An Evaluation Method of Vehicle Radiation Emission Measurement System in SAC

Vehicle radiation emission is usually tested in a semi-anechoic chamber (SAC). The measurement system including the test site, the measurement receiver, the antennas, the connection cables, and other items within the test site, will all affect the measurement results. In the daily work, it is not convenient for the laboratory to confirm the normalised site attenuation (NSA) of the SAC by comparing it with that of the open-area test site (OATS) before each test. In order to guarantee the accuracy and consistency of the measurement results, a method using a comb signal generator as a reference radiation source is presented in this paper. And the maximum limit and minimum limit of the reference generator's radiation emission are obtained through the statistical analysis. The average values and standard deviations are calculated from many sets of independent measurement data. And the half width of the interval corresponding to 95% probability is less than 3dB, thus the maximum limit and minimum limit are defined. Furthermore, a measurement example is performed to show how to find the anormal points which is greater than the maximum limit or less than the minimum limit and ensure the accuracy of the measurement results by adjusting the measurement system.