【作者】 余爱民；

【导师】 赖声礼；

【作者基本信息】 华南理工大学 ， 电路与系统， 2005， 博士

【摘要】 宽带无线接入技术是21世纪宽带通信技术的主要发展方向之一,是解决“最后一公里”接入问题、第三代个人移动通信用户“带宽瓶颈”问题的关键技术。同时,宽带无线接入技术还是快速解决城市老区的网络综合布线问题和边远农村的信息化建设问题的最佳方案。随着宽带无线接入技术的广泛应用,通信系统之间以及通信基站内部的电磁干扰(EMI)现象越来越严重。其中,宽带无线接入基站的电磁兼容(EMC)问题以及3G通信系统中的系统间的频率干扰问题尤为突出,本文针对这些问题进行了下列研究:第一,综合讨论了宽带无线接入系统的电磁兼容问题,分析了各种宽带无线接入系统的结构和组成特点,总结了宽带无线接入系统的三大EMC特点:1.雷电电磁脉冲(LEMP)对基站的干扰;2.信息设备的宽频带辐射干扰;3.3G通信系统中的系统间频率干扰。第二,对雷电电磁脉冲进行了研究,详细分析了雷电电磁脉冲的产生机理以及雷电电磁脉冲的频谱特性,讨论了雷电电磁脉冲对宽带无线接入基站的袭击形式。对避雷针(接闪器)的保护范围进行了理论分析和计算机仿真,提出了通过采用“球形五针避雷器”,提高基站对侧击雷和感应雷的防范能力的观点。根据法拉第屏蔽笼的屏蔽原理,对基站建筑物的屏蔽接地、防雷地网提出了采用“混合接地体辅助地网”对基站建筑物的“基础接地”进行改进,提高了基站接闪器“引雷”放电时的快速泻电能力。“球形五针避雷器”和“混合接地体辅助地网”是本文的创新点之一。第三,通过引入“广义的高斯定理”,建立了计算地球表面电场的数学模型,对雷电期间地面电场的变化进行了分析计算。根据参阅的大量参考文献,分析了地面电场、空间大气电场在雷电期间的变化情况,提出了“地面临界电场”的概念。根据地面临界电场的概念,在雷电期间进行了长期的地面电场变化监测试验,获取了大量的实测试验数据。通过对实测数据的分析,提出了根据地面临界电场的下限值对首次雷电闪击进行预测的观点,研制了利用地面电场预测雷电闪击的“无线局域网基站智能型防雷电源”,并在课题组的研究试验基地——清新县人民政府公众信息网(具有多个远程无线接入的WLAN,以下简称“清新网”)中进行了实际应用试验,实验获得成功,取得了良好的效果。该防雷电源在2004年7月14日获得了国家实用新型专利的授权(专利号: ZL 03 2 26526.3;专利证书号:626604);利用地面电场预测雷电首次闪更多还原

【Abstract】 Broadband wireless access technology is one of the main developmentes for broadband communication in 21 century. It is the pivotal technology to solve the problem of“Last one kilometer”access and“Bandwidth bottleneck”for 3G mobile users. At the same time, broadband wireless access technology is the optimal scheme that it fleetly solves problems of integrated collocation line for the ancient city zone and informatization of outlying country.With wide application of broadband wireless access technology, the EMI phenomenon is more and more serious among communication systems and inner communication base station. The EMC problem of broadband wireless access base station and intersystem frequency interference of 3G communication systems are very important. For these problems, the researches are as follows:Firstly, the EMC problem of broadband wireless access system was discussed, and the structure and consisting characteristic for different broadband wireless access systems were analyzed. Three EMC characteristics are summarized as follows:1. The interference of LEMP on base station;2. The interference of wide frequency Radiate on information equipment;3. The intersystem Frequency interference among 3G communication systemsSecondly, LEMP was researched. Mechanism and Spectral characteristic of LEMP were analyzed in detail. The attacking form of LEMP to base station was discussed. The protective area of lightning rod was analyzed and simulated with computer. A standpoint using“global five lightning rod”to increase base station capacity of resisting flank attack lightning is proposed..According to principle of Faraday Screen Cage, a standpoint using“accessorial earth net by mixed grounding”to increase base station capacity for discharging quickly as lightning rod lead lightning is presented.Thirdly, a mathematic model for calculating ground electric field was established, and the change of ground electric field during thunder activity was analyzed. According to reference, the concept for critical of ground electric field was brought by analyzing ground electric field and atmosphere electric field.According the concept for critical of ground electric field, a mass of experimental data had been obtained by surveying the changing curves of ground electric field during thunderstorm on the spot. The threshold of ground electric field that triggers the first lightning strike was brought, and“smart base station power supply against LEMP”was developed. The“power supply”was practicality tested in QingXin public information wireless network, and the test had gained success. The“power supply”had acheived patent.(Patent No. ZL 03 2 26526.3,更多还原