I never thought about coax having a low frequency effect, but makes sense.
Twisted pair telephone wire is considered to be 600 - 900 Ohms with a large
capacitive component at voice frequencies, by 25KHz it is about 135, and at
T1/E1 frequencies, which are over 1 MHz, about 100 Ohms.

Tam/WB2TT
"Reg Edwards" wrote in message
...
For anyone who may be interested.

Typical of RG-58 and RG-11 type cables.
Zo = Ro - jXo
Xo is always negative.
Angle of Zo in degrees. Always negative.
VF = relative velocity.

Freq Ro jXo Angle VF
------ ------ ------ ------ ------
50 Hz 967 -965 -44.95 0.034
1 kHz 220 -213 -44 0.151
10 kHz 80 -58 -36 0.41
100 kHz 56 -9.3 -9.5 0.59
1 MHz 52.4 -2.4 -2.7 0.63
10 MHz 50.7 -0.76 -0.86 0.65
100 MHz 50.2 -0.23 -0.27 0.66

Smith Chart calculations begin to be inaccurate around 2 MHz and below.
So
do SWR meters.