Art Unwin wrote:

...
2 elements required? What does that mean?

There ya' go ... his response.

It appears, what he was saying was/is, you cannot obtain maximum
transfer of power to the antenna with the variometer alone--you must use
a pi/LC/etc. (a capacitance in conjunction with an inductance) ...

I re-read his post, that meaning was implied well--but I could only see
it with hindsight.

JS