Invited Talk on Case Study in the Generation of High Power RF/Microwave Energy by Prof Peter Grant (Life Fellow, IEEE)
An IEEE UKRI APS/MTTS and YP AG Invited Talk on Case Study in the Generation of High Power RF/Microwave Energy by Prof Peter Grant (Life Fellow, IEEE).
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- Classroom 12, Alrick Building,
- King’s Building Campus, University of Edinburgh
- Edinburgh, Scotland
- United Kingdom
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Peter of University of Edinburgh
Case Study in the Generation of High Power RF/Microwave Energy
The magnetron is a device for producing radio frequency (RF) and microwave energy at frequencies between 1 GHz and 300 GHz. Early magnetron designs were investigated and patented by many groups in the late 1930s. Pre-1939, these designs used glass envelopes to enclose the vacuum and delivered generally only modest ~10 W power levels, well below the kilowatt values required for various applications.
The radical improvement in power was achieved by Birmingham University researchers through a novel anode design, in which the cavity resonator was drilled from a solid block of copper to achieve more efficient cooling and permit much higher output power. In February 1940, their first laboratory device produced 400 W at a wavelength of 10 cm, or 3 GHz.
In April 1940, Government sponsors contracted GEC, Wembley, to develop this into a manufacturable device requiring neither a vacuum pump nor an electromagnet. Conveniently, Maurice Ponte had brought to GEC French magnetron device samples incorporating an oxide-coated cylindrical cathode, which achieved a much longer operational lifetime. Eric Megaw's GEC-redesigned magnetron, fitted with a 6 lb permanent magnet and a thoriated-tungsten spiral cathode, then delivered an initial output of 3 kW on 29 June 1940.
As Britain lacked the manufacturing capability for the cavity magnetron in 1940, Winston Churchill agreed that Sir Henry Tizard should offer the design to the Americans, enabling the parallel development of magnetron-based radar systems in both Britain and America. The Americans quickly established the Radiation Laboratory at MIT, near Boston, which became the second largest wartime research facility after the Manhattan Project. High-resolution microwave airborne radar, which provided accurate ground mapping and facilitated the detection of surfaced U-boats, relied on the production of 250,000 cavity magnetrons.
Although cavity magnetrons are no longer used in radar today, they are found in microwave ovens across a global market exceeding $12 billion per annum, with 93% of UK households owning a microwave oven. This demonstrates clearly the enduring impact of Birmingham's academic innovations and GEC's subsequent industrial engineering advances, which continue to find application in industrial heating and drying systems today.
Biography:
Peter M. Grant is a Life Fellow of the IEEE. He received his BSc from Heriot-Watt University in 1966 and his PhD from the University of Edinburgh in 1975, honorary DEng degrees from Heriot-Watt University in 2006 and Edinburgh Napier University in 2007, and a further Honorary Doctorate from the University of Edinburgh in 2016.
He was appointed to the University of Edinburgh in 1971, later serving as the first Head of the School of Engineering from 2002 to 2008. His research was recognised with the 82nd Faraday Medal awarded by the IEE. In 1998–1999, he was appointed by the IEEE Signal Processing Society as a Distinguished Lecturer on DSP for Mobile Communications.
In 2007, he was appointed the 8th Regius Professor of Engineering at Edinburgh. In 2009, he was appointed an Officer of the Order of the British Empire (OBE) in the Queen's Birthday Honours List. He holds fellowships of EURASIP, the Royal Academy of Engineering, and the Royal Society of Edinburgh. He has served for 14 years as a Trustee of the James Clerk Maxwell Foundation, hosting museum visitors and delivering public historical talks on the life of Maxwell.