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Bill Brown’s Distinguished Career
by Richard M. Dickinson (SM ’83, LSM ‘98)
William C. Brown received the B.S.E.E. from Iowa State University in 1937 and the M.S.E.E. from M.I.T in 1941. He is a Life Fellow of the IEEE.
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He joined the Raytheon Co. in 1940, and became involved in making improvements in the design of magnetrons that were used in all World War II microwave radars. However, magnetrons are oscillators and were not suitable for the next generation of radars that needed an efficient, high powered and broadband amplifier. In 1952 he made a major contribution in fulfilling that need by converting the magnetron oscillator into a broadband amplifier. This device, variously referred to as the Platinotron, Amplitron or simply as the crossed-field amplifier (CFA) found immediate military and civil usage. These applications included the Navy Aegis radar, the Hawk and Patriot Missile Systems, commercial air route surveillance radar, and the high rate communications system in the Apollo lander that sent televised images from the Moon to Earth. For this contribution Mr. Brown received the MTT-S Pioneer Award in 1995.
Mr. Brown then proposed that the CFA be developed into a super power amplifier and the resulting DOD contract produced a CFA that generated 425 kW of continuous power with an efficiency of 76% at the frequency of 3 GHz. This represented a power increase by two orders of magnitude.
He then proposed the use of microwaves for WPT or Wireless Power
Transmission, and wrote the
first published article that explored the possibilities in 1961. Then, under
an Air Force contract he demonstrated in 1964, on the CBS Walter Cronkite
News, a microwave powered helicopter that received all the power needed for
flight from a microwave beam. Key to this flight was the "rectenna" which
was invented to absorb the microwave beam and simultaneously convert it to
DC power.
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Key to future applications of WPT is the overall efficiency or ratio of DC power output to DC power input. In the 1969 to 1975 time period, Mr. Brown managed a program that increased the overall efficiency, or ratio of DC power out to DC power in, to a JPL certified efficiency of 54%, several times greater than generally expected. He was also technical director of a JPL Raytheon program that beamed power over a distance of one mile to a rectenna which intercepted a portion of the beam and converted it to 30 kilowatts of DC power with 84% efficiency.
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Mr. Brown formally retired from Raytheon in 1984 but continued there as a consultant. Four volumes of his papers have been preserved in the MTT-S Museum in Baltimore. These same papers, over 2000 pages of final reports authored by Brown, four IBM-sponsored videotaped lectures at Northeastern University, and numerous historical physical artifacts have been transferred to archives at Texas A&M University. Microwave magnetrons and CFAs are on exhibit in the Raytheon Museum.
Bill Brown’s distinguished career created the microwave wireless power transmitting field as we know it today [1]. I believe that in the future through his efforts we will be able to use WPT to reach the stars, by using WPT technology to power photon pushed light sails for interstellar flight from our planetary system.
Bill’s career developments in high power microwave generation[2] and efficient rectification [3] were what prompted Peter Glaser[4] to propose the Space Solar Power Satellite System or SPS[5], that NASA and DOE studied extensively in the 70s and 80s. This may have prompted Bob Forward[6] to propose a photon pushed lightsail mission to Alpha Centauri in 1984, and a microwave powered version pushed by SPS beamed power in 1985 [7].
Bill’s career cut across many microwave activities involving work on cooker tube magnetrons, crossed field devices [8], rectennas and electronically steered phased array modules (ESPAMs). Bill impressed me very much with his ability to do multidisciplinary engineering. He learned to model and analyze control systems for helicopters, to calculate lift and drag forces on helicopters, airplanes and airships, to calculate the thermal heat balances for space objects, etc.
His grasp of Microwave Theory and Techniques was wide-ranging. In addition to designing the antenna, the RF transmission line impedance transformers and the microwave filter circuit design for the rectenna, Bill devised a VSWR probe assembly in front of a rectenna array in order to adjust the DC loads for low reflection impedance matching. He designed and fabricated an expanded waveguide test fixture for measuring the record reception-conversion efficiency of a single rectenna (92.5% at 6W RF input). In a related effort, he devised a split-ground plane assembly for carefully measuring all of the incident and reflected RF , DC output, and dissipated thermal energy in the rectenna diode and skin effect losses to accurately account for all elements of power loss.
