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类型 应用研究 预答辩日期 2017-11-21
开始(开题)日期 2014-12-14 论文结束日期 2017-09-16
地点 李文正楼六楼大会议室 论文选题来源 学校自选项目    论文字数 9.6 (万字)
题目 微波毫米波高性能接收前端关键技术研究与应用
主题词 微波毫米波接收前端,陷波结构,群时延波动,负群时延,辐射计。
摘要 微波毫米波接收前端是军/民通信应用系统、高速无线数据传输系统及毫米波探测成像系统中的核心单元,其杂散干扰抑制能力、通带幅频响应平坦度、通带群时延波动及噪声系数是衡量接收机性能的关键技术指标。随着微波毫米波系统应用往更高频率、更宽带宽方向发展,对微波毫米波接收前端提出了更高的要求。因此,研究宽带微波毫米波系统中存在的理论问题及关键技术对于宽带微波毫米波系统应用技术的发展具有重要意义。本文以实现微波毫米波高性能宽带接收前端为目标,对高选择性带阻滤波技术、宽带幅度均衡技术、群时延波动分析与优化、级间阻抗失配对系统幅频响应及噪声系数的影响、高宽带高增益系统中噪声系数精确测量等接收前端中的的理论问题与关键技术进行深入的分析和研究,并应用于Ka波段低幅相失真宽带接收前端、Ku波段低噪声接收变频模块(LNB)及W波段辐射计的研制中,完成了相关实验研究工作。本文的研究进展包括以下内容: 1、提出了一种微带反向并联双耦合陷波结构,这种结构具有阻带双谐振特性,能够有效展宽阻带带宽。仿真分析和实验研究表明该结构相比传统平行耦合陷波结构具有更高的频率选择性和更宽的阻带带宽。基于所提出的反向并联双耦合陷波结构,研制了一款L波段结构紧凑的高选择性带阻滤波器。为解决宽带系统中普通带阻滤波器强反射信号导致的邻近元件性能恶化的问题,研制了一种基于电阻加载平行耦合结构的吸收型带阻滤波器,这种滤波器能够有效的吸收阻带信号;通过对电路方案的改进,使加载电阻的选择具有更大的灵活性;仿真和实验结果表明,研制的吸收型带阻滤波器阻带内传输参数、输入端反射系数均小于-20dB,实现了阻带信号有效吸收。 2、提出了一种基于低阶带通滤波器结合带外陷波结构的低群时延波动带通滤波器的设计方法,并对宽带系统通带内群时延波动特性进行了分析与研究。C波段微带带通滤波器仿真分析和实验研究表明,采用该方法可以同时保证带外高抑制度和带内良好的群时延平坦度特性。将这种设计方法应用于高相位正交性I-Q混频电路中的滤波器设计,测试结果表明,这种方法能显著降低I-Q两路输出电路中滤波器器件参数误差对群时延值的影响,提高了电路的I-Q两路输出信号的相位正交性。 3、为了改善负群时延电路的工程实用性,提出了一种新型的传输型低损耗负群时延电路,并对电路进行了理论和实验分析。电路的负群时延特性是通过在平行耦合谐振单元靠近短路端加载电阻实现的,通过加载不同阻值的电阻可以配置不同的负群时延值,采用径向开路扇形结构实现了电路的紧凑性设计。实测结果表明,该电路可配置获得-2ns~-12ns的负群时延值,其最大信号衰减在6~10dB范围内。