Measurement of EMC Emissions from Computers in the Context of the Discussions Regarding the Introduction of UWB (Ultra Wide Band) Applications

In the context on the on-going discussions regarding the introduction of UWB (Ultra Wide Band) devices, this paper presents some measurements results to determine the margin with regard to EMC limits defined by CISPR of a representative set of computers (laptop, desktop, PC under Windows or Mac-OS…). The aim of these measurements is to show that EMC emissions are not present over the whole frequency range and are generally far below the applicable emission limits. The measurements have been performed in a semi- anechoic room following the measurements methods below and above 1 GHz defined by CISPR. Tables summarise the results by giving a list of identified higher emissions together with the corresponding margin with regard to the limit. This analysis has been performed over the frequency range from 500 MHz to 2.5 GHz. The results can be used as a justification for a more severe limit than existing EMC limits applying to UWB applications, because, contrary to the computer emissions shown here, UWB would emit at or just below the applicable limit over several GHz, therefore exhibiting a higher interfering potential towards existing radio services.