RCS/ISARInnovative Technology Projects Ltd
Basically, RCS (Radar Cross Section) is a graphic representation, or characteristic pattern, depicting the density, of the reflected energy from the surfaces of a scanned target. Sometimes referred to as the ‘target signature’, see the polar diagram Fig. 1.
Fig.1 RCS of a Boeing 777 Scale Model.
ISAR is Inverted Synthetic Aperture Radar, and unlike conventional radar, the target of interest is rotated, and the radar antenna is stationary, pointing in the direction of the target. Fig 2 shows the equivalent ISAR image of Fig 1.
Fig.2 ISAR image of a Boeing 777 Scale Model.
RCS/ISAR Laboratory Scale Model
The Model 8095-50 Radar Cross Section (RCS) and Inverse Synthetic Aperture Radar (ISAR) Measurement System Fig.3 is a sophisticated pulse-mode RCS training and measurement system that has been specifically designed for operation at close range. The Model 8095-50 is a low-power modular system that operates safely in classroom or lab environments.
The system can produce radar cross section (RCS) patterns of targets of up to 75cm length when using its 5ns pulse-width. The system can also generate high resolution ISAR images of much larger targets when used at its smallest pulse width. It operates over a frequency range of 8 to10 GHz.
Fig.3 RCS/ISAR Laboratory Training and Measurement System
In ISAR mode, range and cross-range resolution are 12cm for a maximum target length of 2.44m. Cross-range resolution can be improved with targets of reduced lengths.
Because the system is based on pulse operation, it does not need to be operated in an anechoic chamber, or in an outdoor range. Background clutter is rejected by time-gating and by additional background subtraction during the measurement process.
The system uses a low-RCS target support to achieve precise RCS measurements, and a high-quality PC pre-loaded with the RCS processing software and the necessary I/O boards.
A range of scale models which have been used with the system include-
- Boeing 777 Commercial Airliner
- F117 Stealth Fighter
- B2 Bomber
- Frequency 8-10 GHz
- Antennas 18 dB (7.3 x 9.1 cm; 2.9 x 3.6 in) pyramidal horn
- 27 dB (30 cm; 11.8 in) offset feed parabolic reflector
- Sensitivity -37 dBsm
- Pulse Width variable from 0.6 to 5.5 ns (1,2 and 5 ns in calibrated mode)
- Peak Power 200 mW
- Range up to 10 m; 30 ft
- Dynamic Range 54 dB
- A/D Conversion 10 bits
- Averaging 4, 8, 16, 32 samples
- Positioning Accuracy 0.25 degrees