An RF power meter has one major drawback: it cannot measure frequency, so it may give an "approved" rating to a defective mobile telephone, as in the following two examples.
功率计的一个主要缺点是：不能测量频率，因此它会对一个有缺陷的手机给出“通过”，就像下面的两个例子。
2
As an example, Finite element analysis and optimization design are made to a voltage transformer of rating primary voltage 35KV, rating secondary voltage 100V, ratingfrequency 50HZ.