David V. Rogers, Wolfhard J. Vogel
Robert K. (Bob) Crane passed in Newport, NH, on November 30, 2022, at the age of 86. Nature lover, outdoorsman, history buff, and radio propagation researcher extraordinaire, Bob contributed to the scientific community with a remarkable breadth of experimental and theoretical studies in ionospheric and tropospheric radio propagation, within a variety of professional venues. Among his affiliations were the Mitre Corporation, MIT Lincoln Laboratory, Environmental Research & Technology, Dartmouth College’s Thayer School of Engineering, and the University of Oklahoma (where he attained Professor Emeritus status in both electrical engineering and meteorology). Among many professional distinctions, he was an IEEE Life Fellow and a certified consulting meteorologist of the American Meteorological Society.
Editor’s Note
This article was originally published in the Radio Science Bulletin, Issue 378, and reprinted with permission.
Bob served for six years as international Chairman of URSI and was an officer of the URSI/US National Committee for fifteen years. He represented the United States numerous times in the Radiocommunication Sector of the International Telecommunication Union (ITU), and was responsible for writing many sections of then in-force ITU Radio Regulations. Bob worked in India under United Nations sponsorship with members of the Indian space program, in Australia on a month-long IEEE lecture tour, and also worked in Peru. Bob wrote two textbooks still used by college students and researchers today: “Electromagnetic Wave Propagation Through Rain” in 1996 and “Propagation Handbook for Wireless Communication System Design” in 2003.
Bob had a unique capability for adapting large existing measurement facilities to pioneering radio propagation research. He monitored low-orbit US Navy navigation satellites with the 46 m MIT Millstone Hill radar to estimate the variance and spectra of ionospheric angle-of-arrival and Doppler fluctuations. High-powered L-band and UHF radars at Kwajalein Atoll (Marshall Islands) were applied for high-resolution spatial and velocity observations of winds in the equatorial troposphere. He used other radar observations to analyze transhorizon propagation, rain-scatter interference, and the spatial structure of rainstorms. When adequate facilities did not exist, Bob built his own, such as his famous Rain-Range Experiment. The experimental studies were accompanied with thorough theoretical assessments and modeling to enable practical application of his research results, often in association with detailed subject-area reviews. His contributions to the understanding of propagation through rain are legend.
Because of the scope, high caliber, and longevity of Bob’s research, and his participation in such a broad range of venues, Bob influenced and inspired numerous other practitioners in the field. Reminiscences by a few of his many colleagues are shared here.
—David V. Rogers
Communications Research Centre Canada (retired)
—Wolfhard J. Vogel
University of Texas, Austin (retired)
Bertram Arbesser-Rastburg, IEEE Life Fellow; senior advisor, SpaceTec Partners; head, European Space Agency/European Space Research and Technology Centre Electromagnetics and Space Environment Division (retired); former chair, International Telecommunication Union Radiocommunication Sector (ITU-R) Study Group 3:
Back in 1984 I was working for INTELSAT in Washington, DC. Dave Rogers from COMSAT Labs called me one day and said: There is a meeting in Columbia, MD, to discuss propagation experiments with the NASA ACTS satellite – why don’t you join in?
This meeting brought together a good number of well-known people doing propagation research in the US at the time. I went there and was introduced to the chairman, Prof. Bob Crane, whose two-component rain model I had already used. I was pleasantly surprised to meet a soft-spoken but well-humored gentleman. His attitude was to encourage discussion and to get all participants to bring in their experience.
Later I attended numerous NAPEX meetings and always enjoyed his presentations and even more his contributions to the discussion. He had moved to the University of Oklahoma and kept working on improved slant-path propagation prediction models – at the same time investigating the requirements for equipment up-time to arrive at valid statistics for rainfall rate and beacon attenuation. I got involved in the work of the propagation Study Group of ITU-R and noticed that Bob Crane’s prediction models were considered most reliable and, combined with the rain climatic zones, most universally applicable.
The propagation community is indebted to Bob Crane for his great contributions to understanding the relationship between rain and atmospheric microwave attenuation.
I will always keep Bob in good memories.
