Re: Does anyone have an Agilent 16452A Liquid Test Fixture?
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On Tue, 26 Oct 2021 at 02:21, Jim Allyn - N7JA <jim@...> wrote: On Sat, Oct 23, 2021 at 05:03 PM, Dr. David Kirkby, Kirkby Microwave Ltd wrote: "The United States and Great Britain are two countries separated by a common language." The term "dielectric constant" is widely used in the UK, so it's not just the USA which uses it. However, if you think about it logically * Pi is a mathematical constant (3.14159..). * c is a physical constant (299792458? m/s, which is approximately 3 x 10^8 m/s) * something that changes can not be a constant. Science and engineering advances, and just because we have always done it one way, does not mean we should continue to do it that way. NPL's argument for discouraging the use of the term dielectric constant is to discourage people from thinking they are measuring a constant. If you accept that relative permittivity is a better term, you can then, when appropriate, mention it is actually a complex number. The relative permittivity Er of a material is a complex number, normally written with a dash and double-dash like Er = Er' - j Er'' where the Er'' is the loss term ? Just because * you Americans have used the term "dielectric constant" for years * I myself have used the term "dielectric constant" for use * many Brits have used the term for years does not mean we should continue to use such a term, when someone points out that it is not a constant but a variable. Feel free to continue to call this variable a constant if you wish - many Brits will no doubt do it too. But this particular British person is not a stick in the mud. Dave G8WRB |
Dr. David Kirkby, Kirkby Microwave Ltd