Design and Manufacture of a Low-Profile Radar Retro-Reflector
THALES COMMUNICATIONS SOMERSET (UNITED KINGDOM)
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A passive retro-reflector can be defined as a device which reflects most of the energy incident upon it in the direction of the illuminator. Radar retro-reflectors are often passive, but active elements can be included to enhance the backscattered signal, or to modify it in some way, such as by the introduction of modulation or simulation of range profiles. Such devices have a significant role to play in the deception of sensors used by adversaries. This paper discusses radar retro-reflectors based on a Van Atta array. First, existing types of passive retro-reflector are compared. The relative advantages of a Van Atta array, a trihedral corner reflector, a Luneberg lens and a sphere are listed. It is demonstrated that, for certain applications, a Van Atta array is preferred. Next, the design of such a device is considered. Parameters discussed are element spacing, type and lengths of connections, and interconnection geometry. A Van Atta array, with a radar cross section RCS of 100 sq m at 10 GHz, has been built and tested. Measurement results are presented, and compared with theory, and with measured data for a trihedral corner reflector with a similar physical size. Finally, possible further developments are described. These include, in particular, the use of amplifiers to enhance the backscatter. The relationship between amplification factor, number of elements, directionality, performance, cost and size is briefly discussed.
- Active and Passive Radar Detection and Equipment