A study into the potential effects of ISM emissions on cellular radio equipment

This paper describes the field measurement phase of a study examining the potential for harmonious co-existence between ISM (industrial, scientific and medical) equipment operating within or outside the 900 MHz ISM bands (896 and 915 MHz) and cellular radio systems. These measurements were performed to assess the current levels of emissions from ISM equipment and the form of the “radiation pattern” of typical installations. From this it is possible to estimate areas of potentially poor reception, based on previously-derived protection ratios and assumptions about the location of the nearest base station. This work has been carried out, in part, to help explain the very low number of incidences of interference between ISM equipment and cellular radio equipment, despite the high emission limits set for this equipment in the UK (120 dBμV/m@30 m from the wall of the building housing the equipment)