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Biography: Kiyo received a bachelor’s degree in electrical engineering from Caltech in 1940 and a master’s degree in communications engineering from Columbia in 1941. He earned a Ph.D. in engineering science and applied physics from Harvard in 1948. The following year Kiyo joined Sperry Gyroscope Co., a division of Sperry Corp., an electronics company, in Palo Alto, Calif. He left in 1955 to work for General Electric first at the company’s Palo Alto office and later at its offices in Philadelphia and Schenectady, N.Y. After corporate mergers, he was employed by Lockheed Martin and retired from there in 2005.
IEEE Activities: Kiyo was an active IEEE volunteer for nearly six decades. In 1955 Kiyo joined the Administrative Committee of the IEEE Professional Group on Microwave Theory and Techniques (now the IEEE Microwave Theory and Techniques Society). He was editor of IEEE Transactions on Microwave Theory and Techniques from 1958 to 1959 and served as president of the society from 1960 to 1961. In 1980 Kiyo joined the IEEE Geoscience and Remote Sensing Society and later served as the society’s first Awards chair. He was named an honorary life member of the administrative committees of both societies and continued to volunteer until shortly before his passing.
Jesse Taub - Retired: Airborne Instruments Laboratory, Long Island, NY
H George Oltman - Retired, Hughes Aircraft Company, Albuquerque, NM
Alvin Clavin - Retired: Hughes Aircraft Company, Carlsbad, CA
Jerry Hausner - Retired: Owner, Electro Science Technologies, Goodyear, AZ
H Clark Bell - HF Plus, Chatsworth, CA
Dr Richard V Snyder, President, RS Microwave, Butler, NJ
Dr Seymour B Cohn died at age 95. He outlived most co-workers and friends who knew him personally and who were personally aware of his many major contributions to our microwave technology. Hence, the six listed speakers are the only microwave engineers who we have been able to locate that had a personal relationship with Dr Cohn and, who can speak knowledgeably about the man and some of his major contributions to our microwave technology. Below is a synopsis of Dr Cohn's impact on microwave technology that the six speakers will address while adding their personal perspectives of the man.
Synopsis of Speakers Reflections
To say that the world and our industry has lost a titan with the passing of Dr Seymour B. Cohn would be an understatement. Seymour Cohn was a major contributor to microwave engineering from his first job at the Harvard Radio Research Lab (HRRL) during World War II and throughout his long and fruitful career. His exposure to microwave technology there, in those early years of the blossoming microwave industry, presented him with many issues that needed exploring. He responded with major contributions to the microwave technology of the period: stripline, isolators, waveguide-to-coax transitions, power dividers, ridged waveguide, directional couplers, and, most importantly, filter theory. His chapters in the book “Very High-Frequency Techniques” (1947) authored by engineers and scientists of HRRL was an important contribution to filter design and was Seymour’s start.
His research and writings provided part of many engineers on-the-job education and greatly enhanced their ability to design difficult components. At least two of his many papers can be considered to be classics for their impact on technology so significant in that era in the development of microwave technology.
l. Problems in Strip Transmission Line, which was published in the March 1955 MTT Transactions, derived formulas for the characteristic impedance and attenuation loss in shielded strip line. This early work helped engineers to design strip line circuits and was a big factor in making printed circuits a viable option at microwave frequencies. Microstrip transmission line technology soon followed.
2. “Direct-Coupled-Resonator Filters” which was published in the February 1957 IRE Proceedings. This paper put forth the concept of a low pass prototype filter and showed how it can be used to design lumped element and transmission line band pass filters using frequency transformations. It paved the way for subsequent advances by others that took advantage of the Richards transformation and Kuroda’s identity that generated other microwave filter structures.
His major contributions in the 1950’s and 1960’s were done well before the computer became a ubiquitous design tool. His outstanding ability to use his strong grounding in field and network theory to analyze, gain an understanding of a microwave component, and create practical results and inventions, makes him one of the few giants of microwave engineering. Furthermore, his papers were always written to be easy for the design engineer to use. Quite often an involved mathematical formula was reduced to a handy design graph. Before the computer era, the microwave engineering field was blessed to have the contributions of Seymour Cohn.
