Radiowave propagation in hazardous areas

Radiowaves induce currents in metallic structures and may cause sparking if there is a gap in the structure. The power dissipated in the spark may be sufficient to ignite a flammable atmosphere if the radio wave is strong enough. The author discusses the calculation of the strengths of waves radiated by different types of transmitters. The formulae quoted are to be found in British Standard 6656 and in slightly different form in British Standard 6657. The following topics are covered: properties of radiowaves; transmissions at frequencies up to 30 MHz (vertical and horizontal polarisations); transmissions at frequencies above 30 MHz; microwave antennas; and near fields