In message <[email protected]>,
dated Sun, 22 Dec 2013, "ce-test, qualified testing bv - Gert Gremmen"
<[email protected]> writes:
Dirty planes do not exist, unless there is a reference to be compared
to, ideally universal ground.
While most of what you say is true, there IS no 'universal ground', not
even a conducting sheet, if it's bigger in any dimension than about 0.1
wavelengths, and, at lower frequencies, has a surface resistivity larger
than that necessary to reduce the voltage between any two points to a
negligible value. (What is negligible depends on signal levels, of
course.)
The case in this thread is that there was a separate 'chassis plane' in
the stack. In terms of emissions, it's probably misleading to call it
'dirty', but for immunity, it certainly is dirty, because it introduces
into the internal circuits stuff picked up from incident emissions.
With seasonal greetings to all my readers. (;-)
--
OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
Nondum ex silvis sumus
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
-
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