【作者】 沈飞；

【导师】 魏彦玉；

【作者基本信息】 电子科技大学 ， 物理电子学， 2012， 博士

【摘要】 毫米波功率模块是基于微波功率模块发展而来的毫米波功率放大器，它兼有小型化毫米波行波管和固态放大器的优点。相比于传统的固态放大器和行波放大器，毫米波功率模块在尺寸、重量及效率等方面都具有较大的优势，因此，在军事及民用等领域具有重要的价值。目前，微波功率模块用的行波管大多是螺旋线行波管，它的宽频带、工作电压低，而且效率高。但是当工作频段上升到V波段甚至更高时，螺旋线行波管的慢波结构尺寸将变得非常小，以至于传统的加工手段已不能满足其在精度上的要求。利用现代微细加工技术制造小尺寸螺旋线是解决这一问题的出路，然而现代微细加工技术主要适用于二维结构的加工。因此，作为一个三维慢波结构，螺旋线的加工过程是非常繁琐和困难的，而且其加工的一致性与可靠性也得不到保证。在这种情况下，寻求一种既能够适用于二维微细加工技术又具备螺旋线慢波结构优点的新型平面慢波结构具有非常重要的现实和科学意义。微带曲折线慢波结构是一种二维平面慢波结构，该类慢波结构具有工作电压低、频带宽、效率高和易于加工等优点。同时由于微带曲折线慢波结构可以与固态电路进行良好的匹配，因此可以将微带曲折线行波管用于毫米波功率模块的末级功率推动器。深入开展微带型慢波结构的研究工作对毫米波功率模块向短毫米波、太赫兹方向的发展具有重要的推动作用。本文从模拟计算和实验两方面对微带型慢波结构进行了深入的研究，主要的工作和创新点如下：1.提出了U形微带曲折线慢波结构。设计了Ka波段U形微带曲折线行波管的慢波结构、衰减器和能量耦合结构，建立了具有集中衰减器的注-波互作用三维模型，分析了注-波互作用过程中电子注和高频场的能量变化情况，得到了各频点处的输出功率。研究结果表明：U形微带曲折线行波管的瞬时3-dB带宽为9GHz，即可以在29GHz到38GHz的频带范围内产生大于100瓦的峰值输出功率。同时，该行波管在34GHz频率点的峰值输出功率可达200瓦，与之相对应的增益和平均电子效率分别为33dB和14.4%。2.为了拓展微带曲折线慢波结构的工作带宽，本文提出了V形微带曲折线慢波结构。通过对相同尺寸的两种微带曲折线慢波结构的高频特性进行对比发现：V形微带曲折线慢波结构的色散特性要明显优于U形结构，V形结构的“冷”工作带宽比U形结构宽30%。建立了有衰减器的V形微带曲折线行波管三维物理模型，对V形微带曲折线行波管的非线性互作用过程进行了模拟分析。研究结果表明：在W波段，V形微带曲折线行波管的瞬时3-dB带宽可达20GHz，在97GHz频率点该行波管的峰值输出功率可达90瓦。3.提出了上下对称的双V形微带曲折线慢波结构。在相同的结构尺寸和互作用电气参数下，本文对两种V形微带曲折线行波管的性能进行了比较。粒子模拟结果显示：双V形微带曲折线行波管的瞬时3-dB带宽为18GHz的带宽，峰值输出功率达到了110瓦；而单V形微带曲折线行波管则有15GHz的瞬时3-dB带宽，峰值输出功率为25瓦。很明显，双V形微带曲折线的行波管的性能要优于单V形微带曲折线行波管。4.对W波段V形微带曲折线行波管进行了热分析。行波管的热分析，为提高行波管的稳定性和可靠性提供了有效的途径，同时对完善行波管的设计，尤其是毫米波新型慢波结构行波管的设计也具有重要的意义。本文利用ANSYS软件对V形微带曲折线行波管慢波结构的散热性能进行了计算和分析，得到了V形微带曲折线行波管慢波结构中各部件的温度分布云图及热流密度矢量图。5.微带曲折线慢波结构传输特性的测量。详细介绍了微带曲折线慢波结构及其输入输出结构的设计、加工和实验测量。实验结果显示：在32GHz到40GHz的频带范围内，U形微带曲折线慢波结构的传输参量S21大于-3dB，反射参量S11低于-10dB；V形微带曲折线慢波结构的传输参量S21在-4dB左右，反射参量S11低于-14dB。更多还原

