On 10/28/2014 2:39 PM, Jim Lux wrote:
For TDR (or looking for integer half wavelengths as you sweep the
frequency on an analyzer) you have to assume a particular propagation
factor,
Mike,
Measuring the length of a long piece of transmission line is tricky for
several reasons, most important because Vf (the velocity factor) varies
a bit with frequency. Study k9yc.com/Coax-Stubs.pdf
An easy way to get close to the actual length is to put a connector on
one end, leave the other end open, and measure the impedance with an
antenna analyzer. At every frequency where it's some odd multiple of
quarter waves long, it will look like a short. So sweep it with whatever
analyzer you own, write down those frequencies, and do the arithmetic.
73, Jim K9YC
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|