WKES used a digital microwave link for several years. It
was about 34 miles & too low for reliable operation in analog, but worked
very well with digital. The path crossed the McDill AFB at a low level. For a
while, I ran a paper chart recorder of the received signal strength &
noted occasional short pairs of dipped signals, approximately 30 seconds
apart. We assumed this was caused by fighter jets taking off, or landing, in
pairs. These fighter jets used to fly out over the Gulf of Mexico & play
games at super-sonic speeds.
The dips were not affecting our operation, but very
obvious on the chart recorder.