便携式单端口矢量网络分析仪射频通道电路的设计与实现

发布时间：2018-12-16 20:53

【摘要】：网络分析仪是一种非常重要的射频微波仪器被广泛的应用在射频微波器件和设备的测试测量领域。矢量网络分析仪可以测量元件的幅度、相位和群时延,显示在史密斯图中端口阻抗,并且使用它的时域功能,显示从测试端口到阻抗失配或电路故障处的距离。主要用于被测网络散射参量双向S参数的幅频、相频及群时延等特性信息的测量。网络分析仪由激励源、信道分离器件、用于检测信号的接收机和用于观察结果的显示模块、处理电路组成。随着现在日益增多的无线应用,对矢量网络分析仪的应用环境的要求也越来越复杂。在基站电缆和天线系统、无线电和雷达电缆系统、广播和无线电链路系统的安装维护中,技术工程人员可以使用便携式的单端口矢量网络分析仪简单快捷的测试、评估和发现它们系统故障并解决和排除这些故障从而避免日后高昂的维修费用。并且它可以在恶劣的现场环境迅速对蜂窝网络基础设施、双向无线电通信系统或者任何类型的通信系统进行安装和维护。单端口便携式矢量网络分析仪具有体积小、重量轻、能适应各种测试环境和气候条件下工作的特点。本论文正是针对上述问题,在对单端口矢量网络分析仪设计原理以及工作原理进行分析的基础上,以25MHz至4GHz通信频率范围内单端口矢量网络分析仪的射频通道电路为主要设计对象,利用Altium Designer完成了单端口矢量网络分析仪射频通道电路原理图和PCB的设计和实现。主要内容包括以下几个方面:1.分析单端口矢量网络分析仪的基本结构和工作原理。从而了解网络分析仪的射频通道电路的主要组成电路。确定射频通道部分电路的设计方案和作用。2.分析射频定向耦合器的结构和工作原理,完成25MHz至4GHz频率范围内耦合度15dB,隔离度25dB,直通损耗小于1.5dB,端口电压驻波比下于1.5的射频定向耦合器电路设计并测试射频定向耦合器的各项性能指标。3.分析取样器的机构和工作原理,完成射频工作频率为25MHz至4GHz,本振输入幅度+12dBm、频率为24.8MHz至50MHz,中频接收频率为200kHz的取样器电路设计并测试取样器的转换损耗、转换损耗平坦度和谐波抑制度。4.设计射频定向耦合器和取样器的级联,从而得到需要的射频参考信号和射频反射信号的中频信号。实现整个单端口矢量网络分析仪的射频通道电路的设计并完成其电路印制板的制作。并对射频通道电路进行测试,测量射频端口驻波和端口输出信号电平幅度,最后测试射频通道电路参考通道和反射通道的中频输出电平幅度及幅度平坦度。
[Abstract]:Network analyzer is a very important RF microwave instrument, which is widely used in the field of RF microwave devices and devices. The vector network analyzer can measure the amplitude, phase and group delay of the component, display the port impedance in the Smith diagram, and use its time domain function to show the distance from the test port to the impedance mismatch or circuit fault. It is mainly used to measure the amplitude-frequency, phase frequency and group delay of the bidirectional S parameters of the measured network scattering parameters. The network analyzer consists of excitation source, channel separation device, receiver for detecting signal, display module for observation result and processing circuit. With the increasing number of wireless applications, the application environment of vector network analyzer is becoming more and more complex. In the installation and maintenance of base station cable and antenna systems, radio and radar cable systems, broadcast and radio link systems, technical engineers can use portable single-port vector network analyzers to easily and quickly test, Evaluate and detect system failures and resolve and troubleshoot them to avoid high maintenance costs in the future. And it can quickly install and maintain cellular network infrastructure, bidirectional radio communication systems, or any type of communication system in harsh field environments. Single port portable vector network analyzer has the characteristics of small volume, light weight and can be used in various test environments and climate conditions. Aiming at the above problems, this paper analyzes the design principle and working principle of single port vector network analyzer. Taking the RF channel circuit of the single port vector network analyzer in the frequency range from 25MHz to 4GHz as the main design object, the design and implementation of the radio frequency channel circuit diagram and PCB of the single port vector network analyzer are completed by using Altium Designer. The main contents include the following aspects: 1. The basic structure and working principle of single port vector network analyzer are analyzed. In order to understand the network analyzer radio-frequency channel circuit of the main components of the circuit. Determine the RF channel part of the circuit design and role. 2. The structure and working principle of RF directional coupler are analyzed. The coupling degree from 25MHz to 4GHz is 15 dB, the isolation is 25 dB, and the pass-through loss is less than 1.5 dB. The RF directional coupler circuit with port voltage standing wave ratio of 1.5 is designed and tested. The mechanism and working principle of the sampler are analyzed. The RF operating frequency is 25MHz to 4GHz, the input amplitude of the local oscillator is 12dBm, the frequency is 24.8MHz to 50MHz, and the intermediate frequency receiving frequency is 200kHz. The circuit design of the sampler is designed and the conversion loss of the sampler is tested. Conversion loss flatness and harmonic suppression. 4. The cascade of RF directional coupler and sampler is designed to obtain the if signal of RF reference signal and RF reflection signal. The RF channel circuit of the single port vector network analyzer is designed and the PCB is made. The RF channel circuit is tested to measure the RF port standing wave and the port output signal level amplitude. Finally, the intermediate frequency output level amplitude and the amplitude flatness of the RF channel reference channel and the reflection channel are tested.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM935

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