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《Microwave Theory and Techniques》1981,29(9):942-948
A general approach to the analysis of microwave planar structures, specifically intended to account for radiation loss is presented. By expanding the internal electromagnetic (EM) field in terms of resonant modes, also the external field is obtained in the form of a series, each term of which corresponds to the field radiated by a resonant mode excited in the structure. Neglecting the effect of the thin dielectric substrate on the power radiated and the coupling between the modes, occurring at the lateral surface of the structure, a simplified formulation is obtained which is shown to be in very good agreement with experiments, performed in the frequency range 2-12.4 GHz, which could not be explained on the basis of a Iossless model. 相似文献
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家用微波炉内磁控管的频率会有波动,且难以测定。为考查微波频率波动对样品温度分布的影响, 获得更加精确的仿真结果,研究假设家用微波炉的频率以2. 45 GHz 为中心波动,并对不同波动范围的频率(2.44~2.46 GHz,2.43~2.47 GHz,2.41~2.49 GHz)与单个频率(2.45 GHz)的基于有限元模型的仿真结果与实验结果进行了比较分析。实验对象是放置于微波炉内加热60 s 的土豆泥。对于不同的频率范围分布,每隔0. 005 GHz 计算一次电磁功率密度,并根据余弦分布对它们进行加权平均,最后将电磁功率作为热源加热土豆泥。模拟结果分别与用热成像仪和光纤热电偶测定的土豆泥表面温度分布和各部位瞬时温度的实验值进行比较。结果显示频率波动范围在2.44~2.46 GHz 预测的温度场与实验值有较好的一致性;而在2.41~2.49 GHz 范围内,温度分布的均匀性最好。该模型也可为指导微波食品的开发提供理论依据。 相似文献
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采用径向+轴向模式匹配法完成了蓝宝石回音壁的模式分析,包括高次回音壁模式谐振频率的计算和电磁场分布,并研究了回音壁模谐振器的金属腔体设计等关键问题。制作的高Q蓝宝石谐振器在10.99GHz处,有载Q值达到了45000、插入损耗小于9dB。谐振器性能指标优越,非常适合应用于低相位噪声振荡器设计中。 相似文献
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A two-port ring resonator is used to characterize the microwave properties of a microstrip line printed on Ferro A6-S low-temperature co-fired ceramic. The ring and its coupling gaps are simulated using a simple lumped-element model. The coupling gaps are modeled as capacitors, the values of which are extracted using a commercial two-and-one-half-dimensional electromagnetic simulator. The validity of the lumped-element model is assessed by comparing the simulated and experimental resonant frequencies and, for the first time, the simulated magnitudes of both the reflection and transmission coefficients are also compared with those obtained experimentally. A correction for the frequency pushing due to the capacitive loading of the coupling gaps is also presented. The resulting model is then shown to predict the resonant frequencies to within 0.11% from 5 to 40 GHz. The simulated and experimental reflection magnitudes are within 0.5 dB across the band, whereas the transmission magnitudes are within 3.5 dB up to 22 GHz. Experimental results indicate that the loss of the microstrip ranges from approximately 0.11 to 0.42 dB/cm across the band and that the relative permittivity of the substrate is nearly constant versus frequency with an average value of 6.17. 相似文献
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为了提高器件微波输出功率和功率转换效率,设计了一种四腔结构L波段阶梯阴极磁绝缘线振荡器,运用开放腔高频分析方法得到了谐振频率和高频电场分布,并计算得到了器件的有载品质因数。运用粒子模拟方法对器件进行研究,典型的粒子模拟结果为:在束压为578kV和束流为46.5kA条件下,得到功率为5.1GW的微波输出,工作频率为1.21GHz,功率转换效率为18.9%。最后讨论了电压变化对器件的功率转换效率和频率的影响:器件工作频率受电压变化影响较小;功率转换效率受电压影响较大,在电压为667kV时效率达到最大值20.45%。 相似文献
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Long Yang Draving S.D. Mars D.E. Tan M.R.T. 《Solid-State Circuits, IEEE Journal of》1994,29(5):585-595
This paper describes the design, circuit simulation, fabrication and testing of a 50 GHz trigger circuit using GaAs/AlAs resonant tunneling diodes. A new trigger circuit was designed to eliminate the 180° phase splitter used in a previous complementary input trigger circuit. Our monolithic approach, integrated GaAs/AlAs resonant tunneling diodes (in a back-to-back configuration) and a 50 Ω coplanar waveguide, minimized the parasitic circuit elements and internal reflections from the package thus achieving high frequency operation. The circuit was able to trigger on input sinusoidal waves of input powers of -3 dBm up to 50 GHz with time jitter of less than 1 ps rms over the entire measured frequency range from 5 to 50 GHz. The upper limit of 50 GHz was imposed by our measurement system 相似文献
