RF/Microwave Power Measurement Uncertainty

[Ruebenn]

Dear All,

I have scoured some technical websites for some help on the measurement uncertainty of RF/MICROWAVE power measurements.
I Gather that there are 2 general methods..there is one which is the ANSI method and the other the standard ISO method?
Can i choose the former method to derive my uncertainty for the measurement of RF/MICROWAVE power if i am comfortable with it?
Would i be going against the ISO17025/ISO GUM rules?

Rgds
Ruben

[Hershal]

You may be able to use the ANSI method, but still need to consider the various effects because you need to know what your uncertainty contributions are and what they are doing to you.

In particulare, look for mismatch loss, VSWR, Rho and Gamma of both the source and load, and depending on your conduit you may have surface loss to consider. A modern analyzer can help with the calculation of most of that, so you don't have to break out the Smith charts, but you may still have to calculate mismatch loss and VSWR.

Depending on the frequency and power you are working with, additional influences may also come in, but the listed ones will do to begin.

Hope this helps.

[Ruebenn]

Dear Sir,

Thanks for the help.
The ANSI method gives me a better approximations at certain power levels but the ISO method does the same at some levels as well.
I am in a fix to use which method so that i can finalize my documents.
Is it a sin to have to methods of calculation uncertainties over at different levels as per the ISO 17025 requirements?
Anyways, calculation wise - i think both is not a bother as i think have already covered more parameters in the budget( i am thinking to drop some parameters(budget)to come up with a better BMC) BUT I AM JUST WORRIED SO AS TO COMPLY TO THE ISO 17025 requirements, thats all.
Anyways, thanks for the help.
Appreciate the help.

Rgds
Ruben

[Ruebenn]

Dear Sir,

Can you tell me what is the SI unit of amplitude modulation?
Also the frequency and phase modulation as well?
I wish to know how to put them in the S.I units?
I know all the units are in Hz..hertz over Hertz cancels off leaving a relative value, true?

For the calculation of amplitude,phase and freq modulation using the 8902S system,
it is stated as 3% + 1 digit (what is the digit here- is it the noise floor,resolution or what?)

Appreciate the help.
Also when i state my bmc for the tuned rf level for a certain range..
say for an example my bmc for a tuned rf level measurement from the range 0dB to 10 dB is 0.03 dB,
what does this mean?
Does it mean 0.03dB of the range or the reading?

Rgds
Ruben