ARSR-4

The ARSR-4, also known by its military designation AN/FPS-130, is a coherent, three-dimensional, solid-state, L-band (1215-1400 MHz) long-range surveillance radar designed for air traffic control. Manufactured by Northrop Grumman in the United States, it features a wideband antenna with dual stacks of elevation beams for optimized time-energy management and reduced false targets, achieving azimuth sidelobes below -35 dB and utilizing circular polarization for enhanced aircraft detection in adverse weather. Its solid-state transmitter employs intrapulse non-linear frequency modulation (NLFM) with a 150 µsec pulse divided into two sub-pulses (90 µsec and 60 µsec) transmitted at different carrier frequencies for frequency diversity, delivering a peak power of 65 kW and an average power of 3.5 kW. The system provides an instrumented range of 463 km (250 NM) with a range resolution of 323 m, and an antenna rotation speed of 5 rpm with a beamwidth of 1.5 degrees. Accuracy is specified at 116 m (1/16 NM) in range, 0.176 degrees in bearing, and 914 m (3,000 ft) in height, with eight pulse Doppler filters suppressing clutter up to 400 km. The modular digital target extractor and tracker can process 800 aircraft and 200 non-aircraft reports per scan, with expandability and a 50% reserve capacity, while the integrated ATCBI-6M secondary radar is compatible with ICAO, ATCRBS Mode S, and military IFF Mode 4. The ARSR-4 also provides six levels of weather processing, and its design, featuring a transmitter located below the rotary joint, automatic reconfiguration, reserve capacity, and redundancy, ensures high availability and allows for repairs during operation. The system is designed for unattended operation with remote control, monitoring, fault detection, and analysis, and 44 units are deployed along U.S. borders and coasts to track en route air traffic.

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