Cec, you have YOUR explanation and I have MY explanation.

Which is the most simple?

There is a bridge.

When the variable arm, the load, is 50 ohms the bridge is balanced and
the meter indicates SWR = 1:1

When the variable arm is either 0 ohms or infinite ohms, the meter
indicates SWR = infinity :1

What can be more simple than that? How it works can be visualised.

But the meter is ambiguous. It cannot distinguish between loads of 0
ohms and infinite ohms. Additional information is required.

This serious ambiguity also applies to your weird contraption. ;o)
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Regards, Reg.