[BC] efficiency vs height

[Clive Warner]

recalling the recent discussion on too-high (as a fraction of lambda)
towers, I was interested to see in my copy of "Long Wave and Medium Wave
Propagation" (BBC Engineering Trainining Supplement no. 6), a graph.
The really noticeable item is that maximum ground wave radiation is given at
0.63, but it falls away to 40% by 0.8, and to 20% by 0.85 and to *nothing*
at 1.0 lambda.
Whereas the penalty for running 0.125 is about 47%
- Clive