| With the developing of electronic devices, electromagnetic environment isbecoming increasing complicated, which makes electromagnetic compatibility (EMC)of electronic devices a more critical problem. How to increase the test precision ofreverberation chamber (RC), to save the test time and to expand domain has spurred alot of interest in recent years. In this paper, the uniformity of electromagnetic field inRC and practical problems of application were investigated and the theoretical modelsfor analysis were extracted. The finite-difference time-domain (FDTD) method wasused to simulate the situations. The contributions done in this paper are as follows:1. Empty cavity calibration of reverberation chamber was studied, and did this tothe RC size of7.6m×5.2m×3.3m from80MHz to18GHz. Sample12was chosen, thatis to say stirrer rotated from0°to360°with30°. It conclude that the field uniformity ofthe empty cavity demand the standard IEC61000-4-21, which propose3dB, from lowestusable frequency (LUF)117.7MHz.2. The generation of random plane electromagnetic wave of superpositionincidence plane waves was analyzed. The cumulative distribution function (CDF) ofincident point (θ, φ) was chosen as the target function and the distribution uniformity ofthe incident wave was chosen as the optimize purpose, the coefficient const in thedenominator of restricted=/(c onst×sinθ)was optimized from1to2. Comparedwith literature results, more uniform random incident plane electromagnetic wave wasobtained.3. Based on the above condition, the effect of different number and frequency ofrandom incident plane electromagnetic on the field uniformity in reverberation chamberwas investigated. And the relation between the number N, repeated times M (whichdenote the sample in testing) of incidence wave and field uniformity was optimized.Compared with literature, on the same field uniformity, N and M decreased rapidly,which minimized the calculation quantity in simulating mostly and advanced thecomputation precision simultaneous. It makes the process from theory to practicalityintensively.4. The effect of different type of diffuser on the field uniformity in reverberationchamber was studied. And especially for the size design of maximum length diffuser(MLD), which was not involved in the previous literature. A new position, located inthe eight corner of RC, of the diffuser in the RC was proposed, which improved thefield uniformity availably. 5. The method of reverberation chamber used to measure small antenna efficiencywas studied. And several practical antennas were tested. It was shown this method issimple and test precise is high. Base on efficiency measurement, an owned broadbanddual-polarized dipole antenna was measured, and the radiation efficiency was higherthan similar antenna. For the power supply, it is important for the electronic systemwhich must pay close attention to the antenna radiation efficiency. It is also a newinnovation that reverberation chamber used to design antenna with high radiationefficiency.6. The method of human body rewarming with accidental hypothermia based onelectromagnetic field of reverberation chamber was researched. It is initiated at homeand oversea. The dispersed form of the bio-heat equation (BHE) was educed, andFourier series was utilized to extract the stabilization condition in particular. A lowtemperature human body with24℃was taken for an example, using10superpositionincident plane electromagnetic waves with f=120MHz and f=915MHz irradiatedtime-sharing and simultaneous. It has been shown that single frequency irradiationtime-sharing can be used to increase temperature rapidly and mixed frequencyirradiation simultaneous can be adopted to obtain uniform temperature elevation. Thisrevelation began using a single low frequency irradiation and then mixed frequencysimultaneous exposure to obtain a fast and uniform rewarming. |
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