Design and Optimization of Radar Systems to Assist Rotorcraft Piloting in Adverse Environments
Navy SBIR FY2008.2

Sol No.: Navy SBIR FY2008.2
Topic No.: N08-141
Topic Title: Design and Optimization of Radar Systems to Assist Rotorcraft Piloting in Adverse Environments
Proposal No.: N082-141-0010
Firm: Delcross Technologies, LLC
2009 Fox Drive
Unit K
Champaign, Illinois 61820
Contact: Bob Kipp
Phone: (312) 431-7413
Web Site:
Abstract: Rotorcraft are increasingly turning toward high-resolution Ka- through W-band radar sensors that can image terrain and obstructions but also see through the particulates that confound infrared and optical sensors, such as sand, ocean spray, and fog. As with any onboard sensor, designers must consider the antenna/platform interaction, and mature tools exist to address this type of problem. However, at these wavelengths, airborne vehicles can span several thousand wavelengths. This is well beyond the capability of any full-wave electromagnetic solver. While asymptotic techniques are practical here, they are powerless to model the antennas, themselves. We propose to investigate two novel techniques for integrating asymptotic and full-wave methods that can solve the end-to-end antenna/platform integration problem. One technique folds physical optics directly into method-of-moments to greatly expand the size of problem it can handle, but without compromising accuracy. The other splits the problem into small (full-wave) and large (asymptotic) regions, the novelty being the ease of integration that allows both solution regimes to fully couple. Phase I will focus on proof-of-concept and comparative evaluation of these two techniques. In Phase II, the more promising technique will be selected for full development, including a commercial-grade GUI.
Benefits: Improvements in millimeter wave electronic components have facilitated a general trend toward radar sensors and communications equipment that operate beyond X-band. There are several motivations for this that ultimately stem from the shorter wavelengths employed: smaller antennas, lighter weight, higher-resolution imagery, more directional and higher gain antenna beams (improved covertness), less crowded spectrum, and larger bandwidths. Hence, at a time when full-wave electromagnetic (EM) solvers running on high-performance super computers are just beginning to crack the X-band barrier for aircraft-sized problems, the bar is being moved to significantly higher frequencies of Ka- through W-band (i.e., 18 - 111 GHz). Although modern full-wave codes have better scaling properties than their predecessors, analyzing most airborne and ship platforms at these higher frequencies with purely full-wave tools based on current accelerations techniques will remain completely impractical for the foreseeable future, especially for the great majority of analysts who lack routine access to super computers. Asymptotic methods (e.g., ray tracing codes) remain the relevant approach for these platform scales and frequencies. However, it is well known that asymptotic tools are not able to solve the EM problem from end-to-end, starting with the antenna itself, as these are resonant structures that require a full-wave treatment. Usually, this is addressed through a simple and practical hybridization scheme, colloquially known as "A + B", where the small to moderately sized antenna is measured or simulated with a full-wave code, and these results are then fed into the asymptotic tool. However, this approach is powerless to capture the influence (i.e., loading) of the electrically large platform on the antenna, which is often significant. Researchers have published more sophisticated hybrids that include partial or full coupling, but these remain boutique capabilities because their full-wave/asymptotic interfacing requirements are far too burdensome and error-prone for the typical end user. The chief technical benefit of the proposed Phase I research is the development and demonstration of two highly novel full-wave/asymptotic hybridization techniques that can solve the end-to-end problem at these frequencies without over-simplified coupling between the solution regimes. One technique offers full-wave-like accuracy to these very large-scale problems. The other technique introduces a novel interfacing approach that allows the full-wave and asymptotic solutions to fully couple, but without introducing significant and error-prone setup burden upon the end user. The main benefit of the Phase II project will be the development of a commercial-grade code that embodies the more promising of these two techniques. Given the trend identified earlier, there is a great need in both commercial and military sectors for physics-based installed antenna simulation tools that can operate at Ka- through W-band. The impact of antenna installation on realistic platforms is almost always significant, and simulation, while ultimately no substitute for measurements, is much more cost-effective and flexible for design trades. Also, recognizing the increasing use of radar sensors in these bands, the proposed techniques are also directly relevant to the problem of predicting platform radar signatures at these frequencies. Hence, we believe the simulation tools and technologies arising out of the proposed research have significant commercialization potential in both military and non-military system engineering markets.