相比国外报道的负群时延电路,本文提出的负群时延电路在结构紧凑性、信号衰减、端口驻波及负群时延可配置性等方面均具有明显优势,为负群时延电路在工程中的应用提供了一种实际可行的电路实现方式。 4、建立了微波毫米波宽带系统级间阻抗失配与通带幅频响应的关系的理论分析模型,并针对如何有效改善系统通带幅频响应平坦度进行了深入研究,提出了能够有效改善宽带接收前端系统通带内增益平坦度的宽带幅度均衡方案,并设计了基于并联微带谐振单元的Ka波段幅度均衡器和基于集总参数器件设计的L波段宽带幅度均衡器。结合宽带幅度均衡技术及低群时延波动滤波器设计方法对Ka频段宽带接收前端的系统方案进行优化,实验研究表明,研制的Ka频段宽带接收前端在最大增益达60dB条件下,通带内幅频响应平坦优于±0.45dB,带内群时延波动低于1.8ns,实现了宽频段内低幅相失真。 5、在对射频级间阻抗失配与系统噪声系数之间的关系进行深入研究的基础上,提出了系统噪声系数最优的系统增益配置方法,该方法基于当前器件性能水平对系统逐层分解配置,简化了高增益系统设计中噪声系数、增益的配置和优化的过程。对宽带高增益接收系统的噪声系数测量方法进行了研究,建立了分析增益压缩引起的噪声系数测量误差的理论模型,并提出了噪声系数测量中判断宽带高增益系统是否存在增益压缩的判据。基于上述方法,提出了双频段Ku波段低噪声变频模块(LNB)的设计方案,并研制了关键电路,包括宽带低噪声放大器、输出频点可切换的本振源、高性能Bias-Tee电路及宽带均衡电路等。此外,在满足系统带外抑制要求的条件下,通过适当展宽带通滤波器带宽有效降低了系统通内群时延波动值。实验研究表明,所研制的Ku波段LNB模块噪声系数典型值为0.90dB,通带增益平坦度优于±1.5dB,总体性能指标达到了国外同类商用产品的相当水平。 6、建立了宽带毫米波辐射计的亮温分辨率有效带宽随系统增益不平坦度变化的评估模型,定量分析了通带增益不平坦度对系统有效带宽的影响。对采用超外差体制的W波段单通道和六通道辐射计的系统方案进行了分析设计。通过中频宽带幅度均衡技术和数控增益调节及积分时间调节电路,解决了毫米波宽带系统频域内幅度不平衡和多通道之间增益及温度灵敏度不一致性等关键技术问题。根据低噪放和下变频器的宽带频响特性,研制了宽带均衡中频电路,实现了在11GHz射频带宽内变频增益±1.5dB的优良的幅频特性。构建了W波段辐射计试验样机,对温度灵敏度和长期工作稳定度进行了实验研究,结果表明,研制的辐射计具有优于0.55K的温度灵敏度,长期工作性能稳定可靠性高。
英文题目 Research and Application of Key Technology for Microwave Millimeter wave High Performance Receiving Front-end
英文主题词 Microwave millimeter wave receiving front-end,notch structure,group delay fluctuation,negative group delay,radiometer.
