I've been looking for a source, but I remember a previous air show incident where a stealth aircraft was detected and the excuse was that the active stealth sys

I've been looking for a source, but I remember a previous air show incident where a stealth aircraft was detected and the excuse was that the active stealth system was not turned on, i.e. the aircraft would have used electronic active radar cancellation in addition to stealthy body design if it had been in actual combat. Whether any electronic system would help against passive radar, or would in fact make things worse, is another question.