"Jeff" wrote in message
...

Connector impedance doesn't change with frequency, just as coax
impedance doesn't change with frequency. Loss will increase as
frequency increases, however.

Coax impedance certainly does change with frequency. Below about 500kHz
there is a significant slope with frequency.

At 200kHz a 50ohm cable may well look more like 100ohms and by the time
that you get to 1kHz it could be as high as 1kohm.

200kHz is in what is called the transition region and the impedance is
given by:

SQRT((R+j2pifL)/(C+j2pifC))

as opposed to the high frequency region where it is merely:

sqrt(L/C)

Below about 20kHz it changes again to SQRT(R/(j2pifC)

There are also other variables due to changes in the dielectric with
frequency and other losses.


Thanks for this Jeff. That is the first time I have seen anything about the
impedance other than formulars that just compair the diameters of the
conductors and modified by the dielectric. There was never a mention of
frequency affecting the impedance.

I guess that it is like many other electrical/electronic formulars. They
leave out some of the 'small change' . Sort of like what I always referr to
as putting one extra brick on a truck load . Just too small to worry about
in most cases, but it is still there.