Abstract: The vector network analyzer can be applied to directly measure the scatter parameters of two-port microwave devices.The time domain technique of the vector network analyzer was useful for identifying discontinuity.But how to set measurement parameters such as frequency band,points,window functions and so on was much more difficult for microwave engineer.This paper showed the time-domain methods and theories.The open standard was measured for describing some problems of time-domain.

Key words: Network analyzer, Time domain measurement, Open standard