Comb generator measurement techniques

Over the past 15 years, comb generators became an indispensable test instrument for EMC labs. Its easy operation led to a wide variety of application like intercomparison measurements of EMC test houses, cable loss measurements and radiated emission system check. The popularity of comb generators should not hide the fact that only the proper measurement know-how can avoid erroneous results. High pulse energy, broadband spectrum and limited frequency accuracy have to be considered when setting the measurement parameters on the EMI-receiver or spectrum analyzer. Good measurement practice is presented by example of cable loss calibration and system check for quality assurance in an EMC lab. The advantage of using an antenna coupler for the system check compared to the monopole antenna is a better repeatability and therefore a more reliable detection of defects (like a broken antenna or cable) in the receive path.