rf & microwave radiation safety handbook

[...]... wavelength of 1.03 × 10–7 metres (103 nm) which can be seen from Figure 1.8 lies just above the ultraviolet (UVc) spectrum The 14 RF and Microwave Radiation Safety Handbook Figure 1.8 Radiation wavelengths relative to 300 GHz (WHO) highest RF frequency used in standards for RF safety is 300 GHz which corresponds to a wavelength of 10–3 metres and lies in the EHF band of the radio frequency spectrum If... amplitude modulation depth versus transmitted RF power and RF current Figure 1.7 shows a pulse transmission where the carrier is transmitted for time tp (the pulse duration) and with a pulse repetition rate of n Hz (pulses per second) It is of course, not possible to show this to scale since there will 12 RF and Microwave Radiation Safety Handbook Figure 1.5 RF signal, amplitude modulated by a low frequency... non-ionising radiations Confusion between these two forms of radiation amongst the public has been mentioned earlier There is also a surprising amount of misunderstanding amongst electronics and radio engineers about the distinction between these two forms of radiation even amongst newly qualified graduate engineers, so that RF radiation is sometimes considered to be the same as ionising radiation Ionising radiation, ... roughly from 10 kHz to 300 GHz Table 1.3 illustrates the names for the various sub-divisions of the radio spectrum The term microwave , mentioned earlier, does not appear in the listing although with the advent of microwave ovens it has become 10 RF and Microwave Radiation Safety Handbook Table 1.2 Nominal quarter wave antenna length for a number of frequencies Frequency (MHz) Length – one quarter wavelength... 19 RF machines and RF plant RF energy is now increasingly used to undertake manufacturing operations which use heating and these terms are used here to refer to machines generally In practice they have functional names, e.g plastic bag sealer, plastic welder, etc Their significance is that they use an RF generator which, in terms of safety, needs the same consideration as any other RF generator 18 RF. .. RF generator which, in terms of safety, needs the same consideration as any other RF generator 18 RF and Microwave Radiation Safety Handbook Use of the decibel Whilst most people trained in electrical and electronic engineering will have covered this topic, experience in running RF radiation safety courses shows that whilst many people work regularly with decibels, a surprising number never have occasion... voltages, ionising radiation in the form of X-rays are produced and for this reason the subject is covered in some detail in Chapter 8 It should be clear that this ionising radiation is not inherent in the RF energy but rather that both forms of radiation can co-exist inside equipment and the RF engineer or technician needs to be aware of the hazards involved It is also the case that ionising radiation is,... of RF energy in a substance, normally human tissue, expressed in watt per unit mass, e.g watt per kilogram If the substance is not human tissue, it should be specified Note that a SAR limit may be expressed in this standard form but be limited to a maximum mass of tissue e.g 10 Wkg–1 (10 g) should be interpreted as an SAR of 10 Wkg–1 in any 10 gram of tissue 16 RF and Microwave Radiation Safety Handbook. .. showed transmitter sales to this area in terms of system power and 21 22 RF and Microwave Radiation Safety Handbook listed nine long wave (LF) and medium wave (MF) stations with powers exceeding 1 MW, most of them being rated at 2 MW In the HF broadcast field one station was shown as having 16 × 500 kW transmitters The potential safety hazards associated with the feeders and antenna systems can be imagined... sites make the job of ensuring the safety of riggers and maintenance personnel difficult and need to involve operation to a strict code of working practice It is difficult to show a meaningful picture of a large HF antenna site since the antenna wires can hardly be seen Figure 2.5 illustrates some HF wire antenna types as line drawings 24 RF and Microwave Radiation Safety Handbook Figure 2.3 GmbH) Telefunken .