An implementation of the impedance-boundary combined field integral equation moment method for arbitrarily shaped objects

Impedance boundaries have been used to represent the electromagnetic scattering from various structures such as high-conductivity dielectrics, dielectric-coated conducting objects, and corrugated surfaces. Sebak and Shafai applied the moment method using pulse current basis functions to the impedance-boundary magnetic field integral equation (IB-MFIE), showing that it accurately predicted the bistatic scattering from arbitrarily shaped objects include spheres and cylinders. Glisson [2] used the impedance-boundary electric field integral equation (IB-EFIE) with RWG basis functions to find the backscattering from spheres. The IB-EFIE gave accurate cross-sections with small-radius spheres, but the accuracy was seriously degraded at frequencies near and above the resonances associated with perfectly conducting spheres. Rogers [3] showed that both the IB-EFIE and IB-MFIE are susceptible to the closed-body resonance effects, and demonstrated that the resonances could be prevented by using the impedance-boundary combined-field integral equation (IB-CFIE). Rogers implemented the IB-CFIE only for bodies of revolution.