Faramaz Davarian, Jet Propulsion Laboratory; former manager, NASA Propagation Program; project manager, Lunar Communication Terminal:
I became acquainted with Bob many years ago at a NASA Propagation Experimenters (NAPEX) meeting. This turned into a long-lasting friendship as I started managing the program. From the onset, it was clear that Bob was a world class expert in the field. Bob’s contributions to slant path propagation modeling and analysis were numerous, which received ample acknowledgment from his peers. The U.S. satellite industry organizations were heavy users of the NASA Propagation Handbooks during the 80’s and 90’s and beyond. Since Bob’s contributions to these handbooks and the related literature were substantial and high-quality, his name was well known among slant-path propagation enthusiasts.
On the personal note, I have many good memories with Bob, particularly on our ITU trips to Geneva. Bob was very knowledgeable on Switzerland, its geography and points of interest. He took me to most interesting parts of the country and the Swiss Alps; which, without him, I would not have been able to see on my own. I also enjoyed very much working with Bob; in addition to being a great expert in the field, he had good taste and good humor that he liked to share.
Louis J. Ippolito, IEEE Life Fellow; former principal investigator and manager, NASA Radiowave Propagation program; engineering consultant (retired), The George Washington University; United States National Committee of the International Union of Radio Science (USNC-URSI) Commission F; ITU-R Study Group 3:
I worked with Bob Crane since my earliest days at NASA and later through the years at various projects. He was a role model for me, one of the few engineers in the country at that time dedicated to radiowave propagation and its effect on communications. I went on to make that the focus for my career also. I remember when Bob was at Environmental Research & Technology and I was a young engineer at NASA Goddard, we funded a program with Bob for propagation research, and Bob developed something later called the Crane Global Model, which became the first propagation model, based on the use of geophysical data, to provide a self-contained rain attenuation prediction procedure for global application. The procedure later evolved into the Crane Two-component Rain Model, which further enhanced rain attenuation prediction. These models served as the basis for many other propagation models over the years and to this day, which further increased our knowledge of radio science and space communications. Bob’s legacy is solid, and those of us who had the pleasure of knowing and working with him are better for it.
David V. Rogers, Communications Research Centre Canada (retired); former member, Science Review Panel for NASA Propagation Program; former vice-chair, ITU-R Study Group 3:
My first interaction with Bob Crane was at the 1975 USNC/URSI meeting in Boulder, CO, as a Communications Research Centre Canada (CRC) postdoc. My paper with Rod Olsen, my CRC mentor into the radio propagation arena, estimated propagation delays in rain to assess any influence on (≈ 14 ns) guard-time objectives for TDMA satellite systems. We adopted delay/attenuation ratios to couple rain delay to (better-founded) rain attenuation, which also damped raindrop-size distribution effects, quite cleverly I thought. Bob was not that impressed, noting (correctly) that rain delay is small compared to clear-air delay. Still, dialogue with such an eminent figure was stimulating, and our analysis (with Dan Hodge, Ohio State) of the A = aRb attenuation-rainrate formalism, introduced at the 1976 Amherst, MA, meeting, had more cachet. Naturally, we leveraged Bob’s pioneering work on radio propagation through rain. As our paths continued to intersect, Bob and I became friends. Bob was in Geneva at my first ITU meeting in 1981 to educate me in those initially-perplexing proceedings. For NASA’s Advanced Communications Technology Satellite (ACTS) propagation program, Bob and I served as the Working Group chairs, motivating further collaboration and an extraordinary benefit as Bob’s coauthor on several papers. It was a privilege to work with such a master.
Wolfhard Vogel, IEEE Life Fellow; University of Texas at Austin (retired); former chair, USNC-URSI Commission F:
I met Bob Crane in the early 1970s, as I was starting out to measure the propagation effects of rain over terrestrial and satellite paths at centimeter wavelengths at the University of Texas at Austin. Attending appropriate sessions at URSI and IEEE conferences to learn what others were doing and also to present my own results, Bob often had calm words of encouragement and guidance about the requirements for statistically meaningful data. I always looked forward to having him participating in a session.
Later on, when NASA established the NAPEX (NASA Propagation Experimenters) Group managed through JPL, I got to know Bob on a more personal level. At one of our group meetings, he presented a report on his work and travel in India and it became clear that he very much included his family in his adventures, setting an example for all of us.
After visits to his homes in New Hampshire and Oklahoma, experiencing their organization and ambiance and chatting about his various collections, I realized that Bob had the uncanny ability to see the forest and not just the trees. His love for nature and its variability must have enabled him to create the important holistic propagation models that he is rightfully known for.
Digital Object Identifier 10.1109/MAP.2023.3328815