What is the approximate maximum range for signals using transequatorial propagation?

Transequatorial propagation (TEP) involves radio waves refracting off highly ionized regions of the F-layer located approximately 15 degrees north and south of the geomagnetic equator. The geometry of this double-refraction without an intermediate ground reflection creates a very specific optimal path length. Because stations must ideally be located about 2,000 to 2,500 miles away from the equator on either side to hit these ionized zones at the correct angle, the total maximum range for a TEP path is approximately 5,000 miles. Distances much longer than this cannot be supported by a single TEP hop.