A Rotary Joint for Two Microwave Transmission Channels of the Same Frequency Band

This paper describes a rotary joint for two microwave transmission channels of the same frequency band. It consists of two pairs of rectangular waveguide terminals, a circular waveguide which transmits both channels, and coupling elements between the rectangular waveguide terminals and the circular waveguide which convert the rectangular H/sub 10/ mode into the circular H/sub 01/ and E/sub 01/ modes. If pure H/sub 01/ and E/sub 01/ modes can be excited, perfect separation of the channels as well as constant amplitudes and phases can be obtained when the joint rotates. While the conversion into the circular E/sub 01/ mode is performed by a conventional method, a new method had to be developed for the conversion of the rectangular H/sub 10/ into the circular H/sub 01/ mode.     

脊双模波导滤波器的分析及设计

介绍了一种能实现脊双模波导滤波器的新型结构,分析了其腔内模式的耦合极性,利用不同的耦合极性对频率响应的影响可实现具有一对传输零点的双模滤波器,也可实现无传输零点的双模滤波器.以相同脊谐振单元不同的放置方向组成的两种带通滤波器为例,利用AnsoftHFSS仿真得到了两种不同的频率响应,结果与理论分析一致.最后设计出了一个六阶三传输零点的双通带滤波器,带内插损均小于0.6 dB,回波损耗小于-15 dB.     

Dual mode coupling by square corner cut in resonators and filters

A method for realization of dual-mode coupling in rectangular waveguide cavities is described and analyzed. The method completely replaces the coupling screw, and therefore can be used to eliminate the need for tuning in dual-mode waveguide cavity filters. It also offers a wide range of coupling values and can achieve higher power-handling capability than coupling screws. Mode matching is used to calculate the mode chart of the infinitely long square corner cut rectangular waveguide (SCCRW), the field distributions of each mode, and the resonant frequencies of the cavity. An evanescent mode rectangular waveguide is used to provide dual-mode couplings between adjacent cavities. The junction discontinuity between the SCCRW and the rectangular waveguide is modeled by a double mode-matching method, yielding modal scattering parameters of the junction. A four-pole dual-mode elliptic-function rectangular waveguide cavity filter using the coupling method was constructed. The experimental filter results showed excellent agreement with theory     

Measurement of Two-Mode Discontinuities in a Multimode Waveguide by a Resonance Technique

The deliberate use of two or more propagating modes in a multimode waveguide, and a knowledge of associated control elements, has assumed renewed importance, particularly for millimeter wavelength applications. This paper presents a resonance measurement technique for the precise evaluation of the equivalent network for a lossless shunt discontinuity coupling two nondegenerate modes in a multimode waveguide. The discontinuity structure is placed into a cavity closed by adjustable plungers, and the data consists of those plunger positions which render the cavity resonant in the two modes of interest. This multipoint data is then transformed to permit an analysis of the two-port network in the discontinuity plane by conventional techniques. Computations and experimental results obtained at S band illustrative of the procedure are presented for shunt discontinuities coupling the E/sub 01/ and H/sub 01/ modes in circular waveguide. The accuracy achieved is comparable to that obtained in single mode precision measurements.     

Hyperbolic Secant Coupling In Overmoded Waveguide

This work presents a new solution of the coupled-mode equations for a hyperbolic secant spatial variation of the coupling between two modes. An analytic expression is given for the transmission coefficient for arbitrary complex differential propagation constant and coupling strength. The expression is particular simple in the case when the differential attenuation between the modes is negligible. Design curves are presented in terms of normalized parameters. The hyperbolic secant coupling may be truncated and still yield virtually the same transmission as for infinite couping length. The required coupling length is indicated by a comparison of the ideal expression with the results of numerical integration of the coupled-mode equations. Hyperbolic secant coupling can be particularly useful for the design of short low-loss broad-band bends, twists, and mode-selective couplers in overmoded waveguide. Results of tests on 90-degree bends in rectangular and corrugated circular waveguide are consistent with the theory.     

EMI from cavity modes of shielding enclosures-FDTD modeling andmeasurements

Electromagnetic interference (EMI) from slots and apertures resulting from coupling of interior sources through enclosure cavity modes in a rectangular test enclosure is reported. EMI from a specially designed test enclosure with slots or apertures excited by interior sources was studied experimentally and with finite-difference time-domain (FDTD) modeling. The measurements and FDTD modeling agree well. The results indicate that radiation at cavity mode resonances through slots and apertures of nonresonant dimensions can be as significant as the radiation at aperture or slot resonances. The agreement between the FDTD modeling and measurements demonstrates the usefulness of FDTD for investigating aspects of shielding enclosure design such as coupling to slots and apertures and slot interactions     

双层亚波长金属栅的电磁波透射抑制效应

基于传输矩阵法计算了完美电导体双层亚波长金属栅的透射谱,分析了其透射抑制现象,并结合场分布特点建立了等效的矩形腔模型,获得了透射抑制发生时的结构参数及波长的依赖关系.结果表明,透射抑制现象与组成的单栅厚度无关,不依赖于单栅的波导模式,主要取决于两栅间隔内的倏逝模耦合,场分布表明此时第二层栅的狭缝入口处为零场分布.基于完美电导体的矩形腔模型,给出了场分布的解析解,并进一步计算出与透射谱上透射抑制线较为吻合的结果.     

