Can someone tell me why high frequencies (1 MHz sine signals) are getting attenuated in the below case.
- I have a function generator with 600 Ω output impedence. I connect this output to a digitiser channel input of input resistance 1 MΩ. I connect this via a 30 m BNC cable(https://in.element14.com/belden/9222-004100/triaxial-cable-rg-58a-u-50-ohm/dp/1288489).
I can see that at high frequencies (1 MHz) the voltage of the 1 V input reduced to 200 mV.
So I decided to simulate the above setup in LTspice and got almost the same behaviour. If we replace the transmission line with a wire connection there is no attenuation.
Why does this happen?