Dr Cohn’s developments were so significant that by 1959, just eleven years after receiving his PhD, he was elected a Fellow of the IRE (IEEE). (See citation below)
He earned is BEE degree at Yale in 1942 then joined HRRL developing military electronics for the war effort. He was appointed leader of a microwave filter and tuner project where he did considerable original research and development. His group mastered techniques of designing all types of low-, high-, and bandpass filters using coaxial line and waveguide elements. He wrote that “since most of my work at (H)RRL has been in new fields, I have been able to invent a great number of useful devices of fundamental importance”
In 1946 Seymour was awarded a pre-doctorate fellowship by the National Research Council for full time graduate study at Harvard. He was awarded his PhD in January, 1948. His thesis subject was on periodic structures contained within waveguide structures “for use as filters, and for slowing electromagnetic wave velocity in electron accelerators and traveling wave tubes”. After graduation, he worked at Sperry Gyroscope Co. until 1953 when he joined Stanford Research Institute. It was during this SRI period that he published the afore mentioned classic papers. Wanting a better balance of research and management, he left SRI in 1960 and joined the Rantec company as Vice President and Technical Director. At this point he had published 53 papers, many of which were major significance to our microwave industry, and he had been awarded 25 patents. Also it is at this point that these memorial speakers first developed their professional and personal relationships with Dr Cohn.
At Rantec Dr Cohn oversaw the engineering group (which included two of the speakers, Al Clavin and George Oltman), supported engineers with his knowledge and expertise, and responded to business opportunities, especially those that used his areas of expertise. One of these was the technology that led to Rantec’s commercial development of the world’s first Network Analyzer product, an instrument that measured both signal amplitude and phase (impedance) and plotted the result on a Smith chart or other graph of choice. Hewlett-Packard later became the dominant supplier of Network analyzers with their coaxial line versions.
In 1967 Dr Cohn decided to become a consultant. He incorporated as S. B. Cohn Associates and presented himself as a Microwave Component “Specialist” instead of “Engineer” to steer clear of potential legal issues that professional engineers occasionally faced. To limit his work load, he wanted only four core clients, two of which were Narda Microwave and Wavecom.
With Narda, he designed multi-octave directional couplers and got his taste of designing matching circuits for active components. Two very difficult tasks were to match a step recovery diode to a YIG filter over 4 octaves, and the output of an RCA power transistor over an octave. These accomplishments were key to the development of the microwave industry’s first ever, broadband, all solid state, microwave sweep generator. Jerry Hausner was the project engineer for this instrument. These achievements are truly remarkable and our community is fortunate that he documented and published that work so that all of us can benefit. He continued to consult for Narda Microwave until his retirement.
Dr. Cohn consulted with Wavecom for about 20 years supporting their filter and passive component line. Clark Bell, Wavecom’s primary interface with Dr Cohn, noted that he was well known for solving very complex problems by paying close attention to every detail. This observation is supported by the contents of his consulting notebooks, one or more for each client. These notebooks have been donated to the Historical Exhibit of the MTT Society and are displayed at it’s site in Maryland, and (in part) during each IMS at the Historical Exhibits.
Dr Seymour B Cohn died exactly 6 weeks short of his 95th birthday on September 9, 2015. He was married to his beloved wife, Florence (Hoffman), for 65 years until her death in December, 2013. He is survived by sons Bill (Lisa), Ric (Carol), and Peter; grandsons Rob and Miles, and his brother Leonard.
Dr Cohn’s IEEE Awards, MTT-S Awards, and MTT-S Offices:
MTT-S AdCom member since 1955.
IEEE Fellow - "For contributions to the theory and design of microwave components" 1959
MTT-S AdCom Chair(now renamed President) 1962-1963
MTT-S Microwave Prize in 1964
IEEE Lamme Medal in 1974
Honorary Life Member of the MTT-S 1978
MTT-S Microwave Career Award 1979
Honored as “Mr Microwave”, 1989 MTT-S IMS