英文摘要 Microwave/millimeter wave receiving front-end is one of the core units in the systems like military/civilian communication system, high speed wireless data transmission system and millimeter wave detecting imaging systems. The performance of a broadband RF receiving system is largely determined by the degree of spurious suppression, the noise figure, the flatness of amplitude response as well as group delay fluctuation in the pass-band. It is of great practical significance to study the theoretical issues and key technologies in the broadband microwave/millimeter wave system for the development of broadband microwave/millimeter wave system. With the goal of achieving the high-performance microwave/millimeter wave broadband receiving front-ends, a series of key technologies and theoretical issues associated with receiving front-end have been studied. Design techniques of high selectivity band-stop filter and broadband amplitude equalizing circuit are proposed. Group delay fluctuation in broad band is analyzed and optimized. The influence of inter-stage impedance mismatching on the amplitude response and noise figure performance are formulated by network theory. Accurate measurement method of noise figure in broadband system with high power gain is studied. The established theoretical model and design techniques are applied in the development of Ka-band broadband receiver with low amplitude and low phase distortion, Ku band LNB module and W-band radiometer. The main achievements of this dissertation are as follows: 1、An antisymmetrical parallel double coupling notch structure is proposed for microstrip band-stop filter. This notch has a double-resonant characteristic in the stop-band, which extends the stopband bandwidth effectively. Compared with the traditional parallel coupled notch structures, the proposed notch shows a higher selectivity and a wider stop band. Based on this new notch structure, an L-band compact band-stop filter with high selectivity is developed. In order to cope with the strong reflected signal from the conventional reflective band-stop filter, which will degrade the performance of adjacent circuit components, an absorptive band-stop filter(ABSF) using parallel coupling structure with loaded lunmped resistor is developed. By adjusting the loading position of the lunped resistor, the flexibility is enhanced for choicing the value of loaded-resistor in the ABSF. Simulated and experimental results show that the transmission parameter and the input port reflection coefficient are less than -20dB in stopband, which indicates that the signal in stopband is absorbed effectively. 2、A novel design method, which is based on a low-order band-pass filter combined with notch structures, for BPFs with low group delay fluctuation is proposed. The effectiveness of improving the fluctuation of group delay in the pass-band of a broadband system has been simulated by Ansoft’s HFSS. Experimental study on a prototype of bandpass filter at C-band demonstrates that the group delay fluctuation has been reduced effectively , while keeping a high out of band signal suppression. This method is applied in the design of low pass filters which are used in the high phase orthogonality I-Q mixer. The measurement results illumstrate that the error of phase orthogonal between I and Q channels is reduced significantly, which is introduced by the value errors of the components used in the filters. 3、To improve the engineering practicality of the negative group delay circuit (NGDC), a novel circuit scheme is presented for the design of transmission-type NGDC with low signal attenuation. The theoretical and experimental analysis of the circuit is carried out. By loading a lumped resistor at a specific point on the parallel coupling microstrip (MS) resonator, the negative group delay characteristics can be obtained. The negative group delay value of the NGDC can be reconfigured by changing the value of loaded-resistor. An open radial patch is employed to further reduce the circuit size. A measured maximum NGD of -2ns to -12ns and a corresponding signal attenuation of 6dB to 10 dB can be obtained by loading the resistor with different value. Compared to the previously reported circuits, the proposed NGD circuit in this work has advantages in regard to circuit size, signal attenuation, reflection coefficients as well as flexible configuration of NGD, which offers a practical way to realize the negative delay circuit in engineering application. 