Read other posts in the “Elephant in the Test Room” series here.
I apologize for the prolonged absence, my attention was drawn elsewhere for a while – back in the saddle now for the foreseeable future at a rate of at least one blog post per month.
Anonymous says
Hmmm so if I understand correctly you would prefer an antenna system coupled to an , lets say Spectrum analyzer, and validate , calibrate the field this way iso of with a field probe. I have one comment only on the whole subject of immunity testing. The real world environtmental RF conditions that cause real problems with Objects be it equipment or otherwise can't be replicated or used for testing due to cost and time consuming reasons. So our testing is already compromised by the real world why bother with the harmonics (just joking)
Anonymous says
Hi Tom, This is why some amp manufacturers are looking towards solid state, with the decreasing cost of solid state devices it's getting such that there is very little difference between the two technologies. There is actually a way round this problem. We have advised that it is always possible to conduct your sweep from HF down to LF, TWT's have very little radiation outside their operating bandwidth so the potential for misleading harmonic interference goes away.
You do always have the potential problem in 2 signal mixing products within the EUT but that's a different story!
Best Regards
Tim Hague
European Technical Manager
AR Europe.
Anonymous says
I beg to differ. I agree that there are elephants in the EMC world but harmonics from a TWT should be removed by band pass (or low pass)filters. As in your example a 1-2GHz amplifier should be fitted with a 2 GHz low pass filter to reduce the level of the harmonics. We 1-6 GHz TWT that has high harmonics but a 2,4,6 GHz low pass filter to connect to the same amplifier. It is just a matter of doing it right