Resonant Cavity Type Mode Transducer

This paper describes the operating principle and the properties of a resonant cavity type mode transducer which was newly devised. The theoretical equations necessary for designing the mode transducer from a TE/sub 10/ mode of a rectangular waveguide to an arbitrary mode of a circular waveguide have been derived, and a design method using the coupling parameters is discussed. The experiments were made for the rectangular TE/sub 10/-circular TE/sub 01/, mode transformation in the 50 Gc band. Showing an example (N=1), the transfer loss, input SWR and mode purity were 1.34 dB, 1.13, and 95 percent (power contents), respectively, at the resonant frequency of 50 Gc/s. The 3 dB bandwidth of the transfer loss was 83 Mc/s at the constant cavity length, but it can be made much larger if the cavity length is adjusted according to the frequency change. This mode transducer is unique in that various modes can be excited purely in the circular guide by merely varying the cavity length.     

A dielectric rod waveguide coupled with metal rectangular waveguide

Measurements have been done in the millimeter wave region on a composite waveguide which comprises a dielectric rod waveguide connecting two metal rectangular waveguides. Such a waveguide has been used by us in a Josephson harmonic mixer installed in a small metal cryostat, to prevent the thermal invasion from outside environment and to transmit both signal and LO waves with small losses. The measured transmission loss, that is caused mainly by the coupling loss between metal rectangular waveguides (TE₁₀ mode) and a dielectric rod waveguide (HE₁₁ mode), has been less than 2dB in the frequency range of 52–104 GHz.     

A shorted waveguide-stub coupling mechanism for narrow-band multimode coupled resonator filters

A shorted waveguide-stub coupling mechanism is presented for implementing narrow-band multimode coupled cavity filters without coupling screws. The coupling element is a shorted rectangular waveguide stub placed in the end walls of cylindrical filter cavities, using perturbation of the magnetic fields to obtain coupling between degenerate modes. This structure is well suited to analysis and design with the efficient and accurate mode-matching method. Coupling coefficients and resonator frequencies can be controlled by varying cavity dimensions and the length, width, and depth of the rectangular coupling element. The accuracy with which the coupling can be realized and the elimination of coupling screws reduce the amount of tuning substantially. A third-order Chebyshev filter, realized in a triple-mode cavity with no coupling screws and only two tuning screws, is presented to verify the use of the coupling structure.     

Propagation in a Dielectric-Loaded Parallel Plane Waveguide

A theoretical analysis of wave propagation in a parallel plane waveguide partially filled with a dielectric is performed. This transmission line is a symmetrical three-region structure consisting of two infinite parallel conducting planes with a dielectric slab of rectangular cross section between and contacting each of the planes. It has been found that TEM and TM modes cannot propagate on this structure. This investigation is concerned with TE modes, although hybrid modes can also propagate on this line. The lowest order TE mode, which is the dominant mode, has no cutoff and hence is inherently suited to extremely wide bandwidth operation. Equations have been presented for the field components, guide wavelength, cutoff criteria, power handling capabilities, wall losses, and dielectric losses as a function of the operating wavelength, waveguide dimensions, and material constants. In the case of the dominant mode, design curves covering a large range of wavelengths, dimensions, and dielectric constants are presented. For a loosely bound wave, the losses are comparable or less than those of conventional rectangular waveguide and the power handling capacity is an order of magnitude greater.     

Wave Scattering in Nonuniform Waveguides with Large Flare Angles and Near Cutoff

A set of coupled first-order differential equations for the wave amplitudes in nonuniform waveguides is developed. The coupling coefficients are regarded as differentiaI transmission and reflection scattering coefficients between two adjacent elementary radial waveguide sections. The analysis is an extension of an earlier quasi-optical solution. This set of coupled equations is compared with the familiar generalized telegraphist's equations which may be derived by considering the nonuniform waveguide to consist of elementary rectangular waveguide sections. The equations for the wave amplitudes derived in this paper are less coupled than the commonly used telegraphist's equations, and they may also be applied to waveguides with large flare angles and in regions at which the waveguide modes are at their respective cutoff cross sections.     

A fast multiple mode intermediate level circuit model for the prediction of shielding effectiveness of a rectangular box containing a rectangular aperture

This paper presents an intermediate level circuit model (ILCM) for the prediction of the shielding effectiveness (SE) of a rectangular box containing a rectangular aperture, irradiated by a plane wave. The ILCM takes into account multiple waveguide modes, and is thus suitable for use at high frequencies and/or relatively large boxes. Inter-mode coupling and reradiation from the aperture are taken into account. The aperture may be positioned anywhere in the front face of the box, and the SE at any point within the box may be found. The model is presented in such a way that existing ILCM techniques for modelling elements such as monopoles, dipoles, loops, or transmission lines may be seamlessly incorporated into the circuit model. Solution times using the ILCM technique are three orders of magnitude less than those required by traditional numerical methods such as FDTD, TLM, or MoM. Accuracy however is not significantly compromised. Comparing the circuit model with TLM over nine data sets from 4 MHz to 3 GHz resulted in an rms difference of 7.70 dB and mean absolute difference of 5.55 dB in the predicted SE values.     

