Iranian S-171 stealth drone in blue sky !

[scythian500]

Over the horizon (OTH) radar itself have limitations, notably its size and mobility. Bouncing off the atmosphere is problematic in many ways. For starter, not every frequency can be used, and the bands that are usable can be contaminated by other sources, usually comm radio and TVs, reducing detection accuracy.

So this means OHT are either not a radar or not a radar?

Not all radars are line of sight LOS limited... OTH radars are one example... Other radars that use the ground effect and travel on the surface of the earth is also another example