聚能定向电磁脉冲天线设计+文献综述
本课题以某型低速空投子弹药为基础，以动力学特性为主约束，中心频率10GHz下的超宽带（UWB）电磁脉冲增益为目标函数，优化设计了一种兼有减速稳定和电磁脉冲定向辐射功能的伞形抛物面天线。
为了进行动力学特性研究，首先将外弹道简化为两段主弹道，考虑两种伞形天线结构，结合附加质量理论，准定常流动等理论建立起伞弹运动模型与弹道方程；再根据投放瞬时的初始弹道参数求解弹道方程，得到两种伞形天线的姿态，并以扰动角为评价标准，确定伞型2更优，并优化出伞口径为0.64m。
为了进行辐射特性研究，首先确定角锥喇叭为馈源，建立馈源方向图模型；然后考虑口径振幅降分布、H面和E面分布的影响，建立起馈源辐射效率模型；再独立分析抛物面结构的几何光学特性以近似建立口径场分布，进而得到其远场分布，从而得抛物面方向系数模型，并独立考虑口径分布和漏溢影响，建立起抛物面辐射效率模型，结合方向系数模型得增益模型；最后结合馈源效率和抛物面增益，建立起总增益模型。
为了进行优化，运用了混沌粒子群算法（CPSO），搜索到理想最优增益为36.88dB，并确定出了最优尺寸；然后通过工程离散方法给出了总增益随结构尺寸的变化情况，近似得到最优增益位置，验证了算法结果的精确性。结果表明算法解精度更高，且最优增益要高出0.39dB。根据最优结构，设计了伞弹系统，分析了方向图、相对振幅、频率特性和效能特性，并得到了四个效能等级下临界功率与作用半径的关系。结果表明该天线具有很强的方向性，中频段特性较好，频宽10.8dB，最优增益约41dB。
最后运用Ansoft HFSS软件进行伞形天线仿真，得到了其电特性参数，E面和H面的方向图及相对振幅图，并与理论计算结果进行了对比，验证了理论模型的可信度。仿真得到的增益约34.4dB，效率约40%，均略小于简化的理论计算结果。
毕业论文关键词 电磁脉冲天线 伞形天线 增益 辐射效率 混沌粒子群优化
毕业设计说明书外文摘要
Title Directional electromagnetic pulse antenna design
Abstract
The electromagnetic pulse weapon has been emphasized widely, for its significant damages to communication, detection and control facilities and other electronic systems. And, the requests on defense and anti-terrorism tasks have been increasing recently, so the study on miniature electromagnetic pulse weapon has been a hot issue, and the directional electromagnetic pulse radiation technology with high efficiency has been a key especially.
This study is based on some airdrop submunition with low velocity, the dynamic characteristics are set as main constraints, and the gain of ultra-wideband (UWB) electromagnetic pulse is set as the optimization objective, so that a kind of parabolic parachute antenna with functions of deceleration and stabilization, and directional electromagnetic pulse radiation is optimized and designed.
For the study on dynamic characteristics, firstly, the external ballistic is simplified as two main ballistics, and two kind of antenna parachute structures are considered, so that parachute-bomb dynamic models and ballistic equations are established, combining added mass, quasi-steady flow and other theories; then, the ballistic equations are solved based on initial ballistic parameters on airdrop moment, so that the attitudes of two parachutes are obtained, and the results indicate that the 2nd type is better with disturbance angle as the evaluation standard, and the optimal diameter is obtained, 0.64m.
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