The Scale Relation Of The Composite Electromagnetic Scattering From A Conductor Target Above Sea Surface

Studying on the electromagnetic scattering from targets over sea background provide a theory support for precision-guided, target identification and stealth technology. The calculation of Radar Cross Section is a popular and important problem in engineer, so only theory calculation is not enough and measurement is needed. Scale technology is applied popularly because it can make measurement easier. Based on two high frequency approximation method, Physical Optical method(PO) and Equivalent Edge Current method(MEC), the Radar Cross Section(RCS) of a missile with empennage and without empennage is calculated to analyze the influence of diffraction field from the empennage. The scale relation of electromagnetic scattering from electrically large target is given based on the method of equivalent edge currents which considers the influence of edge diffraction. To verify the validity of the scale relation proposed, the bistatic radar cross section of cube and trapezoid are calculated. Numerical results confirm the validity of the scale relation. The scale relation of coupling field from 2-D sea surface and a 3-D conducting object is given based on MEC and the Lorenz’s reciprocity theorem, a trapezoid over sea surface is calculated to confirm the validity of the scale relation.Modeling simple targets like cone, cylinder, cone cylinder with FEKO and modeling complicated target missile with 3DMAX or Auto CAD. Using PO to calculate the RCS of those targets and comparing the PO results with the commercial software FEKO. Comparing results show that the PO method is efficient. Considering diffraction field, EEC method concluding POEEC and PTDEEC is introduced with emphasis. The method is used to calculate 3-D target. The RCS of targets is calculated using EEC. The EEC result is compared with PO to analyze the influence of diffraction field.Based on the similarity, the scale theory of electromagnetic scattering of perfectly conducting is introduced. The electromagnetic scattering of nonmetal loss dielectric is further discussed. Then the inconsistent among scaled measurements of RCS in microwave band is introduced simply. The scale relation of scattering from convex body is also given, based on KA. Finally, discussion is focused on the scale relation of targets with edges. The scale relation is given based on EEC and confirmed using a cube and a trapezoid. Based on the general scale theory, the scale relation of 2-D rough sea and ground surface is given, and they have been confirmed by modeling the sea and ground surface model. Based on KA, SSA and SPM the scale condition of electromagnetic scattering from rough surface is given. The scattering coefficient of sea surface in the condition of different wind speed and different frequency is given to analyze the inference of speed wind and frequency.The reciprocity theorem that is used to calculate the composite scattering from rough surface and target is introduced. Combining EEC method with the reciprocity theorem, the composite scattering from 2-D surface and 3-D target is calculated. At last, the scale relation of coupling field from target and sea is derived. To verify the validity of the scale relation proposed, the coupling field from a trapezoid and sea is calculated.