HFSS中如何设置有耗地面半空间的问题

HFSS里面想算有耗地面的半空间问题，我可否通过如下设置来达到：
在一定的空间内将底面设置finite conductive boundary并勾选infinite ground plane,其它面设置为辐射边界条件。
现在我有个问题，就是这种有限电导率地面是会延伸至无穷大吗，还是只将边界内的地面看成是有耗的?
像积分法，就可以将损耗计入格林函数来计算 ，不需边界条件
HFSS的帮助文档是这么说的：
Lossy ground planes may be approximated by selecting the Infinite ground plane check box when assigning a finite conductivity or impedance boundary. The effects of these boundaries are incorporated into the field solution in the usual manner, but the radiated fields in the 3D Post Processor are computed as if the lossy ground planes were perfectly conducting.
它说在算辐射场的时候地面还是算成pec，前一句话红色字，那两个词组是啥意思，场解是具体指的算什么，usual manner又是说的什么方式，太简略了都看不太懂，还请达人指点一二啊