Fields of complex surfaces using wire grid modelling

In the resonance range of frequencies, the scattered field from a complex surface such as a ship or aircraft depends on the geometry of the scatterer as a whole rather than on individual scattering centers. Excellent results are obtained by replacing the complex surface with an equivalent grid of wires or wire grid model. The calculation of the currents flowing on the wires of a grid by a moment method solution of an electric field integral equation is summarized. Assumptions made in the formulation lead to modelling guidelines which are local restrictions to the geometry of the wires of the grid. A set of wire grid guidelines or principles to aid in the global design of wire grid models is presented. The objective is an orthogonal grid of square cells of uniform side length. The wire grid guidelines provide a basis for compromise in grid design. They help identify weaknesses in wire grids. These principles are applied to model an ellipsoid and a sphere, with good agreement with measured data, and the exact solution, respectively.