【Abstract】 Millimeter wave power module is a new concept of millimeter wave amplifierdeveloped from microwave power module that has both the advantages of a miniaturemillimeter-wave traveling wave tube (TWT) and a solid state amplifier. Millimeterwave power module is designed for a wide variety of military and commercialapplications, due to its size, weight and efficiency advantages compared to traditionalsolid-state and traveling wave amplifiers.So far, the helix TW is a main choice for microwave power module because of itsinherently wide bandwidth, low operating voltage and relatively high RF efficiency.While, as the operating frequency increases to V-band or above, the dimensionalparameters of the helix traveling wave tube become rather small. So, the traditionalmachining precision is insufficient for helix. Micro-fabrication technique, as a way tosolve this problem, is more naturally applicable to two-dimensional structures.Therefore, as a three-dimensional structure, the fabrication process of the helix circuitwill be rather complicated and difficult. It is essential for us to quest a new type ofslow-wave structure which retains the advantages of helix TWT but overcomes thefabrication problems.A slow-wave transmission line, of the microstrip type, called microstrip meander-lineslow-wave structure, is now proposed for a low voltage, wide bandwidth and moderatepower millimeter-wave traveling-wave tube. Its fabrication is very convenient byutilizing the two-dimensional micro-fabrication technology, and this type of slow wavestructure can be well-matched with the solid-state circuits. Therefore, it can be used forthe vacuum power booster of MMPM. The development of MMPM will benefit fromthe study of microstrip meander-line slow-wave structure, when its operating frequencyincreases to short millimeter or above. In this thesis, some important and valuableresults which bring forth some new ideas are accomplished and listed as the followings:1. Based on the traditional structure, the U-shaped microstrip meander-line slowwave structure is proposed. The beam-wave interaction model, including the slow-wavestructure, attenuator and the energy coupled structures, has been designed for Ka-band U-shaped microstrip meander-line millimeter-wave TWT. The simulation results showthat the instantaneous3-dB bandwidth of this millimeter-wave power amplifier is about9GHz, ranging from29GHz to38GHz. Its peak output power is about200watts withthe corresponding gain of33dB and averaged electronic efficiency of14.4%at34GHz.2. In order to extend the operating bandwidth of microstrip meander-line slow-wavestructure, a novel V-shaped microstrip meander-line slow wave structure is proposed.The high frequency properties comparison between U-shaped structure and V-shapedstructure has been put forward with all the dimensional parameters set to be equal. Then,the beam-wave interaction of this V-shaped microstrip meander-line millimeter-waveTWT is investigated in detail. The simulation results show that the instantaneous3-dBbandwidth of the V-shaped microstrip meander-line TWT is about20GHz and the peakoutput power is about90watts at97GHz.3. In order to reduce the electron beam density, a symmetric double V-shapedmicrostrip meander-line SWS is proposed. With all the dimensional and electricalparameters ste to be equal, the performance comparison between the double V-shapedmicrostrip meander-line TWT and the single V-shaped microstrip meander-line TWThas been carried out. The simulation results show that the instantaneous3-dB bandwidthof double V-shaped TWT is about18GHz and the peak output power is about110watts.However, the instantaneous3-dB bandwidth of single V-shaped TWT is about15GHzand the peak output power is only25watts. Obviously, the performance of doubleV-shaped TWT is superior to that of single V-shaped TWT.4. The thermal analysis of the V-shaped microstrip meander-line slow wave structureis put forward at W-band. The thermal analysis is an effective way to improve thestability and reliability of the TWT. Moreover, it is essential for us to perfect the designof TWT, especially for the millimeter wave TWT with new type slow-wave structure.The temperature distribution and heat flux vector of the V-shaped microstripmeander-line slow wave structure are obtained by utilizing the ANSYS software.5. The transmission properties of the microstrip meander-line slow wave structuresare measured. In the thesis, the design and fabrication of the microstrip meander-lineslow wave structures including the energy coupled structures are described in detail.According to the experimental results, the transmission parameter S21of U-shapedmicrostrip meander-line is>-3dB, and its reflection parameter is <-10dB in the frequency range of32-40GHz. The transmission parameter S21of V-shaped microstripmeander-line is about-3dB, and its reflection parameter is <-14dB in the frequencyrange of32-40GHz.更多还原