Sommerfeld型广义积分和近距离地面场强

Approximation expression of ground-wave field intensity at short range from the vertical element over the flat earth

Sommerfeld型广义积分在电磁理论、天线与电波传播技术中是非常重要的,一般采用数值或解析方法计算,但数值计算在近地面时会遇到收敛慢的问题。本文通过分解反射波谱密度函数及级数展开等技巧,导出了求解垂直点源近距离地面反射场时遇到的一些Sommerfeld型广义积分的解析表达式,并给出了近距离场强的近似表达式。该场强表达式简洁且是解析的,在实际工程计算中有重要的应用价值。

The solutions of Sommerfeld type integrals,which are vital in the domain of electromagnetic theory and antenna and propagations, may be given by analytic equation or numerical method, however, the digital approximation is very slow at short range. In this paper, the analytical expression is derived for some of the Som- merfeld type integrals which appear in the expression of the reflected field-strength of the vertical element over the flat earth by decomposition reflected field intensity and series expansion, and the approximation expression of the ground-wave field at short range, where the residue series converges slowly and the geometrical optics is inadequate, from the vertical element is derived also. This expression is concise and analytic, and is of significant application value in engineering calculation.