| The cycles of vapor and energy in the atmosphere are important factors that affect theclimate change. Cloud is the intersection of both cycles and precipitation is a veryimportant process in the realization of both cycles. In the cloud detection of the atmosphere,the Terahertz wave, compared with the microwave and the millimeter wave, has thecharacteristic of wide bandwidth range. Under the same condition, the antenna beam ismore narrow and accurate, making the Terahertz wave has a prospect of wide application inthe meteorological detection field. However, a small amount of findings had referred to thefield of Terahertz weather radar in China until now. The objective of this paper is toinvestigate the scattering property of cloud particles and to design a radar system withTerahertz detection.To begin with, the research background, including the overseas and domestic researchprogress and main problems in cloud detecting radar field, is reviewed simply. Next, thescattering characteristics of cloud particles will be investigated using DDA and FDTDalgorithms which provide with the reliable theoretical evidence for radiation transfer andinversion of cloud parameters. Then, the conception of reflectivity factor Z is introduced byradar equation. In addition, the comparison of those Terahertz weather radar parametersfound in research findings overseas is also carried out. Subsequently, the general designscheme is proposed according to the parameters of cloud radar and modules in system arespecifically designed and simulated. Finally, a3dB branch-orientation coupler is designedand tested for the convenience of system test, the result of which shows a goodperformance of this system. |
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