Re: Inductance at High Frequency

Jian wrote:
> 
> If I know L and M at low frequcy,
> how to calculate the L(f) at high frequcy?
> 
> Take an simple example:
> 
> ---------- L
> M
> ---------- L
> 
> 2 straight wires of length l, radius r, self-inductance L
> and mutual inductance between two M at low frequency.
> 
> L(low f) = L +- M
> 
> How to calculate L(f) at say 50-100MHz?

Same theory. Some factors that can be ignored at 50/60 Hz become
important at higher frequencies. The conductor skin effect, for
instance.

In addition to the inductance, you will have to consider capacitance as
well. This will have a significant effect on the overall impedance of
the line. It might be a good idea to look at the parasitic losses of
insulators as well. Materials that appear to have certain properties at
LF behave differently at RF.

You might also want to look at the behavior of the lines in terms of RF
radiation. This usually isn't a concern where 1/2 wavelengths are
hundreds of miles long at 60 Hz but it will be an issue now. Some of the
math for this may be easier to find in RF handbooks rather than power
systems texts. 

-- 
Paul Hovnanian     mailto:[EMAIL PROTECTED]
note to spammers:  a Washington State resident
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Have a pleasant Terran revolution.