Research On EM Radiation And Scattering Of Complex Objects With Method Of Moments And Its Hybrid Technique With IPO

This dissertation is focused on the radiation problems of various kinds of wire antennas mounted on the complex-shaped PEC platform and the scattering problems of complex-shaped electrically-large PEC targets based on the theory of Method of Moments. With the development of modern antenna technology, a warship is fully equipped with various kinds of antennas working in different frequency bands, which greatly improve the ability of communication, navigation, defence and weapon control. The EMC problems of a warship would heavily threaten the accomplishment of the mission and safety of the vessel itself if it were not settled properly, among which the optimized antenna distribution is the most important one. When antennas are mounted on such platform as a warship or an aeroplane, their EM characteristics will inevitably be changed a lot by the interactions between the antennas and the carrier and that between the antennas themselves. However, the problem of simulation or prediction of EM behavior of onboard antennas is very important and urgent to be solved because the antennas will not function normally when their radiation pattern is distorted severely by the structures around. On the other hand, the RCS parameters of the targets (i.e. warship, aeroplane, etc.) will also meet all the computational difficulties mentioned above.First of all a lot of simple and complex shaped models have been analyzed to check the validity and efficiency of the methods based on EFIE-MoM. A numerical electromagnetic program is developed and its correctness is proved. Geometrical modeling and auto-meshing are made through mature CAD software, which greatly simplify the programming of MoM.Then based on EFIE-MoM, the current computation and scattering problems of arbitrary-shaped complex PEC platform with uniform plane wave incidence are solved.And then the radiation problems of various kinds of wire antennas (i.e. straight wire antenna, helix wire antenna, Koch fractal antenna, etc.) mounted on the complex-shaped PEC platform are solved based on the EFIE-MoM and junction basis function.Finally the scattering problems of complex-shaped electrically-large 2D PEC targets are solved based on the hybrid method of IPO and MoM, which can be easily expanded to the 3-D condition.