Improving Combined Version of Current and Charge Integral Equation With Pyramid-Shaped Functions

In this letter, a kind of pyramid-shaped functions is introduced for approximating the electric charge density in the combined version of current and charge integral equation (CCCIE) formulation in low frequency. Since a pyramid-shaped function is associated with a mesh vertex, its total quantity is about half of that of the widely-used pulse functions associated with the mesh triangles for a closed object. As a result, the model of the discretized CCCIE is reduced, significantly. Numerical examples show that, compared with the pulse functions, the pyramid-shaped functions make the CCCIE yield more accurate solutions over a wide frequency range.