【作者】 李国林；

【导师】 舒挺； 袁成卫；

【作者基本信息】 国防科学技术大学 ， 电子科学与技术， 2010， 博士

【摘要】 随着高功率微波技术的发展与成熟,能够提升高功率微波输出能力的方法越来越受到人们的重视。研究的主要方向有提高微波的输出功率、增加微波的脉冲宽度、提高束波转换效率以及增加频谱覆盖范围等。然而受到物理和技术等方面的限制,利用单个微波源提高微波输出能力的方法目前已遇到较大困难。一种较为有效地解决此问题的方法就是利用高功率微波多路耦合输出技术。本文主要致力于高功率微波的多路耦合输出的研究,介绍了高功率微波多路耦合输出的理论和实验研究结果。总体看来,高功率微波多路耦合输出的研究为高功率微波技术的发展开辟了令人鼓舞的前景,具有重要的理论和实践意义。本文的主要研究结果和创新点有:1.对基于空间滤波原理的线极化波双工器的场增强和空间谐波选择性进行了研究,实现了两路GW级高功率微波的耦合输出。文中利用基于平面波展开的模式匹配法对矩形栅组成的线极化波双工器进行分析,得到了矩形栅双工器的性能对结构参数、入射波频率、入射角度以及其它因素的依赖关系。对矩形栅双工器进行了低功率和高功率实验研究。初步的实验研究表明,矩形栅双工器对S/X波段高功率微波的耦合输出表现出较好的双工性能,但是,受矩形栅表面场增强等因素的影响,当微波幅值和脉宽增加到2.0GW、30ns时微波脉宽出现了缩短,并在双工器沿面发现了表面闪络现象。为了设计更高功率容量的线极化波双工器,本文提出了利用圆柱栅双工器进行长脉冲高功率微波的耦合输出。利用理论分析方法得到了圆柱栅双工器散射的空间谐波选择的相关原则。所设计的圆柱栅双工器在进一步的实验研究中,表现出相对较好的性能。它对所需频段微波的功率反射和透射效率分别达到了97%和97.5%。在1.8GW、100ns高功率微波的照射实验中,没有发现微波击穿现象。为探讨S/X波段两路高功率微波同步输出的可行性,进一步研究了圆柱栅双工器在介质环境中的高功率性能。研究结果表明,置于1atm气压SF6气体中的圆柱栅双工器可满足S/X波段5.5GW高功率微波同步输出的要求。2.对波导滤波型双工器功率容量和传输效率的提高,以及模式的控制进行了研究,实现了两路同波段同极化方向的GW级高功率微波的耦合输出。根据波导TEm0模式的特点,提出了一种高功率波导双工器的设计思想:保持波导不连续性为H面不连续性,通过调整波导高度来增加功率容量,同时不影响高功率微波传输特性。利用此方法,设计了一套过模窄带波导双工器。利用有限元方法的数值仿真研究发现,在9.38GHz和9.60GHz处,两通道微波功率传输效率均高于98%,效率高于90%的通带大于120MHz,功率容量高于6.2GW;低功率实验研究结果表明,在9.38GHz和9.60GHz处,两通道微波能量传输效率均高于97%,效率高于90%的通带大于100MHz。在高功率微波实验中,我们对双工器输出波形进行了测量。根据测量的结果计算得到的微波功率约为4.3GW,脉冲宽度约为40ns,微波频率分别为9.41GHz和9.59GHz。这些结果显示,所设计的过模波导双工器可应用于GW级高功率微波拍波的产生和微波功率的合成。3.根据前面的研究结果,设计了一套利用混合滤波实现高功率微波耦合输出的结构。本文以S/X/X波段3路高功率微波耦合输出为例,验证了混合滤波法的可行性。理论研究的结果表明,当线极化波双工器置于1atm气压SF6气体中时,S/X/X波段3路高功率微波耦合输出的功率容量达10GW以上。进一步的实验研究分别在3.60GHz、9.41GHz和9.59GHz的频率上进行。低功率实验研究表明,在以上工作频率上,各路微波从馈入端口至输出端口的功率传输效率均高于96%;在GW级高功率微波实验研究中,没有发现微波击穿现象。以此初步证明了S/S/C/C/X/X波段6路高功率微波耦合输出的可行性。4.在论文的最后,研究了多路高功率圆极化波耦合输出。对栅条型圆极化器和圆极化波双工器进行了必要的改进,以用于高功率微波的圆极化及其耦合输出。通过理论分析和数值仿真的方法,初步验证了S/X各两路高功率圆极化波耦合输出的可行性。更多还原

