双星发射机研制与5.8G系统驻波系数实时监测
Research & Make of Transmitter of Double Star and Real Time Watch and Measure of the VSWR of 5.8G System

中文摘要
射频发射机是无线通信系统的重要组成部分。双星定位系统中发射机的设计、制作、调试和后来的小型化构成了论文工作的第一部分。在这一部分，论文主要介绍了一种用高Q值谐振腔体制作的压控振荡器（VCO）的原理和调试过程。锁相环本振的设计和高本振-射频隔离混频器的选取对系统结构和性能起着关键作用。
论文的另一部分工作是5.8GHz通信系统中发射机功率和天线驻波系数(VSWR)的测量。发射功率和天线驻波系数是发射机的两个重要参数。测量这些参数的目的是检查发射机系统工作状况，并根据需要对其进行调整，在系统工作异常时给出警告或采取必要的措施。
为了减小对待测系统的影响，功率测量一般通过定向耦合器来进行。定向耦合器把发射机输出功率或者天线入射功率按一定比例耦合到耦合输出端，根据那里的检波器的测量结果可以反算出输入功率。同样的方法也可以测出从天线反射回来的功率，于是可以算出天线电压驻波系数。
定向耦合器的特性对测量结果起着关键作用，方向性不够是造成测量误差的主要原因。因此，提高方向性就成了定向耦合器设计的主要任务。论文中给出了多种微带线定向耦合器的理论分析和设计结果。检波器对于功率检测是必不可少的，检波器的特性在一定程度上影响着测量结果，故选一个或者制作一个好的检波器也是非常重要的。
驻波系数测量的结果证明上述方法是可行的，同时测量误差表明定向耦合器的方向性还是不够高。加入校正的话，对于一定范围内的驻波系数可以得到比较准确的结果。

关键词：发射机，驻波系数测量，定向耦合器

Abstract
RF transmitter is an important part of a wireless communication system. The design, make, test and the last miniaturization of the transmitter in the double star position system compose the first part of the thesis. In this part, the theory and debugging process of a voltage-controlled oscillator (VCO) using a syntonic cavity with high value of Q. The design of phase-locked synthesizer and choose of high LO-RF isolation mixer greatly affect the structure and performance of the system.
The other parts of this thesis are measurements of the transmitting power of the transmitter and voltage standing wave ratio (VSWR) of the antenna in the 5.8GHz communication system. The transmitting power and the VSWR of antenna are very important parameters of a transmitter. The purpose of the measurements is checking the working status of the transmitter, adjusting it as demand and sending out the warning message or performing some necessary steps when the system works singularly.
To decrease the affection to the device under test, the power is always measured through directional couplers. The output power of the transmitter or incident power of the antenna is coupled to the coupled port pro rata. We can calculate the original power with the results measured by the detectors there. The reflection power of the antenna can be measured in the same way. So we can calculate the VSWR.
The characteristics of the coupler act an important part in the measurement. The non-ideal directivity is the main causation of the error. So, the chief role for designing the directional coupler is to increase its directivity. The theory analysis and designing results of several kinds of coupling microstrip directional couplers are described in the paper. Detector is the absolutely necessary part when measuring power. The characteristics of detectors affect the measuring results to some extent. So it is very important to choose or make an appropriate detector.
The measuring results of VSWR show that the measure method above is right. And the errors show that the directivity of the directional couplers is not big enough. If adjustment is made, to the VSWR in certain range, we can get a more exact result.
Key words: Transmitter, Measurement of VSWR, Directional coupler
 
目录
中文摘要 I
Abstract II
目录 IV
第1章 引言 1
1.1 无线通信系统发展的历史和现状 1
1.2 射频前端发射机简介 2
1.2.1 发射机指标 2
1.2.2 发射机结构 4
1.3 论文各部分内容简介 5
第2章 双星发射机的研制 7
2.1 双星定位系统 7
2.1.1 双星定位系统的历史和现状 7
2.1.2 双星定位原理 8
2.1.3 双星定位系统的特点和应用 10
2.2 双星发射机 11
2.3 双星系统的本振 12
2.3.1 双星收发系统本振 12
2.3.2 压控振荡器（VCO）的研制 13
2.4 双星系统的小型化 19
2.5 小结 20
第3章 5.8G系统驻波系数监测 21
3.1 5.8GHz无线接入系统 21
3.1.1 5.8G发射机总体结构 21
3.1.2 功率测控系统的结构和作用 22
3.2 功率和驻波系数测量的理论分析 25
3.2.1 电压反射系数和驻波系数 25
3.2.2 功率和驻波系数测量原理分析 26
3.2.3 驻波系数测量系统误差分析 28
3.3 驻波系数测量结果 31
3.3.1 检波器的特性测量 31
3.3.2&nbs

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