www.radartutorial.eu www.radartutorial.eu Card Index of Radar Sets - Air Defense Radar


Description of the radar set, tactical-technical characteristics
Alenia RAT-31SL
(click to enlarge: 480·640px = 53 kByte

Figure 1: Alenia RAT-31SL 3D- Early Warning Radar

frequency: S-Band
pulse repetition time (PRT):
pulse repetition frequency (PRF): (staggered)
pulsewidth (τ):
receiving time:
dead time:
peak power: 155 kW
average power:
instrumented range: 250 NM
range resolution:
beamwidth: 1,5° (1,3°)
hits per scan: 1 to 3;
antenna rotation: 10 s


RAT-31SL (original manufacturer's designation: MRCS-403) is an S-Band 3D air defense radar using a phased array antenna. It is designed for target acquisition and fighter control, and can detect and track targets up to a distance of 450 km.

The RAT-31SL is a state-of-the-art system designed to operate in modern complex military air defence and air traffic control systems. Sophisticated technology allows the RAT-31SL to rapidly adapt to a broad spectrum of changing operational scenarios where jammers coexist with heavy clutter. The RAT-31SL 3D early warning radar uses multiple simultaneous independently phase controlled pencil beams that provide flexibility in scanning and very high data rate that is effective for clutter processing.

Each beam provides monopulse altitude measurements with excellent accuracy even in the frequency agility mode. Reduced peak power provides resistance against ARM (Anti Radiation Missiles) and ECM.

Fixed and adaptive notch MTI filters are enabled by continuously updated maps to optimize the performance for ground and sea clutter, rain, chaff and clear conditions. Excellent ECMs are assured by the very low sidelobe antenna, reduced peak power, frequency agility, jam strobe reporting and a separate receiver for ECM monitoring. The mechanical configuration has been designed to facilitate assembly/disassembly an the battlefield in order to provide an increased survivability through relocation.

Primary Antenna

Type and Scanning:
corporate rear feed planar-array
 with electronic scanning in elevation and
 mechanical rotation in azimuth
Elevation scanning: 0° to 20°
Polarization: Linear/Horizontal
Beam pattern: Pencil beam
Target Altitude measurement: monopulse
Rotation speed: 6 r.p.m.

Type: Coherent chain
Final stage: TWT
Driver: solid-state
Peak power: 155 KW
PRF: Staggered

Type: Double conversion superetherodyne
RF receivers: Dual matched
Frequency selection: Manual, random, automatic
Adaptive Clutter Attenuator: IF STC with steps controlled in azimuth and range
IF receiver: Linear
pulse compression: SAW matched filters, FM chirp in Long Range channels and digital for high PRF channel

Signal Processor
Type: Digital with in-phase and quadrature processing
Anticlutter filters: adaptive notch MTI cancellers, Fixed and real-time automatic clutter mapper
azimuth correlator: Moving window type
Amplitude detectors: Digital modulus extractor

Alenia RAT-31SL TWT-Transmitter cabinet
(click to enlarge: 800·600px = 80 kByte)

Figure 2: Alenia RAT-31SL
the TWT-Transmitter cabinet