RF cables

Thread Starter

kubeek

Joined Sep 20, 2005
5,718
Hi,

can anyone tell me approximately on what frequency does for example a 50ohm coaxial cable start to act as if it has some impedance, and stops behaving like two pieces of wire?

Also I am not exactly sure how would I measure the impedance, if I had a signal generator?
 

beenthere

Joined Apr 20, 2004
15,819
If you are transferring power, there really isn't a lower limit. A 50 ohm transmission line is resonant with any frequency applied. It just makes a low loss path between resonant structures.

That 50 ohm characteristic is always there as long as it is transmitting power.

You measure indirectly, by comparing the power in your RF output stage and the power developed in a dummy load. Any difference is what got lost in the transmission line and connectors.
 
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