See below.
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk
Rayleigh, Essex UK
On 2018-03-05 18:10, Patrick wrote:
Well, some of us have to consider other requirements, not just EN's.
What if the test is -461, or DO-160 ?
And what if the requirement is 200 V/m ?
As everyone knows, those require a pre-test verification, not a
requirement for "uniform field"?
So a 20% error gives anywhere from 160 V/m to 240 V/m.
JMW: Nevertheless, these are the same dB differences as I posted. If
there is no better solution, increase the field strength until you are
sure it is sufficient. There is no way your are going to finagle the
laws of physics to get closely consistent results in near-field
conditions. You can regard your reported results as 'additional
calibration factors', applicable only to that exact set-up in which they
were measured.
A 600 V/m target is anywhere from 480 V/m to 720 V/m.
Is that insignificant?
Maybe, maybe not.
Depends on you and your customer.
JMW: It's still a range of -1.9 dB to +1.6 dB. If 3.5 dB is crucial, the
product is probably too near the limit for comfort, unless it's a one-off.
I recommend to always check a test labs calibration factors.
If the factors don't show the resonances, then there are built in errors.
An informed decision can be made whether to accept, or move to another
lab.
Would you agree, as an engineer, its always better to have the data,
then to operate in the blind?
JMW: Your minor typo makes that a very profound question. People do
exactly that. They have the data but do not analyse its significance.
This thread is too long, so I have attenuated it.
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