RFI Measurements on Free Field Site
Original Publication Date: 1986-Dec-01
Included in the Prior Art Database: 2005-Mar-09
When measurements are made of radio frequency interference (RFI) or electromagnetic interference (EMI) from equipment under test (EUT) on a free field site, it is required to distinguish between signals from the EUT and unwanted ambient signals. Direction finding (DF) techniques with two antennas oriented for minimum response from the EUT are used to identify sources of ambient signals which do not originate from the position of the EUT. Ambient signals from broadcast stations, mobiles, general interference, etc., can be difficult to distinguish from EUT emissions, due to the lack of directivity of a receiving antenna. An existing method used to distinguish equipment signals from ambient signals simply switches off the EUT and note which signals disappear.