Investigation of two formulations using curl-conforming basis functions for the MFIE

The magnetic field integral equation (MFIE) is widely used in method of moments (MoM) for electromagnetic scattering analysis of arbitrarily shaped three-dimensional conducting objects. Besides the well-known Rao–Wilton–Glisson (RWG) basis functions, the curl-conforming n×RWG basis functions are also used in MFIE to improve its accuracy. However, there are two different impedance matrix element formulations that result from the use of the n×RWG basis and testing functions to the MFIE in the literature. Moreover, one of the formulations is more complicated than the other. This stimulates us to explore which formulation is more efficient in improving the accuracy of the MFIE. This paper investigates the efficiency of two impedance matrix element formulations resulting from the use of the curl-conforming n×RWG basis and testing functions to the MFIE. Details to calculate the impedance matrix elements are studied. Numerical results show that the radar cross section (RCS) results of the first formulation are more accurate than those of the second one while consuming only about half of the time to fill the impedance matrix for the second formulation. Thus, compared with the second formulation, the first formulation resulting from the use of the curl-conforming n×RWG basis functions to the MFIE is a better choice for scattering analysis of three-dimensional conducting objects.