CISPR 16-3:2020 is a collection of technical reports (Clause 4) that serve as background and supporting information for the various other standards and technical reports in CISPR 16 series. In addition, background information is provided on the history of CISPR, as well as a historical reference on the measurement of interference power from household and similar appliances in the VHF range (Clause 5). Over the years, CISPR prepared a number of recommendations and reports that have significant technical merit but were not generally available. Reports and recommendations were for some time published in CISPR 7 and CISPR 8. At its meeting in Campinas, Brazil, in 1988, CISPR subcommittee A agreed on the table of contents of CISPR 16-3, and to publish the reports for posterity by giving the reports a permanent place in CISPR 16-3. With the reorganization of CISPR 16 in 2003, the significance of CISPR limits material was moved to CISPR 16-4-3, whereas recommendations on statistics of disturbance complaints and on the report on the determination of limits were moved to CISPR 16'4-4:2007. The contents of Amendment 1 (2002) of CISPR 16-3:2000 were moved to CISPR 16-4-1. NOTE As a consolidated collection of independent technical reports, this document can contain symbols that have differing meanings from one clause to the next. Attempts have been made to minimize this to the extent possible at the time of editing. This fourth edition cancels and replaces the third edition published in 2015. This edition constitutes a technical revision. The main technical change with respect to the previous edition consists of the addition of detailed background information on the large loop antenna system (LLAS) and its measurement method in general and on the models and equations which apply to calculate the reference validation factor and conversion factor curves.