02 February 2015 11 9K Report

Hello.

There is an instument with HighZ load and this is connected via 50 Ohm BNC cable to Oscilloscope(OSC) with several impedance selections (HighZ, 75 and 50 Ohm).

People say I can choose 50 Ohm as OSC impedance then no reflection but huge attenuation of signal from the instrument is expected. Attenuation is understood as this is similar to a voltage divider but why is there no reflection without perfect impedance matching?

They also say that adding load terminal ub type with BNC tee or just in-line type) to the end of the cable at source side can control impedance matching. How? The impedance of the source, cable and OSC are already determined. How can adding load between source and cable help to match the impedance?

Lastly it looks like stub and in-line type of the load have different circuitry. Thus which is the best choice?

Please see the link where you can see the load terminal and what I meant.

https://www.thorlabs.de/newgrouppage9.cfm?objectgroup_id=7312

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