小型化宽带功率检测模块设计与实现

发布时间：2018-11-17 10:16

【摘要】：微波功率测量在微波通信、雷达、环境遥感和医学研究等领域有重要的学术和商用价值,现代微波功率测量技术正朝着小型化、模块化和宽频带等方向发展。本文分析了当今国内外微波功率测量技术的发展状况,结合宽带微波大功率相关项目的需求制定了小型化宽带功率检测模块的总体指标和实施方案。主要由微波功率耦合器、开关滤波器组、微波功率检波以及显示与保护电路四部分组成。采用通过式测量法,在ADS09和IE3D中设计了带状线定向耦合器,使功率测量系统可嵌入待测系统中进行实时监测。耦合器使用频段为6GHz~18GHz,耦合度为20±0.7dB,方向性优于16dB,插损小于0.3dB,驻波比小于1.2,尺寸较小。由于工程应用中,微波信号常夹杂着谐波,本系统采用开关滤波器组实现基波与谐波的分开测量,这是本测量系统的创新之处。微波开关选用了高性能的Agilent N1810UL机电同轴开关,频率高达26.5GHz,插损小于0.7dB,单刀双掷。滤波器组由6GHz~10GHz、10GHz~18GHz两通道悬置带状线带通滤波组成,拥有悬置带线高Q值、低损耗的特性。两带通滤波器的插损小于0.5dB,反射大于15dB,带外抑制大于40dB(偏300MHz),性能相近。微波功率检测系统的核心部分是微波功率检波模块,也是本文的设计重点。采用二极管前端宽带匹配,后端低通滤波的电路模型,设计了基于SMS7630-061的肖特基二极管检波器。使用S参数仿真出其反射和插损,谐波平衡仿真得出输入功率-输出电压曲线,加工装配好的检波器在6GHz~18GHz频段内,功率量程为-35dBm至10d Bm。显示与保护电路模块作为后端信号处理部分,需要将检波模块的模拟信号转换为数字信号,然后经算术均值滤波、查表和分段线性插值等算法处理后得出相应的功率值。本系统ADC模块采用24位的ADS1220,采样精度高;核心控制器是ARM系列的STM32F103VCT6,集成功能丰富;输入输出通过USART和LCD触屏实现不同场合下的人机交互。此外,当比较器检测到功率超过一定阈值时,将控制MOSFET开关电路,切断信号或是电源以保护微波系统中的关键部件。最后分析了测量系统中存在的失配误差和温度误差,并提出了相应的误差修正方法。最终完成了小型化宽带功率检测模块的设计。该系统尺寸较小(约为250mm*75mm*55mm),连接形式灵活,成本低,能实时准确地检测6GHz~18GHz宽带微波信号的功率(平均功率),实现基波功率和谐波功率的分开测量;功率量程为-15dBm~30d Bm,测量误差小于等于±0.4dB;具有小型化、数字化、准确性和重复性良好等特性,并具备功率过载报警及对微波电路系统的自动保护功能。
[Abstract]:Microwave power measurement has important academic and commercial value in microwave communication, radar, environmental remote sensing and medical research. Modern microwave power measurement technology is developing towards miniaturization, modularization and broadband. In this paper, the development of microwave power measurement technology at home and abroad is analyzed, and the overall index and implementation scheme of miniaturized wideband power measurement module are established according to the requirements of wideband microwave power related projects. It consists of microwave power coupler, switch filter bank, microwave power detector and display and protection circuit. The strip line directional coupler is designed in ADS09 and IE3D by the method of passing measurement, so that the power measurement system can be embedded in the system to be monitored in real time. The frequency band of the coupler is 6 GHz ~ 18 GHz, the coupling degree is 20 卤0.7 dB, the directivity is better than 16 dB, the insertion loss is less than 0.3 dB, the standing wave ratio is less than 1.2, and the size is smaller. Because the microwave signal is often mixed with harmonics in engineering application, the system uses the switch filter bank to realize the separation of fundamental wave and harmonic, which is the innovation of this measurement system. The microwave switch uses the high performance Agilent N1810UL electromechanical coaxial switch, the frequency is as high as 26.5 GHz, the insertion loss is less than 0.7 dB, the single pole double throw. The filter bank is composed of 6GHz / 10GHz / 10GHz / 10GHz two-channel bandpass filter with high Q value and low loss. The insertion loss of the two bandpass filters is less than 0.5 dB, the reflection is greater than 15 dB, the out-of-band suppression is larger than 40dB (partial 300MHz), and the performance is similar. The core part of microwave power detection system is microwave power detection module, which is also the focus of this paper. A Schottky diode detector based on SMS7630-061 is designed by adopting the circuit model of diode front-end wideband matching and back-end low-pass filtering. S parameters are used to simulate its reflection and insertion loss, and harmonic balance simulation is used to get the input power output voltage curve. The fabricated geophone is in the 6GHz~18GHz band, and the power range is-35dBm to 10 d Bm.. As the back-end signal processing part, the display and protection circuit module needs to convert the analog signal of the detection module into digital signal, and then get the corresponding power value by arithmetic mean filter, look-up table and piecewise linear interpolation algorithm. The ADC module of this system uses 24 bits ADS1220, to sample the precision high; the core controller is the ARM series STM32F103VCT6, integration function is rich; the input and output realizes the man-machine interaction under different situations through USART and LCD touch screen. In addition, when the comparator detects that the power exceeds a certain threshold, the MOSFET switch circuit will be controlled and the signal or power supply will be cut off to protect the key components in the microwave system. Finally, the mismatch error and temperature error in the measurement system are analyzed, and the corresponding error correction method is proposed. Finally, the design of miniaturized wideband power detection module is completed. The system has small size (about 250mm*75mm*55mm), flexible connection form and low cost. It can detect the power (average power) of 6GHz~18GHz wideband microwave signal in real time and accurately, and realize the separate measurement of fundamental power and harmonic power. The measuring error of-15dBm~30d Bm, is less than 卤0.4dB. it has the characteristics of miniaturization, digitalization, accuracy and reproducibility, and has the function of power overload alarm and automatic protection to microwave circuit system.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM933.3

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