“...along with troposcatter radio (signals are sent straight up, and they bounce off the troposphere back to other radios) to connect EPLRS units that are not within line-of-sight of each other. As the marines discovered, this works quite well.”
Sounds like NVIS transmissions on the 40 meter band (Near Vertical Incidence Skywave). It works quite well over 500 or so mile range with no coverage holes.
Unless, the Tropo systems the marines use are very different than the ones the army use, they do not point them straight up, it woul defeat the purpose. You have to angle bounce the signal off of the troposphere, and it a rather narrow angle, using hyperbolic antennas.