This publication applies to radio noise from overhead power linesand high voltage equipment which may cause interference to radioreception, excluding the fields from power line carrier signals.The frequency range covered is 0.15 MHz to 300 MHz. The purpose ofPart 1 is to discuss the physical phenomenainvolved in the generation of electromagnetic noise fields; it alsoincludes the main properties of such fields and their numericalvalues. The data should facilitate the use of the recommendationsgiven in CISPR 18-2 and 18-3.