At same time, it is discussed that the fornded variation-al longitudinal vector function which itseIf or its normal derivative is equal to 0 at the circumforence of S may be expanded by the longitudina1 vector eigen functions of E mede or H mede.

• 同时还论证了在S上有界变去并在周界上为0或法向导数为0的纵向矢量函数可以分别按E模或H模的纵向本征关全展开。