4、The relationship between impedance mismatch in cascaded devices and amplitude- frequency response in microwave/millimeter wave broadband system is studied theoretically and experimentally. Several effective ways of optimizing the gain flatness in the passband are summarized. Theoretical analysis is carried out to the principle of amplitude equalizer, and a broadband amplitude equalization scheme which can effectively improve the gain flatness in the pass-band of the broadband receiving front-end is presented. A Ka-band amplitude equalizer based on parallel microstrip resonators and an L-band wideband amplitude equalizer based on lumped parameter devices are designed. The scheme of Ka-band broadband receiver front-end is optimized by the broadband amplitude equalization technique and the low group delay fluctuation filter design method. The experimental results demonstrate that the Ka-band broadband receiver front-end has a pass-band gain flatness less than ±0.45dB at a maximum gain of 60dB, and a group delay fluctuation less than 1.8ns. 5、The relationship between impedance mismatch in cascaded devices and noise figure in the RF system is analyzed theoretically. A system gain configuration method based on the optimal system noise figure is presented. The method decomposes the system layer by layer based on the current commercial device performance, which simplifies the process of configuration and optimization of noise figure and gain of the cascaded device. The noise figure measurement method of broadband receiver system with high gain is studied. A theoretical model is established for analyzing the measurement error of noise figure caused by gain compression. A criterion which is used to judge if there is gain compression in the noise figure measurement is proposed. Based on the above methods, the design scheme of a dual band Ku-band LNB is worked out. The key circuit parts of the LNB module are designed and fabricated, including the Ku-band broadband LNA, the frequency synthesizer with switchable output frequency, the high performance Bias-Tee and the broadband amplitude equalizer. Under the condition of satisfying the requirement of out-of-band suppression, the group delay fluctuation of the LNB module is reduced by extending the bandwidth of the band-pass filter properly. The experimental results show that the noise figure of LNB module is around 0.90dB, the pass-band gain flatness is better than ± 1.5dB with an overall down-converting gain of 64dB. The performance of the developed LNB module is comparable with that of oversea’s commercial product. 6、An evaluation model is established for estimating the effect of gain fluctuation on the effective bandwidth which determines the brightness temperature resolution of a broadband millimeter wave radiometer. Design sechemes for W band single-channel and six-channel radiometers are worked out by using heterodyne structure. By the IF broadband amplitude equalization technique, the problem of gain unbalance in the broadband millimeter system is compensated. By a circuit with digital justable gain and with justable integration time, the gain and temperature unbalance between channals can be reduced obviously. An IF circuit with broadband equalizer is designed and fabricated according to the broadband gain characteristic of the LNA and downconverter. By cascading these circuits, a gain flatness less than ±1.5dB in a RF bandwidth of 11GHz has been realized for a complete channel of the radiometer. The prototypes of W-band radiometers are constructed, and the temperature sensitivity and long-term stability of the radiometers are studied experimentally. The experimental results demonstrate that the developed radiometers have a temperature sensitivity better than 0.55K, and the long term performance is stable and reliable.
学术讨论
主办单位时间地点报告人报告主题
东南大学毫米波国家重点实验室 2013.06.26 无线谷A3楼3412会议室 陈志宁 120/270GHz毫米波基板集成天线
东南大学毫米波国家重点实验室 2015.07.06 无线谷A3楼3412会议室 Yi Wang Micro-machined mm-wave/THz devices and Multi-role microwave components
东南大学毫米波国家重点实验室 2015.10.16 无线谷A3楼3412会议室 Yihong Qi OTA Testing Methods and Best Practices
东南大学毫米波国家重点实验室 2016.06.21 无线谷A3楼3412会议室 Koichi Ito Microwave Antennas for Medical Applications
毫米波国家重点实验室 2014.04.05 李文正楼北614会议室 刘刚 Ka频段变频器设计报告
毫米波国家重点实验室 2015.10.15 李文正楼北614会议室 刘刚 5.8GHz-ETC前端方案报告
毫米波国家重点实验室 2016.06.12 李文正楼北614会议室 刘刚 宽带系统幅相特性研究报告
毫米波国家重点实验室 2017.03.21 李文正楼北614会议室 刘刚 Novel negative group delay circuit
     
学术会议
会议名称时间地点本人报告本人报告题目
2015 Asia-Pacific Microwave conference( APMC 2015) 2015.12.06~12.09 中国,南京 A Wideband Ka-band Receiver with High Gain Flatness and Slight Group Delay Fluctuation
The 38th Progress In Electromagnetics Research Symposium (PIERS 2017) 2017.05.22~05.25 俄罗斯,圣彼得堡 A Narrowband Absorptive Band- stop Filter Based on a Resistor- loaded Compact Resonator
     
代表作
论文名称
Compact transmission-type negative group delay circuit with low attenuation
A wideband Ka-band receiver with high gain flatness and slight group delay fluctuation
 
答辩委员会组成信息
姓名职称导师类别工作单位是否主席备注
陈彬 正高 教授 博导 解放军理工大学 委员会主席
吴文 正高 教授 博导 南京理工大学 委员
潘明海 正高 教授 博导 南京航空航天大学 委员
薄亚明 正高 教授 博导 南京邮电大学 委员
朱晓维 正高 教授 博导 东南大学 委员
      
答辩秘书信息
姓名职称工作单位备注
王文博 其他 讲师 东南大学