SAFETY IN HIGH FREQUENCY ELECTROMAGNETIC FIELDS NARDA BROADBAND FIELD METER NBM-500 SERIES

2 Protecting humans and the environment from harmful effects is less concerned with things that occur naturally, but much more with problems that we have caused ourselves, such as noise, dangerous materials, electromagnetic radiation and radioactivity. Producers, equipment operators, employers, safety representatives, workplace safety bodies, and authorities are faced with great responsibility. The obligation to provide protection ranges from the workplace through to the public domain and even into the private sphere – in other words, the whole environment. Subjective senses can provide protection:...

3 • Guidelines for Limiting Exposure to Time-Varying Electric, Magnetic and Electromagnetic Fields (up to 300 GHz). International Commission on Non-Ionizing Radiation Protection (ICNIRP). Published in Health Physics, Vol. 74, No. 4, pp. 436-522, April 1998 • Guidelines on Limiting Exposure to Non-Ionizing Radiation. International Commission on Non-Ionizing Radiation Protection (ICNIRP), July 1999; ISBN 3-9804789-6-3 • Directive 2004/40/EC of the European Parliament and of the Council of 29 April 2004 on the minimum health and safety requirements regarding the exposure of workers to the risks...

5 In touch everywhere. Access from anywhere. For most people, this dream has become reality. Devices are getting more and more versatile. You can do much more than just make a phone call with the latest mobile phones. You can have wireless access to all Internet services with your notebook PC or your PDA. And, you can make that phone call if you want to. Radio networks have developed to keep pace: Wireless LANs and other wireless communications systems for local “islands”, mobile systems such as GSM, UMTS and CDMA for complete on-site coverage, coupled with wide area communications using fixed...

6 Radio and TV cover every area. Listeners and viewers expect high quality reception, even if they are a long way from the transmitter. Not everyone is connected by cable, and even the cable network needs a head end station that receives all programs perfectly. Apart from the modulation method used, high quality and long range are achieved through high output power levels. The same is true of non-public radio services: Police, rescue services, operational radio, and air traffic control. But even where no programming is being broadcast, there are other signals being used – such as radar to locate...

8 We can utilize high frequency electromagnetic radiation in a variety of ways. It can weld plastics, harden metallic surfaces, dry paints and enamels or wood and leather, or heat materials for industrial processes – as well as warming up our dinner in the microwave oven. The so-called ISM frequencies are reserved for these purposes (ISM = Industry, Science, Medicine). Example frequencies are 13.56 MHz, 27.12 MHz and 2.45 GHz – the frequency used by the microwave oven. WELD, HARDEN, HEAT, DRY By kind permission of Willems Industriële Producties B.V., www.willems-ip.nl

9 High frequency radiation is useful in science and medicine for non-invasive examination of materials or of the human body. As an example, modern nuclear magnetic resonance tomography makes use of superimposed high frequency fields. Diathermy and hyperthermy, i.e. deep tissue warming using electromagnetic fields, can promote or accelerate the healing process. Controlling the electromagnetic field strength is part of occupational safety. The industrial process should work on the material, and not make the operator sweat. In the same way, subjecting patients to controlled doses of radiation in...

10 You will often find that electromagnetic field strengths have to be measured in places that are awkward to get at. We have designed the Narda NBM-500 series of Broadband Field Meters so they can be used anywhere. The casings are impact-resistant, the probes are robust. The monochrome displays – backlit LCDs – can be read in the dark and in bright sunlight. So you still get reliable results, immediately, even under difficult working conditions. The tasks are many and varied, so right now Narda has two types of instrument on offer: NBM-520: FOUR BUTTONS FOR RESULTS This handy device tells you...

11 NBM-550: THE EASY WAY TO FINE DETAIL This instrument provides additional convenient on-site evaluation features as well as memory space for up to 5000 results, so you can analyze them and document them later. You can use it as a hand-held device, or position it precisely using a tripod. You can program it for long-term measurements, or remote control it from a PC. A STRONG FAMILY All the instruments in the NBM-500 series really do belong to a family. The probes are designed to work with both instruments and are therefore completely interchangeable. Also, you can control the “small” NBM-520...

There’s an NBM probe for virtually every application. E-field probes with exceptionally broad bandwidths detect electric field strengths at frequencies ranging from long waves up to microwaves. H-field probes make separate measurements of the individual magnetic field components in the vicinity of transmitters or industrial equipment, where high currents are flowing. So-called shaped probes automatically evaluate the field strength in compliance with a specific human safety standard. ISOTROPY All NBM probes are isotropic, i.e. non-directional. You don’t have to think about what direction the...

13 EXAMPLE: E-FIELD PROBE TYPE EF0391 This probe has a frequency range from 100 kHz to 3 GHz, enabling it to detect electric fields such as those that occur in industry, broadcasting, and telecommunications. Its high sensitivity of 0.2 V/m coupled with its good linearity makes it particularly suitable for checking human safety limit values for the general public. EXAMPLE: E-FIELD PROBE TYPE EF5091 The thermocouple sensors in this probe deliver true RMS results even with short impulses or multiple superimposed frequencies. The 300 MHz to 50 GHz frequency range covers practically everything used...