Over-the-horizon radar
RADAR SYSTEM THAT CAN FIND TARGETS AT 100S–1000S OF KILOMETRES, BEYOND THE RADAR HORIZON
OTHR; Over-The-Horizon radar; OTH-B; OTH-B Radar; Over the horizon radar; OTH radar; Over-the-horizon; Skywave radar; OTH-SW; ROTHR; Relocatable Over-the-Horizon Radar; Tactical Multi-Mission Over the Horizon Radar
Over-the-horizon radar (OTH), sometimes called beyond the horizon (BTH), is a type of radar system with the ability to detect targets at very long ranges, typically hundreds to thousands of kilometres, beyond the radar horizon, which is the distance limit for ordinary radar. Several OTH radar systems were deployed starting in the 1950s and 1960s as part of early warning radar systems, but these have generally been replaced by airborne early warning systems.