文档介绍：Classified Index: TN822+.3 :
Dissertation for the Master’s Degree in Engineering
RESEARCH ON MINIATURIZATION TECHNOLOGY OF HF ANTENNA
Candidate:
Lv Yanming
Supervisor:
Prof. Qiu Jinghui
Academic Degree Applied for:
Master of Engineering
Speciality:
ic Field and Microwave Technology
Affiliation:
School of Electronics Information Engineering
Date of Defence:
Jul. 2, 2012
Degree-Conferring-Institution:
Harbin Institute of Technology
摘 要
短波(HF)波段的频率范围是 3MHz~30MHz,对应波长 10m~100m。短波无线电系统探测距离远,有较远的中继范围和较强的抗毁性。但是目前在用的短波天线多数尺寸较大,难于运输、安装和维护,因此短波通信设备发展的主要挑战就是天线尺寸小型化问题。小型化的短波天线是电小天线,其带宽和效率受到尺寸的限制。因此在保证短波天线基本性能的前提下研究短波天线的小型化技术是十分必要的,也是本文研究的主要内容。
本文从电小天线的基本理论出发,总结了电小天线的定义,整理了电小天线主要的性能参数,包括:效率、增益、输入阻抗、工作频带宽带、品质因数和增益带宽乘积。明确了设计电小天线时优先考虑的参数,即效率、增益和带宽。总结了分析电小天线的方法,为下一步设计天线给出了理论依据。随后本文具体讨论了加载技术、分形技术和宽带匹配网络技术等常用的天线小型化技术,为进一步设计天线提供了技术资料。
本文提出仿照超宽带天线的结构形式,设计了一种新型双半球线栅结构小型化短波天线。采用 CST Microwave Studio®软件建立模型并仿真分析。仿真结果表明该天线的-10dB 阻抗带宽为 20MHz~30MHz,相对带宽 40%,工作频带内效率高于 90%。天线高 ,横向最大尺寸 。天线高度是工作频率高频端波长的 33%, 低频端波长的 22%,达到了小型化要求。制作了 1:5 缩比模型天线,测量了驻波比、增益等指标,与仿真结果基本一致。
在此设计方案基础上,进一步研究了拓展天线带宽的两种方法,即集总加载和介质加载。用集总元件加载的天线在 3MHz~30MHz 频率范围内驻波比小于 , 增益大于-20dB,满足指标要求,具有实用价值。介质加载的天线受到介电常数和介质层厚度的限制,加载效果不明显。本文设计的天线可以广泛应用在短波通信、超视距雷达等领域。
关键词:短波天线;小型化;电小天线;加载;频带扩展
Abstract
The shortwave (HF) band is from 3MHz to 30MHz,with wavelength from 10m to 100m. The shortwave radio system has the advantages of long detection distance, strong
invulnerability,long unrepeated span and so on. However, the HF antennas usually get
the disadvantage of large size, which makes it uneasy for transportation, erection and maintenance. A major challenge of the development of munication equipment is to miniaturize the antenna size. A miniaturized HF antenna means an electrically small antenna. The bandwidth and efficiency are limited by its size. Therefore it is necessary to research on the miniaturization of HF antenna while maintaining acceptable performance. This is also the focus of t