【Abstract】 As high power microwave (HPM) technologies gradually matured, the technologies for enhancing the output capacity of HPMs are becoming more and more attractive. Efforts have been made on increasing the output power, pulse duration, conversion efficiency and the frequency spectrum of the HPM devices. However, limited by physics and technology, the approaches for enhancing the output capacity with a single HPM source have encountered difficulties. An alternative method for enhancing the output capacity of HPM sources is taking advantage of coupling output of multichannel HPM sources. In this dissertation, a detailed research on the coupling output of multichannel HPMs is presented. The theoretical and experimental research results reveal that, the research on the coupling output of multichannel HPMs conceives a promising prospect for the development of HPM technologies. The detailed contents and innovative work are listed below.1. The filed-enhancement reduction and spatial-harmonic selection of the spatial-filtering diplexer for linearly polarized microwaves are investigated, and the coupling output of dual-channel gigawatt level HPMs is realized.In the dissertation, the plane wave expansion based mode matching method is employed for the analysis of the spatial diplexer consisting of rectangular rods. Based on this method, the influences of the external dimensions, frequencies of the incident waves, incident angles and the other factors on the performances of the diplexers are obtained. Some experiments on the diplexer consisting of rectangular rods have been carried out in our laboratory. The preliminary experiments reveal that, the diplexer exhibits a good performance for the coupling output of S/X band HPMs, however, affected by the field enhancement of the rectangular rods, when the microwave power increase to 2.0GW with pulse duration of 30ns, the pulse shortening and surface flashover are observed.In order to design a practical diplexer for high power, long pulse operations of S/X band HPMs, a diplexer consisting of cylindrical rods is proposed and employed in the HPM coupling output system. The corresponding rules for selecting the spatial harmonics of the scattered waves generated by the cylindrical-rod array are obtained. In the further low power and high power experiments, the designed diplexer consisting of cylindrical rods exhibits a relatively better performance for the coupling output of S/X band microwaves. The reflection and transmission efficiencies are as high as 97% and 97.5%, respectively. When the diplexer consisting of cylindrical rods is illuminated with 1.8GW HPMs of 100ns duration, no microwave breakdown has been found. For the sake of validating the feasibility of the simultaneous operation of S/X band high power microwaves, the high power performances of the diplexers consisting of cylindrical rods which are immersed in dielectric environment are discussed. The results reveal that, the diplexer consisting of cylindrical rods immersed in SF6 gas is capable of being applied for the simultaneous operation of S/X band HPMs with power level of 5.5GW.2. The enhancement of both the power handling capacity and transmission efficiency and the suppression of the higher order modes in the waveguide-filtering diplexer are studied, and the coupling output of dual-channel gigawatt level HPMs in the same frequency band and polarization direction is realized.According to the characteristics of TEm0 mode, an important concept to enhance the power handling capacity of the waveguide components consisting of H-plane discontinuities by enlarging the heights of the main waveguides without any affects on its transmission properties is proposed. A prototype waveguide diplexer is designed and analyzed systematically by the finite element method. The numerical calculations reveal that, the designed diplexer has its transmission efficiency higher than 98% at 9.38GHz and 9.60GHz, the frequency bands with efficiency higher than 90% are more than 120MHz. The low power experiments show that, the transmission efficiencies are higher than 97% at 9.38GHz and 9.60GHz separately. The frequency band with transmission efficiency higher than 90% is more than 100MHz, which is in agreement with the numerical simulation. In the high power experiments, the radiated powers of the beat waves are measured to be about 4.3GW, 40ns, the frequencies are about 9.41GHz and 9.59GHz. These results demonstrate that, the diplexer is applicable to the generation of GW level beat waves and the power combining of HPMs.3. Based on the previous work, the hybrid filtering method is employed to realize the coupling output of multichannel HPMs. As an example, the coupling output of the S/X/X band HPMs is investigated for the validating of this method. The theoretical analysis reveals that, when the spatial filter is immersed in SF6 of 1atm, the ultimate power handling capacity of the multichannel coupling output system reaches over 10GW. The further experiments are designed for the operations of the 3.6GHz, 9.41GHz and 9.59GHz HPM sources. The low power experiments reveal that, the transmission efficiencies of each channel from the feeding port to the radiating port are as high as 96% for the operation frequencies. When fed with GW level HPMs, there is no obvious microwave breakdown. Thus, the feasibility for the coupling output of S/S/C/C/X/X band six-channel HPMs is preliminarily demonstrated.4. The feasibility for the coupling output of circularly polarized microwaves is discussed in the end. The improved strip circular polarizer and the diplexer for circularly polarized microwaves are employed for the coupling output of circularly polarized HPMs. With theoretical analysis and numerical simulation, the coupling output of S/X band four-channel circularly polarized HPMs is preliminarily validated.更多还原