Study of Mode Coupling on Coaxial Resonators

A study of mode coupling phenomenon of coaxial resonators has been conducted with theories.Through establishing the source-free transmission line equation,boundary conditions of the coaxial resonators with a corrugated inner conductor are analyzed.In the end,calculations are performed in a wide range of corrugation parameters for the resonator of the Karisruhe Institute of Technology (KIT) relevant coaxial gyrotron.     

Study of Eigenmodes of Coaxial Resonators Using Coupled-Wave Theory

Based on the surface impedance theory (SIT) and the coupled-wave theory (CWT), this paper has established the second-order transmission line equation applicable to coaxial resonators with corrugated inner conductor. By utilizing the equation, the resonant frequency, Q factor and field profiles geometry of the eigenmodes of coaxial resonators can be calculated in view of the mode coupling, and the variables of the slot width and depth in the coupling coefficient can also be applied to calculate their impact on the resonant frequency and Q factor. The numerical results show that, the slot width and depth have significant impact on the resonant frequency, but their effect on Q factor is approximately negligible.     

小型介质同轴谐振器的设计与制作

阶梯阻抗结构可以有效地降低同轴谐振器的高度,阶梯阻抗同轴谐振器的各段长度一般是通过求解谐振条件方程式来确定,计算过程繁琐。首次用Smith圆图辅助设计其结构尺寸,非常简单,选择参数相当直观。设计了一中心频率为930MHz,阻抗比为0.172的介质同轴谐振器,其总长度约等于八分之一波长。采用εr=88的微波介质材料制作了实物,并用网络分析仪测试其频率,测试结果与设计数据基本吻合。     

TM模式同轴布喇格结构频率响应研究

基于多波耦合理论,利用Fortran编程软件,以TM模式为工作模式,对工作在太赫兹频段的开正弦槽同轴布喇格反射器的频率响应进行了仿真研究.研究结果表明,在高频高阶TM模式下,竞争模式和所需工作模式带隙之间的带隙重叠可以通过初始相位差的逐渐增大得到明显改善;频响特性曲线的残存旁瓣可通过加窗技术得到有效抑制;加正圆锥或者倒圆锥渐变波纹时,工作模式影响较小,竞争模式会相应地偏离中心频带,对带隙重叠的分离也有一定的影响.研究为同轴布喇格反射器在太赫兹领域以TM模式工作提供了可能性.     

介质同轴谐振器的频率测试方法

介绍了一种测量介质同轴谐振器频率的新方法，即在谐振器的开路端串联一高品质因数Q电容，用标量网络分析仪测出其串联谐振频率，从而得出谐振器的频率。该方法操作简单，对仪表的要求不高，适合于规模生产，特别适合于介质滤波器的调试。     

Semiconductor Heterolasers with Double-Mirror Two-Dimensional Bragg Resonators

Semiconductors - A double-mirror two-dimensional Bragg resonator design based on structures of planar geometry, which is typical of both band-to-band and quantum-cascade heterolasers, is suggested....     

Gold-Plated Micromachined Millimeter-Wave Resonators Based on Rectangular Coaxial Transmission Lines

Resonators based on microfabricated rectangular coaxial (recta-coax) transmission lines are presented. The resonators were fabricated using a multilayered nickel electroplating process that enables the fabrication of three-dimensional structures. As a method to improve performance, gold was plated on the resonators using an electroless process. A model for predicting the effect of the plating on a resonator quality (Q) factor is presented and verified by measurements. Measured resonators show that the plating can increase the Q factor of nickel resonators by over 50% at frequencies above 44 GHz. Utilizing gold plating, 50-Omega resonators are demonstrated at 44 and 60 GHz with unloaded Q factors of 213.1 and 242.3, respectively     

Monolithic Rectangular Coaxial Lines and Resonators With Embedded Dielectric Support

Monolithic rectangular coaxial lines and related transmission line resonators with dielectric support embedded within the body of the inner conductor are demonstrated in this letter. Effects of dielectric straps are thoroughly studied and conclusions are verified through simulations and experiments. A very low-loss of below 0.1 dB/cm and unloaded $Q$ -factors around 400 are measured at Ka-band. It is shown that the high-end performance is maintained for different components distributed across a ${6}^{primeprime}$ wafer.      

Suppression of Residual Side-lobes in a Coaxial Bragg Reflector

This note demonstrates the existence and possible suppression of the residual side-lobes in a coaxial Bragg reflector by employing Blackman window distribution, no matter if the phase difference between the outer and inner corrugations is 0, or π/2, or π. Physical explanation is qualitatively given to the effect of the window distribution.     

