UTD antenna codes through the years

Various UTD (uniform geometrical theory of diffraction) codes have been developed to analyze a wide variety of electromagnetic radiation and scattering problems. The Aircraft Code was originally developed in the early 1970s and initially used a circular cylinder to represent the fuselage. The antenna was mounted on the cylinder and was analyzed using a modal expansion approach. Using this approach, it became obvious that realistic fuselages could not be represented by such a simple structure. This required the development of UTD solutions for antennas mounted on curved surfaces. The first curved surface UTD results were for 2-D cases, which meant that the fuselage could be represented by variable cross-section cylinders, provided they were convex. This improved the aircraft results in the principal plane but did not provide a satisfactory method to treat a volumetric pattern. Through years of modeling a wide variety of aircraft for numerous applications, it was found that a composite ellipsoid was most appropriate in that an efficient geodesic algorithm could be developed, and that it represented the high-frequency radiation properties of general aircraft structures.<>