what's the radius (inner and outer) of coaxial cable?

Hi, I have a simple question about the coaxial cable model. what's the general dimension inner and outer radius, dielectric constant of the 50 ohm and 75 ohm coaxial cable? Thanks

All basic info on coaxial cables you can find here:
http://www.epanorama.net/documents/w...coaxcable.html
and coax equations:
http://www.phptr.com/articles/articl...&seqNum=2&rl=1
Regards,
IanP

Hey, how can we measure the characteristic impedance of coax cables? Is it possible using measuring instruments ( not ohm meter) ? Like Network Analyser probably?

Magnetra

2 ways.

1) Hook a long length to the two ports of a network analyzer. The input impedance should be 50 ohms. If it is not, the cable is not 50 ohms (it has transformed the 50 ohm load in the network analyzer to some other impedance).

Another way with the network analyzer and a long cable. Hook one end of the cable to port I on the network analyzer. On the other end of the cable put a 10 dB attenuator and either an open or short circuit. Sweep the frequency while measuring S11. The output on a polar display will look like a circle. The center of the circle will be the transmission line characteristic impedance.

2) Get a pulse generator, a fast oscilliscope, a coaxial tee, and a long length of cable. Hook the pulse generator and oscilliscope together with the tee. Hook one end of a long cable to the open port on the tee. Put a 50 ohm resistive load at the far end of the cable. Turn on the pulse generator, and look at its waveform on the scope. After each rising or falling edge, is there a fainter "echo" on the waveform? If so, that is an echo of the pulse arriving at the 50 ohm load and bouncing back. If the cable is indeed 50 ohms, there will be no bounce back at the load.