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Advances in space-based geospatial remote sensing technologies, especially interferometric synthetic aperture radar (InSAR), have enabled precise monitoring of land surface deformations due to geologic and human processes such as earthquakes, volcanoes, and mining. The success of infrastructure monitoring using InSAR techniques is sometimes limited because a distinguishable radar target is not located at the specific point of interest. To overcome this limitation corner reflectors (CRs) are typically employed to provide detectable, measurable targets at the desired locations. However, CRs are cumbersome three-dimensional structures that are difficult to install and align on infrastructure in an inconspicuous manner that also preserve the aesthetic and structural integrity of the installation site. In this research we developed and tested a two-dimensional Van Atta (VA) array retro-reflector to replace the conventional CR in InSAR remote sensing applications. The two-dimensional retro-reflective array can be discreetly flush mounted onto new or existing infrastructure, thereby preserving the aesthetics of the installation site, and will be less vulnerable to vandalism or damage from the elements (rain, snow, wind). A novel antenna element composed of micro-strip patches and Substrate Integrated Waveguides (SIW) was developed and used in the VA array design. Electromagnetic modeling and simulation using the FEKO code was performed to streamline the design process. To investigate array performance versus Radar Cross Section (RCS), a reconfigurable array, based on an elemental (16 x 16 element) array panel, was employed. Increasing or decreasing the number of panels used to assemble the array increased or decreased the RCS. We designed and fabricated nine VA arrays which were assembled into various multi-panel VA geometries. RCS and retroreflective beam pattern were measured in the lab to confirm that they met the design specifications. Field validation was performed on the VA arrays, in addition to a reference corner reflector, custom designed for this project. Multiple high resolution TerraSAR-X satellite images have been acquired, processed, and analyzed using existing COTS software and routines developed at SwRI. Results indicate that the Van Atta arrays are a viable alternative to CRs and can be potentially employed in a variety of applications including military, hazard reduction and climate change.
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