非大气窗口毫米波传播特性及近程探测技术研究

发布时间：2018-03-26 04:05

本文选题：非大气窗口　切入点：传输特性　出处：《南京理工大学》2017年硕士论文

【摘要】：在复杂的战场背景环境中,现有毫米波引信系统存在抗干扰能力不足的问题,单一模式和常规频段的探测器已经不能满足军事作战任务。为提高探测性能,必须开拓新的频段和多模式复合的毫米波系统。非大气窗口频段毫米波的大气衰减十分严重,难以适应远距离通信、远距离雷达探测等系统的要求,而毫米波引信的作用距离仅为几米到几百米,探测系统性能受传播衰减的影响较小,此外,非大气窗口毫米波系统对于敌方的侦查和干扰具有十分优越的对抗能力。因此将非大气窗口作为毫米波引信工作频段具有十分广阔的应用前景。本文重点研究非大气窗口频段毫米波的传播特性。根据ITU-R给出的传播衰减模型,对毫米波在晴朗天气条件下的大气吸收、散射和折射效应进行了计算,结果表明大气吸收对毫米波传播过程的衰减起主要作用,且毫米波在60GHz、118.8GHz和183GHz处出现吸收峰。同时分析了降雨和雾霾天气对毫米波传播过程的影响,在两种天气条件下建立了衰减模型并进行了仿真计算,由计算结果可以看出在降雨条件下毫米波的传播衰减剧烈,而在雾霾中的毫米波衰减很小,表明毫米波具有较强的穿透雾霾的能力,而穿透雨的能力较差。基于传播特性分析,理论计算传播衰减对非大气窗口探测系统作用距离的影响。进一步探究工作在60GHz和118.8GHz非大气窗口频段毫米波系统的反侦察特性和抗有源干扰特性。用35GHz大气窗口频段毫米波探测系统的工作性能作仿真对比分析。分析结果在理论上验证了非大气窗口频段应用于近程毫米波引信的可行性。在可行性验证的基础上,本文对60GHz非大气窗口频段FMCW主动探测系统进行了方案论证和信号处理部分的设计。首先说明了FMCW主动测距的原理。然后在时域上和频域上对差频信号进行了分析,并讨论了系统参数选择的原则。其次基于FPGA对60GHz毫米波主动探测系统的信号处理部分进行了软件和硬件设计。最后对以上的系统设计和实现并进行了实验验证,实验结果表明60GHz非大气窗口毫米波系统的测距范围达到120m以上,且测距误差小于5%,满足系统测距要求。非大气窗口频段的传输特性理论分析、建模仿真以及主动探测系统设计和实验验证为该频段应用于近程探测和毫米波引信提供了理论和数据支撑。
[Abstract]:In the complex battlefield background environment, the existing millimeter-wave fuze system has the problem of insufficient anti-jamming capability, the single mode and conventional frequency band detectors can no longer meet the military combat tasks. It is necessary to develop a new millimeter wave system with multiple modes and frequency bands. The atmospheric attenuation of the millimeter wave in the non-atmospheric window band is very serious, and it is difficult to meet the requirements of long-distance communication, long-range radar detection and other systems. The millimeter-wave fuze has a range of only a few to several hundred meters, and the performance of the detection system is less affected by the propagation attenuation. The non-atmospheric window millimeter-wave system has a very superior countermeasure ability to the enemy's detection and interference. Therefore, using the non-atmospheric window as the working frequency band of the millimeter wave fuze has a very broad application prospect. The emphasis of this paper is on the non-atmospheric window as the working frequency band of the millimeter-wave fuze. Propagation characteristics of millimeter waves in the frequency band of atmospheric windows. According to the propagation attenuation model given by ITU-R, The atmospheric absorption, scattering and refraction effects of millimeter waves in sunny weather are calculated. The results show that atmospheric absorption plays a major role in the attenuation of millimeter wave propagation. The absorption peaks of millimeter wave are observed at 118.8 GHz and 183GHz. The effects of rainfall and haze weather on the propagation of millimeter wave are analyzed, and the attenuation model is established and simulated under two weather conditions. From the calculation results, we can see that the millimeter-wave propagation attenuates sharply under the rainfall condition, but the millimeter-wave attenuation in haze is very small, which indicates that the millimeter-wave has a strong ability to penetrate haze, but the ability to penetrate the rain is poor. Based on the analysis of propagation characteristics, The influence of propagation attenuation on the operating distance of non-atmospheric window detection system is calculated theoretically. The anti-reconnaissance and anti-active interference characteristics of millimeter-wave system working in the frequency band of 60GHz and 118.8GHz non-atmospheric window are further explored. The 35GHz atmospheric window is used to study the characteristics of anti-detection and anti-active interference. The performance of millimeter wave detection system in frequency band is compared and analyzed by simulation. The results show that the application of non-atmospheric window frequency band to short-range millimeter wave fuze is feasible. In this paper, the scheme of FMCW active detection system in non-atmospheric window band of 60GHz is demonstrated and the signal processing part is designed. Firstly, the principle of FMCW active ranging is explained. Then, the differential frequency signal is analyzed in time domain and frequency domain. The principle of system parameter selection is discussed. Secondly, the signal processing part of 60GHz millimeter wave active detection system based on FPGA is designed in software and hardware. Finally, the above system is designed and implemented and verified by experiment. The experimental results show that the ranging range of the 60GHz non-atmospheric window millimeter-wave system is more than 120m, and the ranging error is less than 5, which meets the requirements of the system ranging. Modeling simulation and active detection system design and experimental verification provide theoretical and data support for the application of this frequency band in short-range detection and millimeter-wave fuze.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN015

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