Radio frequency field device

Fig, 6,15 Scheme of an NMR device. The field strength influences resolution and sensitivity of the measurement. Bq = permanent magnetic field. Transmitter and receiver for superimposed radio frequency field. Adapted with kind permission from [222]... 

Radio Frequency Field Another kind of device uses a radio frequency field. Electronic circuitry that creates the field detects the presence of a human body or body part. An antenna positioned around the point-of-operation creates the field. The antenna may be a wire or conduit. The sensitivity of the field is adjustable. Grounding characteristics for an operator may change with position and other factors, such as humidity and conductivity of shoes, and affect the rehabihty of some models. 

Initiation by Radio Frequency (RF) Radiation. RF radiation, ie, radio wave radar transmitters can, under certain circumstances, initiate electroexplosive devices. This topic will be discussed under Radio Frequency Radiation, Effects on Explosives. Also see articles on Electromagnetic Compatibility Electromagnetic Field Hazard, Simulated in Vol 5, pp E70-71 and Electric Blasting Caps and RF Energy in Vol 5, p E25-L... 

Microwaves are electromagnetic radiation placed between infrared radiation and radio frequencies, with wavelengths of 1 mm to 1 m, which corresponds to the frequencies of 300 GHz to 300 MHz, respectively. The extensive application of microwaves in the field of telecommunications means that only specially assigned frequencies are allowed to be allocated for industrial, scientific or medical applications (e.g., most of wavelength of the range between 1 and 25 cm is used for mobile phones, radar and radio-line transmissions). Currently, in order not to cause interference with telecommunication devices, household and industrial microwave ovens (applicators) are operated at either 12.2 cm (2.45 GHz) or 32.7 cm (915 MHz). However, some other frequencies are also available for heating [1]. Most common domestic microwave ovens utilize the frequency of 2.45 GHz, and this may be a reason that all commercially available microwave reactors for chemical use operate at the same frequency. 

In a quadrupole device, not as accurate and precise as double-focusing instruments but fast, a quadrupolar electrical field comprising radio-frequency (RF) and direct-current components is used to separate ions. Quadrupole instruments as mass analyzers are used together with ESI as the ion source the configuration employing a three-dimensional quadrupolar RF electric field (Wolfgang Paul, University of Bonn, 1989 Nobel prize for physics) is referred to as an ion trap analyzer (see below). 

In addition to the term MEMS, categories like microoptoelectromechanical systems (MOEMS), radio-frequency MEMS (RF-MEMS), and MEMS for medical or biomedical application (BioMEMS) have been established. The market for microfabricated devices is still in its infancy and is growing with rates comparable to the first years of microelectronics. According to one market research report, the sales of microfabricated systems was 12 billion in 2004 and is expected to grow with a CAGR of 16% to 25 billion in 2009 [6]. Recent extensions of fields of application are consumer, entertainment, and homeland security. Upcoming new devices are MEMS microphones, microenergy sources, micropumps, chip coolers, and micromachined wafer probes, and this will definitely not be the end of new developments. 

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