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In microwave-excited lighting systems, such as a sulfur lamp, a magnetron provides the microwave field that is passed through a waveguide to the lighting cavity containing the light-emitting substance (e.g., sulfur, metal halides, etc.). Although efficient, these lamps are much more complex than other methods of lighting and therefore not ...
The depth of penetration depends on the frequency of the microwaves and the tissue type. The Active Denial System ("pain ray") is a less-lethal directed energy weapon that employs a microwave beam at 95 GHz; a two-second burst of the 95 GHz focused beam heats the skin to a temperature of 130 °F (54 °C) at a depth of 1/64th of an inch (0.4 mm) and is claimed to cause skin pain without lasting ...
While Hull's magnetron was a HF device, Yagi was convinced that it could also be a generator of VHF or even UHF signals. Kinjiro Okabe was one of Yagi's first doctoral students and was encouraged by his mentor in this pursuit. In 1926, Okabe developed a magnetron device that significantly decreased the operating wavelength of oscillations. [1]
A microwave cavity or radio frequency cavity (RF cavity) is a special type of resonator, consisting of a closed (or largely closed) metal structure that confines electromagnetic fields in the microwave or RF region of the spectrum. The structure is either hollow or filled with dielectric material. The microwaves bounce back and forth between ...
Pyramidal horn antennas for a variety of frequencies. They have flanges at the top to attach to standard waveguides. A horn antenna is used to transmit radio waves from a waveguide (a metal pipe used to carry radio waves) out into space, or collect radio waves into a waveguide for reception.
Randall collaborated with Harry Boot, and they produced a valve that could spit out pulses of microwave radio energy on a wavelength of 10 cm. [3] On the significance of their invention, Professor of military history at the University of Victoria in British Columbia, David Zimmerman, states: "The magnetron remains the essential radio tube for ...
Initially Boot and Randall were awarded £50 each for the magnetron for "improving the safety of life at sea", but in 1949 Boot, Randall and Sayers received a £36,000 prize for their work. After a brief time at British Thomson-Houston , Rugby, in the latter years of the war, Boot returned to Birmingham as the Nuffield Research Fellow.
The antennas contained in mobile phones, including smartphones, emit radiofrequency (RF) radiation (non-ionizing "radio waves" such as microwaves); the parts of the head or body nearest to the antenna can absorb this energy and convert it to heat or to synchronised molecular vibrations (the term 'heat', properly applies only to disordered molecular motion).