The application, design, and performance of over-the-horizon radars

The article discusses over-the-horizon radar systems which can use ionospheric refraction, surface-wave transmission, or high-altitude scatterers as the basic mechanism for trans-horizon propagation. It is noted that the F2 region is usually the principal refracting medium, the F1 region may be used for trans-horizon propagation, and the E-region may be employed for trans-horizon propagation when the radar mission can be supported by reduced-range coverage. Attention is given to the concept of maximum usable frequency and design options for obtaining the required elevation coverage are discussed. Procedures for surface ship detection and missile launch detection are noted.