Measurement of radar horizon in a real marine environment and its influence on the reduction of interferences

Coastal electromagnetic environment is increasingly complex. The emergence of cellular telephony provides important spectrum occupancy at 900 MHz frequency band. Radar systems are essential tools for the detection of targets at the sea, and in a tactical scenario nearby onshore, it is extremely important that they remain unaffected by the existent electromagnetic pollution. Despite most radar systems operate at frequency ranges from 2 GHz to 40 GHz, low-frequency radars at ultra-high frequencies might fall within GSM/GPRS 900 MHz frequency band, where the cellular network generates a strong interference and a desensitization of the radar by the external noise produced by the coastal base-stations. This work shows that the approximate limit of these mutual interferences is the radar horizon, analyses the degradation in terms of probability of detection and range performance, and demonstrates how radar horizon can be used as a reference to mitigate such interferences. The analysis presented herein is based on a real measurement campaign carried out at Cádiz Bay, Spain.