
A multi-arm W-band (94 GHz) electron paramagnetic resonance spectrometer that incorporates a loop-gap resonator with high bandwidth is described. A goal of the instrumental development is detection of free induction decay following rapid sweep of the microwave frequency across the spectrum of a nitroxide radical at physiological temperature, which is expected to lead to a capability for Fourier transform electron paramagnetic resonance. Progress toward this goal is a theme of the paper. Because of the low Q-value of the loop-gap resonator, it was found necessary to develop a new type of automatic frequency control, which is described in an appendix. Path-length equalization, which is accomplished at the intermediate frequency of 59 GHz, is analyzed. A directional coupler is favored for separation of incident and reflected power between the bridge and the loop-gap resonator. Microwave leakage of this coupler is analyzed. An oversize waveguide with hyperbolic-cosine tapers couples the bridge to the loop-gap resonator, which results in reduced microwave power and signal loss. Benchmark sensitivity data are provided. The most extensive application of the instrument to date has been the measurement of T1 values using pulse saturation recovery. An overview of that work is provided.
Hyperboliccosine waveguide tapers and oversize rectangular waveguide for reduced broadband insertion loss in W-band electron paramagnetic resonance spectroscopy. II Broadband Characterization
Review of Scientific InstrumentsSidabras, J.W., Strangeway, R.A., Mett, R.R., Anderson, J.R., Mainali, L., Hyde, J.S.
2016
Experimental results have been reported on an oversize rectangular waveguide assembly operating nominally at 94 GHz. It was formed using commercially available WR28 waveguide as well as a pair of specially designed tapers with a hyperbolic-cosine shape from WR28 to WR10 waveguide [R. R. Mett et al., Rev. Sci. Instrum. 82, 074704 (2011)]. The oversize section reduces broadband insertion loss for an Electron Paramagnetic Resonance (EPR) probe placed in a 3.36 T magnet. Hyperbolic-cosine tapers minimize reflection of the main mode and the excitation of unwanted propagating waveguide modes. Oversize waveguide is distinguished from corrugated waveguide, overmoded waveguide, or quasi-optic techniques by minimal coupling to higher-order modes. Only the TE10 mode of the parent WR10 waveguide is propagated. In the present work, a new oversize assembly with a gradual 90° twist was implemented. Microwave power measurements show that the twisted oversize waveguide assembly reduces the power loss in the observe and pump arms of a W-band bridge by an average of 2.35 dB and 2.41 dB, respectively, over a measured 1.25 GHz bandwidth relative to a straight length of WR10 waveguide. Network analyzer measurements confirm a decrease in insertion loss of 2.37 dB over a 4 GHz bandwidth and show minimal amplitude distortion of approximately 0.15 dB. Continuous wave EPR experiments confirm these results. The measured phase variations of the twisted oversize waveguide assembly, relative to an ideal distortionless transmission line, are reduced by a factor of two compared to a straight length of WR10 waveguide. Oversize waveguide with proper transitions is demonstrated as an effective way to increase incident power and the return signal for broadband EPR experiments. Detailed performance characteristics, including continuous wave experiment using 1 μM 2,2,6,6-tetramethylpiperidine-1-oxyl in aqueous solution, provided here serve as a benchmark for other broadband low-loss probes in millimeter-wave EPR bridges.
A Concise Antennas Course based on a Single Semester of Electromagnetics Preparation
ASEE Annual ConferenceStrangeway, R.A., Holland, Steven
2015
A Concise Antennas Course based on a Single Semester of Electromagnetics Preparation. A new undergraduate elective course that develops a background in antennas for senior electrical engineering students is presented. The course is only three quarter-credits long, that is, two semester-credits. An innovative aspect of this course is the modest prerequisite of only a Junior-level, four semester-credit lecture hours electromagnetics course or equivalent. In our quarter-based system, four semester-credit lecture hours translates into two courses of three quarter-credit lecture hours each. The prerequisite courses, required in our undergraduate electrical engineering curriculum, modulate the depth and breadth of topics, starting with vector algebraand coordinate systems and progressing through static fields, dynamic fields, transmission lines, plane waves, links, and electromagnetic interference principles. The integral forms of the fundamental electromagnetic relations are emphasized in these required courses. As a result, this antennas elective must incorporate pedagogically-selected background material such as differential operators and the differential forms of Maxwell’s equations, skin depth, and reflection and transmission of plane waves at material interfaces. The course builds a solid foundation in antenna principles that serves students continuing into advanced studies in graduate school as well as those entering industry after graduation.
Multiarm EPR Spectroscopy at Multiple Microwave Frequencies: Multiquantum (MQ) EPR, MQ—ELDOR, Saturation Recovery (SR) EPR, and SR—ELDOR
ChemiformHyde, J.S., Strangeway, R.A., Camenisch, T.G.