Bill designed high power rectennas, very low power density rectennas, light weight rectennas, wafer thin rectennas for integrating into aircraft underwings, low-cost rectennas, and microwave and millimeter wave rectennas. He documented and reported on his work in chapters in Academic Press Electrical Science Series Microwave Power Engineering Books, NASA, Raytheon, and RADC reports. He wrote articles in The Journal of Microwave Power, IEEE Transactions, IMPI Journals, Conference Proceedings and Reports, AIAA Space Solar Power Review, and appeared in video taped lectures. He demonstrated microwave power generation, transmission and rectification to individuals such as Werner von Braun, Raytheon & NASA managers, and at diverse venues including MTT-S meetings, science museum audiences, college classes, and private gatherings. As of 1995 he had published over 70 papers and 50 patents in wireless power transmission and microwave tube technology.
Bill was a phenomenal builder equipped with very good analytic skills. In addition to his beautiful Fisher Body Napoleanic coaches, he built helicopter models, dual-mode Potter horns, strip ellipsoidal reflectors, motor-driven Earth globes with GEO SPS supported on beams for science fairs & museums, phase injection -locked magnetrons outfitted with buck-boost coils and variable output tuners for ESPAMs.
It was Bill Brown’s vision that the technology of free-space power transmission by microwave or laser beam will inevitably lead to an extension of our two dimensional electric grid system to three dimensions in which electrical power is routinely transmitted to and from space. Bill’s career is a model for now and future MTT Members to aspire to. More power to us.
Acknowledgement:
Some of the above material was graciously provided to me by one of Bill Brown’s four Daughters, Donna Salisbury via fax on Feb 11, 1999. I want to also acknowledge help from Dr. John Osepchuk of Full Spectrum Consulting, Peter Staecker, and Austin Truitt of MTT for providing some of the information on the career of Bill Brown.
William C. Brown - Honors and Service:
1945: Naval Ordnance Development Award
1950-1960: Member and later Deputy Director, Advisory Group on Electron Devices (AGED)
1947: Presidential Certificate of Commendation
1957: Fellow, IRE, "For contributions in the field of microwave tubes"
1964: IR-100 Award for super power amplitron (425 kW)
1966: Founding member of International Microwave Power Institute
1968: DoD Meritorious Civilian Service Award
1970: AES Barry Carleton Award (paper on use of microwave beam to power and position a helicopter)
1972: Professional Achievement Citation: Iowa State University
1978: Fellow, International Microwave Power Institute
1982: IR-100 Award for ultra-light printed circuit rectenna
1995: MTT-S Pioneer Award for converting the microwave magnetron into a broadband amplifier
References:
1. Brown, W., "The History of Power Transmission by Radio Waves," IEEE Trans. Microwave Theory Tech., Special Centennial Historical Issue, Vol. MTT-32, No. 9, pp. 1230-1242, Sept. 1984.
2. Brown, W., "The Amplitron: A Super Power Microwave Generator," Electron. Progress, Vol. 5, No. 1, pp. 1-5, July/Aug. 1960.
3. Brown, W., "Rectenna Technology Program: Ultralight 2.45 Ghz rectenna and 20 GHz rectenna," NASA Contractor Report CR 179558, Contract NAS3-22764, NASA LeRC, Mar. 1987.
4. Glaser, P., "Power From The Sun; Its Future," Science, Vol. 162, pp. 857-861, Nov. 22, 1968.
5. U.S. Dept. of Energy & NASA, "Satellite Power System, Concept Development and Evaluation Program," Reference System Report, DOE/ER-0023, Oct. 1978, Published Jan. 1979.
6. Forward, R., "Roundtrip Interstellar Travel Using Laser-Pushed Lightsails," Journal of Spacecraft and Rockets, Vol. 21, pp. 187-195, March-April, 1984.
7. Forward, R., "Starwisp: An Ultralight Interstellar Probe," Journal of Spacecraft and Rockets, Vol. 22, No. 3, pp. 345-350, 1985.
8.Brown, W., " The History of the Crossed-field Amplifier," IEEE MTT-S Newsletter, pp. 29-40, Fall 1995.