| As one of the electromagnetic compatibility test sites, reverberation chambers have many advantages compared with other common EMC test sites such as open area test sites and semi-anechoic chambers, for example:they can generate higher level of electromagnetic field with lower radio frequency power within the scope of a large volume of space, can produce statistics uniform field strength without rotating the EUT, etc. Therefore, in recent years, it is getting more and more attention and use. But during the working process of a reverberation chamber, we need to do relevant tests at different sampling statuses of the stirrer, which makes the reverberation chamber calibration and test a time-consuming task. So it is necessary to develop a set of automatic calibration and test system. On the other hand, the immunity level (namely the test class) required in radiation susceptibility tests is higher and higher so that the selection of the radio frequency power amplifier is particularly important. It will play an important guiding role in the power amplifier selection to determine the relationship between the indoor field intensity and the input power of reverberation chambers qualitatively.In this paper, firstly, a site of automatic calibration and test software based on the C#programming language for reverberation chambers was developed according to the reverberation chamber calibration and test methods demanded by standard IEC61000-4-21. The software is mainly used to complete the field uniformity calibration, the maximum load calibration, the EUT load calibration and the radiation susceptibility test of a reverberation chamber. At the same time, in order to make the software work better, the functions of the test equipment information managing and the result processing of tests were added. In the program, to complete the measurement of data at different spatial locations, different frequencies and different stirrer sampling points in the calibration and test, a method of three layers of cycle was used. For the preservation of calibration and test results, the serialization technology of C#was adopted to serialize the object contained the data to a local hard disk file, and the deserialization technology was used to read them. The control of instruments was completed through the NI-VISA platform. And the main program called the instrument driver programs by the reflection technology. Then, the field uniformity calibration and the maximum load calibration were performed for the reverberation chamber of Beijing Jiaotong University EMC laboratory with this set of software. The field uniformity was checked and a series of parameters such as the maximum load factor, the antenna calibration factor, the insertion loss and the Q factor were determined. Meanwhile, the EUT load calibration and the radiation susceptibility test were performed with four pieces of absorbing material as the simulated EUT. Therefore, the feasibility of this set of software was verified. As the use of this software, the efficiency of the reverberation chamber is greatly improved.Finally, the relational expression was derived from the definition and the calculation method of the Q in standard IEC61000-4-21respectively and its validity was verified by measured data. Then, the characteristics of this expression were analyzed and the determination methods of its Q parameter were described. Its important guiding role for the selection of radio frequency power amplifiers was verified through an application example. |
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