Research On Low Frequency Performance Of The Semi-anechoic Chamber

With the continuous development and application of wireless communication technology,electromagnetic compatibility issues of electronic electrical products and systems is particularly important. As an important part of theelectromagnetic compatibility test system-semi-anechoic chamber play an irreplaceable role. At the same time, the performance of semi-anechoic chamber has also attracted more and more attention, especially with the increasing number of electrical and electronic equipment and systems operating in the low frequency range, the low frequency performance of the semi-anechoic chamber plays a key role in accurately assessing its electromagnetic compatibility, therefore, the study of low frequency performance of semi-anechoic chamber has important significance and application prospect. This article focus on the performance index of the semi-anechoic chamber — the field uniformity and the normalized attenuation of the field are studied in the low frequency range.The main contents are as follows:(1) Based on the analysis of the characteristics of ferrite and shielding chamber,the electromagnetic parameters of the ferrite in the 10kHz?30MHz band are obtained by extrapolation fitting method, and the absorbing properties of the ferrite are analyzed theoretically. The second-order dispersion model is used to set the material parameters in the software, and the reflectivity of the ferrite is simulated , According to the theory, simulation and measurement of the ferrite absorption characteristics,verifying the feasibility of data from the side. At the same time, the resonance of the semi-anechoic chamber are analyzed,the simulation results show that the ferrite can suppress the resonance of the shielded chamber, so that the semi - anechoic chamber can simulate the open field well in the low frequency band.(2) In view of the study of field homogeneity, the experimental principle and method are expounded, According to the field uniformity test method, the uniformity model of the semi-anechoic chamber field is established. The field intensity distribution of the semi-anechoic chamber before and after the ferrite is compared and analyzed. The FDTD algorithm is used to simulate the field uniformity of the semi-anechoic chamber, the field uniformity of the measured were compared.(3) For the study of NSA, according to the experimental principle and method,the site reference method is used to simulate the NSA using FDTD algorithm, and the comparison is made.At the same time, the measured results show that the simulation results are in agreement with the measured ones, and the error is within the acceptable range...