I tried out this website but don't understand the fifth box labeled "eR".
"eR" is a new term for me; is it perhaps a microwave term?
"eR" remains unchanged when any of the other boxes is changed, so it seems to be an input value.
I tried various values to see if I could discern the meaning but that didn't work, so I'm stuck.
Also experimented with clicking the box "Show two interfaces" and that didn't help either.
73 Jerry KM3K