IEEE Std 1502:2007 pdf free download

IEEE Std 1502:2007 pdf free download.IEEE Recommended Practice for Radar Cross-Section Test Procedures.
The dynamic radar can be calibrated using a disposable sphere dispensed from a helicopter or aircraft. The system tracks the sphere and calibrates the system at each frequency used in the measurement. Because measurements can span an extended period between calibration and completion of the mission, the instrumentation radar may require a drift correction system to minimize system drift errors.
3.3 Indoor ranges
Indoor ranges are enclosures lined with radar absorbing materials. The objectives of indoor RCS ranges are identical to those of outdoor ranges, namely to simulate free-space. far-field conditions. The principal advantages of indoor ranges arc as (llows: isolation from weather, immunity from external electronic interference, and physical? visual security. The disadvantages are restrictions imposed by the physical size and cost of the enclosure. Several types of indoor ranges are described in 3.3.1 through 3.3.4.
3.3.1 Indoor compact ranges
The compact range is the workhorse of the modern RCS range indoor facilities. The compact range uses a reflector system to collimate a spherical wave emitted from the feed antenna into a planar wave in a relatively short distance, hence the cerni “compact.” The several types of reflector systems in current use are as follows:
— Offset feed: An offset parabolic reflector with a feed located at the prime focus, but the feed is rotated to “off-set feed’ the reflector.
— Dual Cylindrical: Two cylindrical parabolic reflectors used to create the plane wave. The “folded optics” configuration permits the effective path length to be longer and thus the polarization purity to be improved over the prime focus range. The two reflectors are two- dimensional cylindrical shapes, and thus can be manuthctured at a lower cost, and presence a higher degree of cross-polarization isolation when compared with the Prima Focus reflector.
— Cassegraine dual reflector system: An offset parabolic reflector is fed by a convex-shaped secondary reflector, which in turn is illuminated by a feed. The subreflector can be shaped to optimize the illumination of the main rellcctor and the geometry can be designed to marginally improve the polarization purity.
— Gregorian dual reflector: A type of dual-reflector system that produces a virtual image of the feed at the focus of the main parabolic by using a convex subrellector between the two reflectors to minimize blockage etlects. If designed properly, this geometry provides the best cross-polarization isolation of the three above designs.
The diagrams of these types of compact ranges are shown in Figure 2.