环状截面同轴金属波导的特性研究

以电磁场理论为出发点，对满足环状截面同轴金属波导边界条件的麦克斯韦方程组求解，得到了环状同轴波导管内的电磁场各分量方程，并以TE模灰例详尽分析了环状金属波导管中的模式特征、色散关系、光束传播及其强度分布特性。     

四种非矩形截面传感波导中的TE波和TM波

用保角变换将非矩形截面传感波导变换成等效矩形截面波导．给出计算等效矩形截面波导的TE模和TM模、电磁场、临界频率、波导壁电流、功率传输和衰减的公式．并给出4种非矩形传感截面波导数值计算的例子．     

梯形截面脊波导的特性分析

提出了用有效折射率法结合转移矩阵理论对梯形截面脊波导进行数值分析的新方法。对梯形截面脊波导中模式传播常数和模式间耦合系数的分析表明,梯形截面脊波导与稍宽的矩形截面脊波导行为相同。这一结论有利于简化梯形截面脊波导的设计,提高实际器件的精度。     

任意截面光波导的模式计算

提出了一种计算近理想形状任意截面光波导模式特性的方法。首先运用微扰理论计算出光波导的电磁场分布,然后从麦克斯韦方程出发推导出一个计算光波导传播常数的公式并由此得出其色散曲线,该方法没有繁杂的计算过程。     

梯形截面硅脊形波导的模式特性及其等离子体色散效应

本文运用有效折射率法和WKB法对具有梯形状截面的硅脊形波导的模式特性作了分析,导出了TE模和TM模的模方程以及截止方程,并运用一阶微扰法对因波导顶部注入载流子而引起的模式调制的大小作了数值估计。其结果可为全硅光波导器件的研制提供指导。     

矩形截面固体波导中弹性导波模式的板波叠加解

参照板中兰姆波模式的子波叠加解求解了矩形截面固体波导中弹性导波的模式。其中子波设定为横向满足自由边界反射条件、纵向波数分量相同的各板波模式。假设声场的完备性,利用子波模式的正交性,结合矩形截面的几何对称性可以得到4组独立导波特征方程用于频散曲线以及导波模式计算,其计算结果与有限元法计算结果相符。研究以解析模型表明:矩形截面固体波导中的导波是其内部以一定纵向波数分量斜向传播的板波模式在两个自由侧面上经过反复反射与模式转化后,横向耦合谐振而形成的。      

8mm高功率过模弯曲圆波导TE01—TM11模式变换

在模式耦合理论的基础上,采用传统的波导轴线常弯曲和改进的波导轴线正弦弯曲方法,对TE01—TM11模式变换器的几何结构进行优化分析,得到了最优几何参量.以波导轴线正弦弯曲结构设计的8mm高功率圆波导TE01—TM11模式变换器的转换效率达到99%,带宽超过32%.同时还研究了蛇形线圆波导TE01—TE11模式变换器 关键词： 圆波导 弯曲波导 模式变换 耦合波方程     

V波段圆波导TE_(01)模式激励器

V波段圆波导TE01模式激励器由矩形TE10模式到矩形TE20模式变换器和矩形TE20模式到圆波导TE01模式变换器组成。采用H面(磁面)转弯激励的方式实现矩形TE10模式到矩形TE20模式的变换;根据圆波导TE01模式的场分布特性,引入过模波导实现了矩形TE20到圆波导TE01的变换。计算结果表明设计的激励器转换效率在95%以上;模式纯度在98%以上的相对带宽可达4.2 GHz;其中在43.4 GHz处的最大转换效率为99.08%,纯度为99.20%。     

任意截面波导中截止波长测试的一种新方法

 提出了一种测试任意复杂截面波导截止波长的新方法。该方法利用波导及谐振腔的有关理论,把任意复杂截面波导的截止频率测试问题转化为对波导谐振腔的测试,因而不但在测试中回避了匹配和过渡等难题,而且达到较高精度,非常适合于微波工程设计使用。还提出了对波导衰减以及模式场分布的测试方法。     

同轴波导内金属支撑杆的散射特性研究

 对同轴波导内传输TEM模时金属支撑杆的散射特性进行了研究。通过将同轴波导等效为窄边是磁壁的矩形波导,建立了金属支撑杆的散射场计算模型,用积分方程法得到了散射场的计算公式,其计算结果与有限元方法仿真结果吻合良好。分析计算和实验表明：当同轴波导传输TEM模时,n根角向均匀分布的支撑杆在同轴波导内激励起一系列TE(mn)1模式;当n大于同轴波导截面平均周长与波长之比时,金属杆所激励的高阶模截止,输出和反射模式仅为TEM模,其反射系数随支撑杆根数或支撑杆半径的增加而增大,随频率的升高而减小。     

Waveguide Cross Section and Background Magnetic Field Tapers for Broadbanding a Gyro-TWT

The gyro-TWT in a cylindrical waveguide of linearly-tapered cross section was analyzed for the gain-frequency response, using the Pierce-type gain equation. The taper in the waveguide cross section was adjusted for wide device bandwidths, either by changing the taper angle, while keeping the interaction length to be constant, or by changing the interaction length, while keeping the initial and final radii of the waveguide constant. Tapering led to the prediction of wide bandwidths, though at the cost of gain, as compared to a non-tapered device. The range of the DC background magnetic flux density relative to its grazing-point value was identified as a crucial parameter for large gains, with appreciable bandwidths, and minimum mode mixing in a tapered device, the latter in general facing more mode competition than a non-tapered device.     