A Coaxial Bragg Reflector for Cyclotron Autoresonance Maser Oscillators

A coaxial Bragg reflector is suggested for the application in the cyclotron autoresonance masers (CARMs), where both the outer wall and inner rod are corrugated with weak axisymmetric-sinusoidal-ripple, and a concept design is presented. It is found that, compared to the cylindrical Bragg reflector, the coaxial Bragg reflector has larger dimensional size, narrower bandwidth, and larger eigenvalue intervals. These peculiarities are favorable to the mode selectivity, the ability of dissipating the ohmic heat on the wall, the oscillating startup of the operating mode, and machining manufacture, and therefore, this new kind of Bragg reflector can be developed into a coaxial resonator for the high-power CARMs     

Effect of Eccentricity on Transmission in a Coaxial Bragg Structure

In practice a coaxial Bragg structure always has an eccentricity between the outer-wall and inner-rod axes. Numerical simulations are carried out to analyze the effect of the eccentricity on the transmission in a coaxial Bragg structure. Results demonstrate that the effect of the eccentricity is minimized and becomes negligible when the phase difference between the outer and inner corrugations is π, no matter if the eccentricity is parallel or oblique.     

The Q-Factor of Coaxial Resonators Partially Loaded with High Dielectric Constant Microwave Ceramics

The quality factor of partially loaded dielectric coaxial stepped impedance resonatop (PDSIR) has been analyzed, including analysis of the dielectric constant epsilon/sub r/ and the dielectric loss tan delta of the ceramics. The Q-factor of several resonators is also calculated and compared with the experimental results. This shows that the Q-factor degradation lessens even though the resonator length becomes small when the total length L/sub t/>1//spl radic/epsilon/sub r/ and becomes large when L/sub t/ < 1//spl radic/epsilon/sub r/.     

Self-Referencing Fiber-Optic Intensity Sensors Using Ring Resonators and Fiber Bragg Gratings

An improved ring resonator self-referencing technique in a new reflection configuration for remote fiber-optic intensity sensors is demonstrated using fiber Bragg gratings. Sensor sensitivity doubles and a single fiber lead is used. The sensor is interrogated at two subcarrier frequencies having a high rejection of interference from laser source intensity fluctuations and loss in the fiber lead. We experimentally demonstrate the efficiency of the new reflection configuration, the usefulness of the theoretical model proposed, and discuss design parameters for optimum insertion losses     

A Design Method of Bandpass Filters Using Dielectric-Filled Coaxial Resonators (Short Papers)

Design formulas for capacitively coupled bandpass filters using dielectric-filled coaxial resonators are derived and experimentally verified. The most important advantage of this filter is its ability to provide wide stopband characteristics for harmonics suppression. Its features can be obtained from the configuration using both quarter-wavelength uniform impedance resonators (UIR's) and stepped impedance resonators (SIR's).     

Bragg Reflectors and Resonators in Microstrip Technology Based on Electromagnetic Crystal Structures

Recently, new promising two-dimensional (2-D) Photonic Bandgap Structures (PBG), or more properly Electromagnetic Crystal Structures, for microstrip lines have been proposed. In this paper, we analyze these structures in a manner like a Bragg reflector in optical wavelengths. Joining two of such Bragg like reflectors by means of a conventional microstrip transmission line allows one to design Bragg Resonators. The 2-D periodic pattern of the electromagnetic crystal structure is implemented with circles etched in the ground plane of the microstrip line by means of a numerical milling machine. Simulations have been performed by using HP ^TM Momentum and MDS software, and in accordance with the measurements give, for the Electromagnetic Crystal Structures, new promising potential applications both in microwave and millimeter wave integrated circuits, and also in the experimentation of expensive short wavelength (including photonic) devices by using simpler and cheaper microwave down scaling.     

Singular and Hypersingular Integral Equations Techniques for Gyrotron Coaxial Resonators with a Corrugated Insert

For the first time rigorous theory is developed for eigen traveling TM modes in the resonator of the coaxial cavity gyrotron with a corrugated insert. This mathematical model can be applied for any corrugation parameters and wavelengths. Gyrotron simulation software is developed and allows to calculate mode eigenvalues, electromagnetic field components and Ohmic losses for eigen TE and TM modes. Results of the numerical investigations are presented for the ITER relevant 170 GHz coaxial cavity gyrotron developed in Forschungszentrum Karlsruhe, Germany.     

Effect of Ripple Taper on Coupling Modes in a Coaxial Bragg Structure

Based on the mode-coupling method, numerical analysis is presented to demonstrate the influence of ripple taper on coupling modes on the frequency response in a coaxial Bragg structure. Results show that the interval between the band-gaps of the competing mode and the desired working mode is narrowed by use of a positive taper, but is expanded if a negative taper is employed, and the influence of the negative taper is more obviously advantage than the positive taper. The residual side-lobes of the frequency response on coupling modes can be effectively suppressed by employing the windowing-function technique. These characteristics of a tapered coaxial Bragg structure are favorable to improvement of the performance as a reflector or a filter in its application, also favorable to the mode selectivity and further weaken the excitation of unwanted spurious modes.     

Application of a Microwave Coaxial Bragg Structure for the Measurement of Parameters of Insulators

Journal of Communications Technology and Electronics - A method for the measurement of the complex permittivity of insulators using a microwave coaxial photonic crystal is proposed and implemented....     

Eigenmodes for Straight Circular Cylinder Microwave Resonators Containing a Coaxial Dielectric Sample (Computer Program Descriptions)

This program gives, from an exact analytic theory, either a characteristic parameter of the sample or resonance frequency for all eigenmodes which may exist in the loaded cavity.