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通过计算电磁波在不同人体组织分界面的入射情况,研究人体信道电磁波跨越不同组织分界面时的传播特性.文章首先利用电磁场边界条件推导均匀平面电磁波向单层与多层导电媒质入射时的反射系数、透射系数及电磁波表达式;然后以人体手臂为研究对象,采用4阶Cole-Cole模型获取10 Hz~100 GHz人体组织介电参数,计算向单层、多层组织入射时各个分界面上的最大入射角、反射系数、透射系数与平均能流密度,结果显示,垂直入射是电磁波透射多层人体组织的主要路径,皮肤与空气分界面的反射系数最大,频率小于1 MHz或大于10 GHz的电磁波能量比较难在人体内外传播,电磁波平均能流密度传播随频率呈带通特性,带宽及中心频率与器件植入位置有关等;最后采用COMSOL Multiphysics建立电磁波向3层人体组织垂直入射的有限元仿真模型,仿真结果与理论计算结果相比误差小于0.000 08,验证了理论推导与计算的正确性. 相似文献
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Guy Arthur W. Webb Michael D. Sorensen Carrol C. 《IEEE transactions on bio-medical engineering》1976,(5):361-371
When the body of man, small compared to a wavelength, is exposed to high frequency (HF) electromagnetic (EM) fields, the absorbed power density patterns and total absorbed power may be approximated by the simple superposition of the internal electric fields obtained from the quasistatic coupling characteristics of the electric and magnetic field components determined independently. These characteristics were obtained for full scale man by thermographic studies of power absorption in scale models of man exposed to fields at frequencies scaled up inversely proportional to the model size. A VHF resonant cavity was used to provide the necessary field strengths for producing measurable power absorption patterns under simulated HF exposure conditions. The results indicate that peak power absorption densities as high as 5.63 W/kg can be produced in man exposed to 10 mW/cm2 31 MHz radiation fields. The results show that the absorption decreases as the square of the frequency as predicted by theory for frequencies below 31 MHz. 相似文献
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M. V. Datsko A. A. Bakhtin A. V. Tikhomirov A. S. Volkov A. E. Liseitsev A. A. Leont’ev S. D. Chaplygin 《Journal of Communications Technology and Electronics》2018,63(7):778-781
An experiment on the study of waveguide propagation of surface electromagnetic waves with a frequency of 1 GHz in an enclosed space on free curved metal–dielectric interface was conducted. The distribution of the field of the electromagnetic wave along the propagation path was obtained for two cases: when a metallized tape was placed between radiating and receiving antennas and without the tape. It has been found that the field strength in the presence of the metallized tape is higher than the field strength without the tape. 相似文献
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Equations of motion for a free-electron laser with an electromagnetic pump field and an axial electrostatic field 总被引:1,自引:0,他引:1
The equations of motion for a free-electron laser (FEL) with an electromagnetic pump field and a static axial electric field are derived using a Hamiltonian formalism. Equations governing the energy transfer between the electron beam and each of the electromagnetic fields are given, and the phase shift for each of the electromagnetic fields is derived from a linearized Maxwell wave equation. The relation between the static axial electric field and the resonant phase is given. Laser gain and the fraction of the electron energy converted to photon energy are determined using a simplified resonant particle model. These results are compared to those of a more exact particle simulation code. 相似文献
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Bedini Luigi Bramanti Mauro Denoth F. 《IEEE transactions on bio-medical engineering》1980,(11):623-630
In this paper the electromagnetic interaction between a resonator and a lossy dielectric body is examined by means of a simple model suitable for computer simulation; the body was assumed to have a revolution form and the resonator was electromagnetic coupled to the body by its inductive element constituted by a planar circular or spiral coil. On the basis of the model a computer program was derived which allows a simple numerical evaluation of the variation in the resonant frequency caused by the interaction mentioned above. 相似文献