Magnetic-Type Waves in a Tapered Waveguide of Subwavelength Cross Section

The characteristics of electromagnetic waves in a narrowing waveguide are investigated. A method for field analysis is developed based on the application of transverse modes parametrically dependent on the longitudinal coordinate. For a circular cross section waveguide, a system of equations for the wave amplitudes is obtained, the waves being coupled owing to a variable tilt of the walls. It is shown that in the adiabatic approximation, there exist independent eigenwaves whose structure reflects the field energy density variation due to the waveguide radius variation. A detailed analytical and numerical investigation of these fields has been carried out for a waveguide with a special profile of hypergeometric type. The applicability of the adiabatic approximation is studied and conversion of the fundamental mode into higher-order modes is assessed. The amplitudes of the higher-order modes are obtained using the Green function for ordinary differential equations. The region of the waveguide parameters is found where the higher-order mode amplitudes are not great and the adiabatic approximation is highly accurate. The dependence of the transmittance of a semi-infinite waveguide on the input radiation characteristics is obtained. It is established that the field amplitudes at the waveguide output strongly depend on the wavelength of the input radiation, on its transverse structure, and the waveguide profile steepness. The greatest output fields take place in the case of an abrupt dependence of the waveguide radius on the longitudinal coordinate.     

Retardation Effect and Dark State in a Waveguide QED Setup With Rectangle Cross Section

This paper investigates the dynamics of two two-level atoms, which simultaneously couple to a quasi-1D waveguide with rectangular cross section. The waveguide modes serve as environment, which induces the interaction and collective dissipation between the two distant atoms. When both of the two atoms are located in the middle of the waveguide, a retardation effect is observed, which can be broken by moving one of the atoms away from the center of the waveguide. To preserve the complete dissipation of the system via dark state mechanism, a scheme where the connection of the atoms is perpendicular to the axis of the waveguide is proposed.     

Field Structure in the Cross Section of a Ferrite Inhomogeneous Anisotropic Insert of a Rectangular Waveguide

We develop a physico-mathematical model describing excitation and distribution of electromagnetic waves in an anisotropic waveguide or resonator in the three-dimensional case. We develop a theoretical approach for discretization of the Maxwell equations in an arbitrary medium in the presence of bounding walls of a waveguide or resonator. The resulting system of linear algebraic equations for the electric-field components in an inhomogeneous anisotropic medium is solved by the method of biconjugate gradient. The results of calculating the electric field lines in the cross section of an anisotropic insert of a rectangular waveguide are presented.     

大截面SOI脊型波导单模条件的研究

利用有限差分方法（FDM）对大横截面SOI（Silicon-on-insulator）脊型光波导的本征模进行了计算分析, 从而确定了SOI脊型波导的单模条件, 即归一化外脊高和归一化脊宽的关系. 通过比较, 进一步明确了归一化外脊高大于0.5时现有的单模条件解析公式中常数项的取值为0.3. 同时, 还对归一化外脊高小于0.5时的单模条件也做了计算和讨论.     

Slow Wave Characteristics of Helix Structure with Elliptical Cross Section

We present a novel helix slow wave structure with an elliptical cross section shielded by an elliptical waveguide. The rf characteristics including dispersion properties, interaction impedance of zero mode in this structure have been studied in detail. The theoretical results reveal that weaker dispersion even abnormal dispersion characteristics is obtained with the increasing eccentricity of the elliptical waveguide, while the interaction impedance is enhanced by enlarging the eccentricity of elliptical helix.     

单模光纤色散的解析形式

根据波导标量解本征值方程及其递推关系,提出一种利用Gloge关系求解单模光纤中波导色散的理论方法,给出了色散的解析形式,通过分析归一化传输常数的近似解与精确解间的差别论证了这种解析法具有精确求解的计算精度,给出普通单模光纤（G．652）光纤色散的实验数据,并与计算的色散解析解曲线加以比较,二者达到极好的吻合,利用所得到的结果,分析了数值微分法和经验公式的计算精度。     

Isotope Dependence of Superheavy Nucleus Formation Cross Section

The dynamical process in the superheavy nucleus synthesis is studied on the basis of the two-dimensional Smoluchowski equation. Special attention is paid to the isotope dependence of the cross section for the superheavy nucleus formation by means of making a comparison among the reaction systems of ^54Re＋204pb, ^56Re ＋206Pb, and ^58Fe＋^208Pb. It is found by this comparison that the formation cross section is very sensitive to the conditional saddle-point height and the neutron separation energy of the compound nucleus. Reaction systems with lower height of conditional saddle-point and smaller neutron separation energy are more favourable for the synthesis of the superheavy nucleus.     

Computing Eigen value equation and modal dispersion characteristics of an elliptical Bragg waveguide

Using the method of separation of variables in the elliptical coordinate system, a recursive formula for the electromagnetic fields in a new type of Bragg waveguide having elliptical core cross section with multilayered cladding is derived. The eigen equation is written in the form of Mathieu and the modified Mathieu functions and a dispersion relation is obtained for various modes supported by the proposed Bragg waveguide. The cutoff frequencies for several lower order even-odd modes have been calculated and their propagation characteristics are plotted. The results show that the dispersion curves are discontinuous and modes can exist only in particular wavelength bands. The effects of elliptical eccentricity on the mode cutoff values and mode transmission are addressed. Finally, the modal birefringence in the said waveguide is also estimated.     

轻丰中子核反应中子集团产生截面的理论研究

采用Boltzmann-Langevin方程研究了能量为35MeV/u的¹⁴Be, ⁸He,⁶He,¹¹Li,¹⁷B,¹¹Be,¹⁹C与¹²C靶的反应,计算了产生中子集团的截面, 发现^14,Be与¹²C靶反应产生⁴n的截面与实验值符合得很好. 通过这几个入射核与¹²C靶形成中子集团截面的对比, 发现核的晕中子越多产生中子集团的截面越大, 晕中子数相同时, 质量数越大产生中子集团的截面越大.中子集团可能主要来自晕核子.