Eigenmode confinement in the dielectrically apertured Fabry-Perot microcavity [VCSEL]

The three-dimensional (3-D) optical confinement of the dielectrically apertured Fabry-Perot microcavity is analyzed by considering electromagnetic coupling between the confined region and parasitic waveguide modes that exist outside the aperture. If the cavity length is close to one-half the emission wavelength and for large enough aperture sizes, all parasitic waveguide modes can be evanescent except one which couples only weakly to the emitting region. If the aperture diameter is too small, loss of optical confinement is predicted, and the optical mode size at which this occurs can be estimated from the cavity length and the relative shifts in the vertical resonances inside and outside the apertured region.     

A new model for microwave characterization of composite materialsin guided-wave medium

A method of determining the permittivity and the permeability of heterogeneous materials from microwave measurements in a coaxial line or in a rectangular waveguide is presented. Fluctuations are observed in the curves of the transmission and reflection coefficients measured in a guided space cell which are caused by the propagation of modes higher than lowest order. The measuring cell containing the sample is represented by an unperturbed line in series with resonators which model the coupling between the sample and the measurement cell for each higher mode resonating inside the sample. Finally, the intrinsic characteristics of the material are computed from the data for the unperturbed line. Results for several composite materials and measurement cells are presented to demonstrate the capabilities of this model     

速调管输出腔高阶TM模式间隙阻抗的模拟计算

该文由功率-电压法和LC等效电路法的概念出发,利用电磁场软件ISFEL3D的后处理文件PAC3D中逐点提取的电磁场强度及其积分值,计算了同轴腔高阶TM310模式与矩形波导基模耦合时,腔内漂移管中心的间隙阻抗,两种方法给出相同的计算结果。对于相同的模式,采用编程计算的结构参数模型可以得到较大的间隙阻抗实部。     

矩形π-TM310 双间隙腔加载同轴滤波器型宽带输出电路研究

本文提出了矩形π-TM310 双间隙腔加载同轴滤波器型宽带输出电路,并对其可行性进行了论证,对高次模双间隙腔中非工作模式的干扰程度和同轴线输出电路的功率容限等重要问题做了定量分析。我们通过调整矩形双间隙腔的长宽比例并采用凹入结构,明显扩大了π-TM310模与相邻非工作模的频率间隔,有效抑制了非工作模式的干扰;又采用了非常规的电子注孔布局,使各个电子注孔的特性阻抗更均匀,而且在加载同轴滤波器之后仍然很均匀。研究结果表明,经过优化设计的矩形π-TM310 双间隙腔加载同轴滤波器型输出电路具有很宽的输出频带,在X波段相对带宽达到14%左右。但由于π模双间隙腔与同轴线的耦合口较小,而且该处还有短路销钉,导致其输出功率容限较低,约为几百kW。因此,该类输出电路比较适合于X波段或更高频段的中功率宽带多注速调管。     

A Complete Solution of the Inductive Iris with TE/sub k0/ Incidence in Rectangular Waveguide

A TE/sub k0/ wave incident on an inductive metal iris in a rectangular waveguide excites a reflected and a transmitted wave in the TE/sub k0/ mode. The reflection and transmission coefficients describing these waves are computed. In addition to the incident mode, a number of other modes are excited by the discontinuity. The amount of coupIing to these other modes, given by coupling coefficients, is determined using the variational technique. The method developed makes it possible to find the coupling to any desired mode without first finding the coupling to any other mode or group of modes. The analysis shows under what conditions certain modes can be suppressed or eliminated. The method should be applicable to other problems of interest where modes other than the incident one are excited. Since the reflection, transmission, and coupling coefficients are known, the total field at any point in the waveguide can be computed. As an example, the total field at the discontinuity when the TE/sub 10/ mode is incident is calculated. The result closely resembles the expected result (of zero electric field over the metal iris).     

基于双层扇形基片集成波导的双频平衡滤波器

提出了一种表面刻有一对互补开环谐振器(CSRR)的45°扇形基片集成波导谐振腔(SSIWR),设计并制作了一款结构紧凑且具有高选择性的双层双频平衡带通滤波器.分别利用具有带通特性的CSRR和谐振腔内的TM220模实现了差模双频响应;模式间的耦合以及缺陷地结构(DGS)的引入使得滤波器在通带附近产生4个传输零点,提高了带...     

Mutual coupling in finite coplanar rectangular waveguide arrays

Mutual admittance expressions are given for all possible combinations of mode coupling in an array of identical collinear rectangular waveguides opening into an infinite ground plane. Specific results are presented for the worst case of E-plane coupling between identical square waveguide to show that significant high-order mode excitation can occur. Some of these modes are a source of crosspolarisation, making mutual coupling important to the prediction of the crosspolar pattern of a rectangular waveguide array.