The other point I note is that he wants enhanced HF radiation between
10 and 4 degrees elevation and apparently beamed to a specific point
on the globe... The cubic size and the towers and the arrays that it
will take to accomplish this are not efficient in time, money, and
effort... He is chasing a unicorn...
As has been pointed out already, the percentage of time that the major
portion of the arriving HF EM wave is below 10 degrees can be
enumerated on the fingers of one hand... Besides, who is going to have
the array on the other end with comparable response?

denny / k8do