用cst的rcs模板时，网格数与不用模板时不一样

计算1cm金属球的RCS，仿真频率5G-6G。尽管先设置了工作平面的大小为5mm,但是设置完频率后，工作平面自动更改,如果改小的话会提示 the selected working plane size is smaller than the structure. the word plane will automatically be extended to the structure size. 为什么?
用RCS模板的计算区域要比不使用RCS模板的计算区域大，在相同网格划分参数条件下，有更多的网格数，使用RCS模板是11664个网格，不用的话是6750个，不用RCS模板的划分结果要更细。

加一句，如果更改仿真频率的话，工作平面的大小也会自动调整。好奇怪啊?对结果会有影响吗?

The default minimum distance of the "open add space" boundary is 8-th part of wavelength, which is based on the center simulation frequency. Therefore, when you change the simulation frequency range, you have changed the center frequency, then the distance of the boundary will be adjusted afterwards.