John (Smith), all you have is a circuit which might light up a couple
of light-emitting diodes from an RF source via a current transformer.
What purpose is served by the 100K resistor is anybody's guess. But it
has nothing to do with SWR.

As Cecil implies, you should go right back to square one and think
about it.

Actually, you are in good company. Most people don't know how their
SWR meter works or what it does. Most people and Tx manufacturers
don't connect it in the correct place for it read SWR on the
transmission line. Consequently it doesn't even indicate SWR and its
name is a very misleading misnomer.

All it indicates is the magnitude of the reflection coefficient of the
load on the transmitter relative to the impedance the transmitter is
designed to see. And it only does THAT provided the meter has itself
been designed to cater for the same impedance. It is fortunate there
exists a standard impedance of 50 ohms.

But don't allow me to put you off. Just obtain a circuit diagram of a
so-called SWR meter (an HF version) from a handbook and, with little
more than Ohm's Law, you can see and work it out for yourself.

Reg, G4FGQ.