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This paper, the first of two parts, presents an electromagnetic model for membrane microelectromechanical systems (MEMS) shunt switches for microwave/millimeter-wave applications. The up-state capacitance can be accurately modeled using three-dimensional static solvers, and full-wave solvers are used to predict the current distribution and inductance of the switch. The loss in the up-state position is equivalent to the coplanar waveguide line loss and is 0.01-0.02 dB at 10-30 GHz for a 2-μm-thick Au MEMS shunt switch. It is seen that the capacitance, inductance, and series resistance can be accurately extracted from DC-40 GHz S-parameter measurements. It is also shown that dramatic increase in the down-state isolation (20+ dB) can be achieved with the choice of the correct LC series resonant frequency of the switch. In part 2 of this paper, the equivalent capacitor-inductor-resistor model is used in the design of tuned high isolation switches at 10 and 30 GHz 相似文献
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基于螺旋交指结构设计了一种新型的带阻谐振单元,并采用全波仿真软件对其进行分析。仿真结果表明,在此谐振单元中存在2个较窄的阻带,改变单元结构的尺寸可分别控制2个阻带的位置。在此基础上,采用2个单元级联的方式设计并加工了一款具有优越电磁性能的结构紧凑的双频带阻滤波器。采用矢量网络分析仪对所设计的滤波器进行测试,测试和仿真结果吻合较好,2个阻带的中心频率为3.30GHz和4.93GHz,对应的阻带带宽分别为3.233.37GHz和4.733.37GHz和4.735.10GHz,阻带边缘陡峭度大于90dB/GHz,所设计的带阻滤波器具有优越的性能。此外,该滤波器的有效尺寸为24.0mm×5.2mm,与传统带阻滤波器相比较,小型化优势明显。 相似文献
17.
Robinson M.P. Clegg J. Marvin A.C. 《Electromagnetic Compatibility, IEEE Transactions on》2006,48(2):304-310
Radio frequency propagation in an electrically large resonant chamber (a screened room) was simulated by two models: a statistical combination of multiple resonant modes and a computational electromagnetic simulation [the transmission line matrix (TLM) method]. The purpose of this work was to investigate the effects of passengers and windows on electromagnetic fields (EMF) in aircraft and other vehicles. Comparison of the multimode models with measurements made in a screened room showed that as the electromagnetic losses increased, the transmission between two internal antennas was reduced, and there were fewer turning points in its frequency response. The autocorrelation of this frequency response provided a useful estimate of the composite Q-factor of the resonances and showed that the Q of the chamber was reduced from a value of the order of 10 000 when emptied to 1000 when windows were added and when filled with people to 100. The TLM simulation provided further useful information about the statistical variation of electric field strength with position. 相似文献
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RCS of a partially open rectangular box in the resonant region 总被引:1,自引:0,他引:1
The radar cross section (RCS) of a partially open rectangular box in the resonant region is investigated. Two-dimensional numerical results are generated using the method-of-moments solution to the electric field integral equation. Resonance spikes are found in the RCS spectrum at frequencies which correspond to the resonant frequencies of the interior rectangular cavity. The dependence of the resonant behavior on the box dimension, aperture size, and incident polarization can be interpreted in terms of the field distribution inside the cavity. Experimental data for a three-dimensional box are also presented. They are consistent with the two-dimensional simulation 相似文献
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实验测量了神光-III原型装置上脉冲强激光与金属靶相互作用产生的电脉冲辐射,电脉冲峰值梯度为3 kV/m,频谱范围大约在50 MHz?2 GHz,在160 MHz等处有明显的特征峰,信号持续时间大约60 ns。本文研究表明电偶极辐射是打靶过程产生电磁脉冲信号的来源之一,由理论模型计算得到频率为160 MHz的特征峰,并计算出探测点电场脉冲峰值梯度约为2 kV/m,辐射总功率约105 W,能量转换率约10-6,辐射功率近似正比于激光能量的4/3次方,可见激光能量越大,功率密度越高,电脉冲的辐射强度越大。大型激光装置上的激光与靶作用产生的电磁脉冲测量,对大型激光装置产生的电磁辐射的防护有重要指导作用,在等离子体诊断等领域也有潜在应用价值。 相似文献