Re: Does anyone have an Agilent 16452A Liquid Test Fixture?
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Hi David,? As I tried to explain in my previous mail, you can not replace the electrodes.? They are fixed in place. The only thing you can change, is the spacer plate between the two halves of the fixture.? So with thicker spacer, the greater spacing between electrodes,? and lower capacitance.?
Regards,? Askild?
On Sun, 24 Oct 2021, 02:04 Dr. David Kirkby, Kirkby Microwave Ltd, < drkirkby@...> wrote: On Thu, 21 Oct 2021 at 09:22, Jim Allyn - N7JA < jim@...> wrote:
?Just poking around the web, I see that the dielectric constant of some liquids varies with temperature and pressure, so you'd want to factor that into your measurements.? (That would be one layer of the onion.)
There’s a document from NPL that discourages the use of the term “dielectric constant”, since it is not a constant, but as you say, varies with temperature, pressure etc. You can’t have a variable constant! The two words are mutually exclusive.?
The correct term to use is permittivity, or relative permittivity. Note it’s a complex number, with a real and imaginary part, with the imaginary part being the loss.
Er = Er’ - j Er”
((Note the dash and double dash).
Yes, I understand the basic way they Keysight fixture works, but I don’t understand how the thickness of the electrodes changes the spacing the way it does. I can’t understand how thicker electrodes results in a wider gap. ?
Dave
Dr. David Kirkby, Kirkby Microwave Ltd, drkirkby@...Telephone 01621-680100./ +44 1621 680100 Registered in England & Wales, company number 08914892. Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United Kingdom
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