High Frequency Signals & BNC Cables: Explained

[cks]

Hihi,

I don't understand what is the meaning that BNC cable transfer high frequency signal?

For example, I use BNC cable for the connection between my diode controller to the diode laser. I also use BNC cable to connect my photodiode to the oscilloscope.

I'm not sure what is the meaning of high frequency signal here? Is the signal transmitting has high frequency? but the voltage to my diode is a direct current, so where comes the frequency?? a bit confused.

I know the BNC cable can shield away from picking up radio signal and antennas from somewhere else, but what is high frequency mean here? Can it transmit low frequency?

 

[berkeman]

Coax can be used from DC to its cutoff frequency, although its loss can be significant well before its cutoff frequency.

Twisted pair makes a fine transmission line too, but does not have the self-shielding feature of coax.