Project Highlight

Propagation & Scattering Group

Developments on novel hybrid methods for large and complex EM problems

The projects covered by this research area are as follows:

P1. Development of an Asymptotic High-Frequency Approximate Solution
The objective of this research topic is to develop an asymptotic high-frequency approximate solution for describing the collective surface fields produced by a large array aperture that is conformal to a smooth convex surface, which is a perfect electric conductor (PEC). The solution describes the fields produced by the whole array aperture, all at once, in terms of just a few surface rays that are launched from specific flash points on the aperture boundary, and propagate along the geodesic surface ray paths to an observation point on the same surface. This solution could be useful for calculating the mutual coupling between conformal antenna arrays located on the same aircraft or UAV, for EMI/EMC applications.

P2. Development of High-Frequency Prediction Code for Complex Targets
The objective of this project is to develop a high-frequency prediction code for modeling EM scattering from complex targets. The target geometry is represented by a computer aided design (CAD) model using triangular facets. TL@NUS will implement the code using the Physical Optics (PO) plus the Physical Theory of Diffraction (PTD), in terms of Mitzner's incremental length diffraction coefficient (ILDC), for calculating the first-bounce incident field contribution which includes the direct reflection and diffraction by the target. The multi-bounce effects will be computed based on the Geometrical Optics (GO) ray tracing combined with the PO approximation. The effects of any coating materials will be taken into account by introducing the appropriate reflection coefficient. An efficient shadowing determination based on the Oct-tree will be implemented.

P3. On the Development, Demonstration and Implementation of New Hybrid Numerical-UTD Techniques for Treating Large Conformal Planar and Curved Antenna Phased Arrays
This is a collaborative project with the ElectroScience Laboratory, Ohio State University (OSU), USA. The principal investigator is Professor P. H. Pathak. The primary focus of this research project is two fold: (1) the first one pertains to the development of a new hybrid uniform geometrical theory of diffraction (UTD)-Method of Moment (MoM) based approach, and an associated code for the efficient numerical calculation of the currents induced on a large planar array of printed/slot elements in a grounded multilayered medium. The electromagnetic (EM) radiation as well as the scattering by this configuration will be computed by this code; (2) the second involves the development of a hybrid numerical-UTD solution, and an associated code, for predicting the radiation by large complex phased arrays embedded conformally on even larger smooth convex metallic platforms such as cylinders, spheroids or even the fuselages of complete aircraft structures that are modeled using canonical shapes.