Correction Of Site Effects On Antenna Factor Measurement

Antenna Factor of EMC antenna is a fundamental parameter in Electromagnetic Compatibility Measurement. All antennas that used to test must be calibrated every year. Thus, the research of Antenna Factor Correction is of great theoretical and practical value.OATS and Semi-Anechoic Chamber is the site where we measure Antenna Factor by international standards. When we measure Antenna Factor in OATS or Semi-Anechoic Chamber, the result will include reflection interference signal because of site factors or surrounding obstacles factors. Thus, the result of measurement may be inaccurate. Author focuses on the influence of site factors in Antenna Factor measurement, and complete some work to eliminate interference of reflection signals and correct the antenna factor.First, author studies the influence on Antenna Factor Measurement of insufficient width of OATS. On the one hand, author analyzes the range of Fresnel Zone on OATS and the effects of termination of site edge, on the other hand, author uses EMC software based on MoM to create the model of biconical dipole antenna and simulate ideal OATS, 10m range OATS by standards and current OATS of insufficient width. At last, author get the conclusion about the effect of insufficient width of site on measurement of different frequency and polarization.Then, author uses time-domain method to analyze the reflection situation in OATS and Semi-Anechoic Chamber, and finds the source of different interference signals in OATS and Semi-Anechoic Chamber. Thus, the foundation for eliminating the interference is built.At last, author studies time-domain gate method to eliminate the interference caused by site factors. In OATS and Semi-Anechoic Chamber, author carries out Antenna Factor comparison measurement with and without time-domain gate in different site setup. The result shows that the reflection interference caused by site factors is effectively eliminated by measurement with time-domain gate. Time-domain gate can obviously correct the measurement result of antenna factor, especially in vertical polarization. Author achieves time-domain gate in Matlab. It builds the foundation for automatic measurement of antenna factor with time domain gate. In addition, author analyzes and points out the antenna type which can be calibrated bytime-domain gate.