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William Cyrus Brown

    Father of Microwave Power Transmission(MPT)

    Bill Brown (1916-1999), was born on an Iowa farm. He earned his BSEE degree at Iowa State University. Initially working at RCA in Camden, NJ, he took a scholarship opportunity to go back to school, earning his MSEE at MIT in 1939. He joined the Raytheon Company and was soon in charge of the magnetron product line. He invented a cousin to the magnetron, the "amplitron", (or Cross Field Amplifier). Unlike the magnetron, which was just an oscillator, the amplitron could amplify a broad band of microwave frequencies. The amplitron had a long and successful career in military and space communications.  Later he designed and built the amplitron which powered the reliable and efficient long distance communications on the Apollo Moon missions, enabling the world to see and hear Neil Armstrong's immortal steps and words, "That's one small step for a man, one giant leap for mankind." directly from the Moon.  Brown modified his amplitron to greatly increase its power output, leading Brown to realize a new possibility - microwave power transmission (MPT), the key technology for Space Solar Power.

   Wireless power transmission had been suggested, but not successfully shown by Nikola Tesla and others, they incorrectly assumed that power density always fell off as the square of the distance. Through theoretical and experimental work by G. Goubau, Schwering and others it was learned that at high frequencies, such as microwave frequencies, power flow can become highly efficient and can be transmitted with efficiencies approaching 100 percent by a beam waveguide.

    Hardware necessary to enable microwave generation had become available through the work of many researchers, including Bill Brown, on radar and other work during WWII and subsequent years.  Armed with that research, Bill Brown then demonstrated MPT showing a small helicopter powered by a microwave beam stayed aloft at 60 feet for 10 hours; featured in 1964 on Walter Cronkite's newscast, showing publicly the value of this new capability. Bill invented the rectifying antenna, or rectenna, in 1964 and patented it in 1969.

                                      Brown and Peter Glaser @ Boston
                                      Science Museum
Bill Brown, far right and Peter Glaser far left explain their Solar Power Satellite to school children at Boston's Science Museum. The museum director is in the center.

Dr. Peter Glaser at Arthur D. Little invented and patented the first solar power satellite (SPS) design in 1968, now in the public domain. Bill and Peter immediately recognized the mutual dependency between Peter's new SPS and Bill's MPT work.

Dr. John Osepchuk edited a special issue of the Journal of Microwave Power in 1970 called "A Satellite Solar Power Station and Microwave Transmission to Earth," containing seminal papers by Goubau, W.J. Robinson, P. Guenard, V.J. Falcone, P. Glaser,  Bill Brown and others.

Brown set power transfer efficiency records that are still unbroken to this day: 92% RF-DC efficiency, DC-RF-DC efficiency of 54% at 1 KW, and later 34 kW transferred one mile with a collection efficiency of 82.5%

        Wireless Power Transfer 1974
The record-setting Microwave Power
Beaming Demonstration in 1975 - video

Bill Brown Tuning
                                a Rectenna
    The Space Solar Power Institute determined that SSP's lagging technology is microwave power beaming, moving the energy from GEO to the grid. Other key technologies such as space transportation are making progress more rapidly than MPT.
 Rectennas - "rectifying antennas" - which collect the radio frequency energy and thereby provide electric power have received growing support as Radio Frequency ID (RFID) technology, for example, one application of rectennas, have become more widely used.
Therefore, a major focus of the Space Solar Power Institute's efforts are in microwave power beaming, including rectennas.

This new concept to capture and gently and efficiently beam the sun's power directly into existing electric power grids on the Earth, has become an increasingly attractive idea to Japan, China, and many other countries desiring low-CO2 baseload power generation.

Bill was awarded the Microwave Pioneer Award in 1995, and IEEE-MTT's highest honor, the Microwave Career Award in 1999 for a "lifetime career of meritorious service and technical excellence".  Learn more about his work at the IEEE-MTT Career award reception address on youtube. - accepted in his behalf by his colleague and friend Dick Dickinson.


1. "Beamed Microwave Power Transmission and its Application to Space", IEEE Transactions on Microwave Theory and Techniques, Volume 40, No. 6, June 1992,
2. "The History of Power Transmission by Radio Waves", by William C. Brown, IEEE Transactions on Microwave Theory and Techniques, Volume MTT-32, No. 9, September 1984
3. The Microwave Pioneer Award in 1995,

4. The Microwave Career Award in 1999,
5. IEEE Global History Network,
6. US patent no. 3434678 Microwave to DC Converter William C. Brown, et al, filed May 5, 1965, was granted March 25, 1969.
7. "History of the Reentrant Beam CROSSED FIELD AMPLIFIER with emphasis on Noise Comparision with the Magnetron", by William C. Brown,

The family and friends of Bill Brown, with the Space Solar Power Institute, have endowed the William Cyrus Brown graduate Fellowship for MPT at the Georgia Institute of Technology to honor the father of microwave power transmission and continue his work by training the next generation of engineers to design and build a space solar power system. A donation button has been established for that purpose. We are also working to make his 3000 pages of personal journals publicly available.
Paul Jaffe(NRL) and James McSpadden(Raytheon)'s wrote an excellent overview of "Energy Conversion and Transmission Modules for Space Solar Power" for the June 2013 IEEE Proceedings which was entirely devoted to Wireless (Microwave) Power Transmission.