LOTHAR-FATT

LOTHAR-FATT (Low probability of intercept Over The Horizon Adaptive Radar - Feasibility Attempt) is an experimental Over-The-Horizon Backscatter (OTH-B) radar operating in the HF band (7–28 MHz). From its quasi-monostatic site in Italy, it provides early warning coverage over a 3,700 km (2,000 NMNM) instrumented range, encompassing Turkey, most of the Arabian Peninsula, North Africa, and the Red Sea. The transmit array consists of 50 broadband quarter-wave antennas arranged in three concentric circles, capable of functioning as a phased array or a Multiple-Input-Multiple-Output (MIMO) radar, with each transmitter using a distinct waveform. This design ensures that individual transmit signals remain below the ambient noise floor, making them undetectable in the area of interest, while the echo signals are correlated by the radar's signal processor using known waveforms. The receiving antenna array comprises 300 active antenna elements, contributing to a 1° beamwidth.

radartutorial.eu: https://www.radartutorial.eu/19.kartei/01.oth/karte019.en.html