On the Applicability of Numerical Quadrature for Double Surface Integrals at 5G Frequencies

The human exposure assessment to wireless communications systems including the fifth generation (5G) mobile systems is related to determining the specific absorption rate (SAR) or the absorbed power density (APD). The assessment of both quantities requires the use of various numerical techniques, including moments method (MoM). As the use of MoM results in a fully populated system matrix, a tremendous computational cost is incurred, both in terms of matrix fill time and memory allocation, as the matrix size is directly related to frequency of the problem. This paper investigates the applicability of numerical integration at frequencies related to 5G. The novelty of this work is related to the comprehensive set of tests of various combination of source and observation triangles using the developed unit cube test. A number of convergence tests were performed to investigate the effects of the increasing frequency and the discretization scheme on the numerical solution, as well as to determine how to curb the computational requirements by the proficient use of numerical integration. The results show that in the lower GHz range, lower integration orders could be used, resulting in the decrease of matrix fill time without loss of solution accuracy.