To determine the antenna gain and antenna factor of broadband antennas for electromagnetic interference measurement, we use simple optical fiber link systems. In this paper, we show the time stability and the ambient temperature stability of the simple optical fiber link system for the antenna property measurement. In the case of ambient temperature within 3 degree Celsius, S21 time stability of the simple optical fiber link system is less than 0.1 dB in the frequency range from 30 MHz to 1000 MHz.