2012
W-band Frequency-swept EPR
Journal of Magnetic ResonanceHyde, J.S., Strangeway, R.A., Camenisch, T.G., Ratke, J.J., Froncisz, W.
2010
This paper describes a novel experiment on nitroxide radical spin labels using a multiarm EPR W-band bridge with a loop-gap resonator (LGR). We demonstrate EPR spectroscopy of spin labels by linear sweep of the microwave frequency across the spectrum. The high bandwidth of the LGR, about 1 GHz between 3 dB points of the microwave resonance, makes this new experiment possible. A frequency-tunable yttrium iron garnet (YIG) oscillator provides sweep rates as high as 1.8 × 105 GHz/s, which corresponds to 6.3 kT/s in magnetic field-sweep units over a 44 MHz range. Two experimental domains were identified. In the first, linear frequency sweep rates were relatively slow, and pure absorption and pure dispersion spectra were obtained. This appears to be a practical mode of operation at the present level of technological development. The main advantage is the elimination of sinusoidal magnetic field modulation. In the second mode, the frequency is swept rapidly across a portion of the spectrum, and then the frequency sweep is stopped for a readout period; FID signals from a swept line oscillate at a frequency that is the difference between the spectral position of the line in frequency units and the readout position. If there is more than one line, oscillations are superimposed. The sweep rates using the YIG oscillator were too slow, and the portion of the spectrum too narrow to achieve the full EPR equivalent of Fourier transform (FT) NMR. The paper discusses technical advances required to reach this goal. The hypothesis that trapezoidal frequency sweep is an enabling technology for FT EPR is supported by this study.
Saturation Recovery EPR and ELDOR at W-band for Spin Labels
Journal of Magnetic ResonanceFroncisz, W., Camenisch, T.G., Ratke, J.J., Anderson, J.R., Subczynski, W.K., Strangeway, R.A., Sidabras, J.W., Hyde, J.S.
2008
A reference arm W-band (94 GHz) microwave bridge with two sample-irradiation arms for saturation recovery (SR) EPR and ELDOR experiments is described. Frequencies in each arm are derived from 2 GHz synthesizers that have a common time-base and are translated to 94 GHz in steps of 33 and 59 GHz. Intended applications are to nitroxide radical spin labels and spin probes in the liquid phase. An enabling technology is the use of a W-band loop-gap resonator (LGR) [J.W. Sidabras, R.R. Mett, W. Froncisz, T.G. Camenisch, J.R. Anderson, J.S. Hyde, Multipurpose EPR loop-gap resonator and cylindrical TE011 cavity for aqueous samples at 94 GHz, Rev. Sci. Instrum. 78 (2007) 034701]. The high efficiency parameter (8.2 GW−1/2 with sample) permits the saturating pump pulse level to be just 5 mW or less. Applications of SR EPR and ELDOR to the hydrophilic spin labels 3-carbamoyl-2,2,5,5-tetra-methyl-3-pyrroline-1-yloxyl (CTPO) and 2,2,6,6,-tetramethyl-4-piperidone-1-oxyl (TEMPONE) are described in detail. In the SR ELDOR experiment, nitrogen nuclear relaxation as well as Heisenberg exchange transfer saturation from pumped to observed hyperfine transitions. SR ELDOR was found to be an essential method for measurements of saturation transfer rates for small molecules such as TEMPONE. Free induction decay (FID) signals for small nitroxides at W-band are also reported. Results are compared with multifrequency measurements of T1e previously reported for these molecules in the range of 2–35 GHz [J.S. Hyde, J.-J. Yin, W.K. Subczynski, T.G. Camenisch, J.J. Ratke, W. Froncisz, Spin label EPR T1 values using saturation recovery from 2 to 35 GHz. J. Phys. Chem. B 108 (2004) 9524–9529]. The values of T1e decrease at 94 GHz relative to values at 35 GHz.
Future of Engineering Technology - A Proposal
ASEE Annual Conference & ExpositionStrangeway, R.A., Holland, Steven, Kelnhofer, Richard, Petersen, Owe, Chandler, Edward
2010
The question of what is the future of engineering technology has been debated for many years. The discipline has seen a substantial decline in program enrollments over the years and the uncertainty of its place in the university academic setting continues. We believe a fundamental change of direction for engineering technology is needed, a change based on the needs of its core constituents – students/alumni and industry.
Our experience suggests that students and alumni of four-year engineering technology programs expect an engineering career. There are few occupational positions above the rank of technician that contain the word “technologist” in the job title. There is, however, strong demand for qualified graduates who can work as engineers to solve technical problems, communicate technical information, and work well in a team environment. Qualified four-year engineering technology graduates satisfy this skill set, that is, they possess the skills that are required for most positions offered to graduates of baccalaureate engineering programs.
