Research On Power Density Standard From 18GHz To 26.5GHz

Currently, many nations have attached great importance to the research of the power density standard. The existing standards are mostly in the frequency range of 1GHz-40GHz with the power density upper limit of 10 mW/cm2. The only criterion of such a calibration system in China is the 1-18GHz power density standard developed by National Institute of Metrology. However, there are still some gaps between this standard and the world's advanced level. Therefore, to narrow the technological gap between us and developed countries and to push forward the development of scientific research and national economy in China, it's extremely necessary to extend the calibration frequency and power density range of this standard.The purpose of this study is:to build a complete, accurate, traceable microwave power density standard system, with the frequency range of 18-26.5GHz and density range≥5mW/cm2. This paper's main researches are as follows:1,The specific process of building up the standard system based on the Standard Field Method is introduced. And several key issues involved to establish the standard are pointed out.2,One of the key issues, horn antenna gain, is in-depthly analyzed. For near-field gain, this paper calculates it with MoM and then compares the results with NPL measured ones. The comparison shows good agreement between the two. For far-field gain, it is simulated by two different simulation softwares (based on MoM and FITD) separately. By comparing the simulated values, NPL measured values and the theoretical values, it's easy to see that the simulation results consist with the prediction of Kirchhoff formula and the experimental results very well.3,The system control software is developed based on the VB development platform and GPIB interface. In the power input control, by using the relation curve between signal input and net power fed into the antenna abtained through actural test, the efficiency of the test system has been improved.4,The analysis method of measurement uncertainty is studied. This paper establishes a mathematical model and takes the 18GHz power density standard measurement uncertainty for example to analyze the evaluation methods of measurement uncertainty in detail.