Thick circular iris in a TE11 mode circular waveguide

The TE₁₁-mode excitation of a concentric circular iris of finite thickness in a circular waveguide is analyzed by Galerkin's method with even and odd excitation. Agreement between calculated and measured dominant mode scattering parameters is generally within experimental accuracy     

Thick eccentric circular iris in circular waveguide

Other researchers have observed that eccentric irises possess certain advantageous features that may lead designers to prefer them over the conventional concentric irises. The least-squares boundary residual method (LSBRM) is utilized in this paper to analyze the behavior of such an eccentric-iris structure (of nonzero thickness). Tests have confirmed that the computer model thus obtained is capable of yielding numerical results that are accurate to within ⊥1%     

Modellization of losses in TE011-mode waveguide bandpassfilters

A mode-matching technique for the analysis of TE₀₁₁ mode waveguide cylindrical bandpass filters including losses is presented. The modes of a lossy radial waveguide are derived and the generalized scattering matrix of the lossy cavity coupled by two rectangular apertures is computed enforcing an impedance boundary condition on the cavity sidewall. Cavity sidewall losses as well as top and bottom wall losses are therefore taken accurately into account. Numerical and experimental results are given for a four cavity filter in Ka band     

使用模式兼容OADM的双LP11模CO-OFDM信号传输方法

介绍了一种使用模式兼容的OADM(光分插复用器)的双LP11模相干OFDM(正交频分复用)信号传输方法。该OADM采用薄膜滤波器和双反射机制实现模式复用的光信号的插分功能。实验结果表明,对于3×318Gbit/s的OFDM信号,OADM在插、分与直通端口的功率代价分别为2.6、2.4和0.7dB。     

Difference between the TM11 mode in a circular and elliptical waveguide

The letter deals with the stability and field configuration of the TM11 mode in a circular and elliptical waveguide. Some numerical results illustrate the variation of the position and value of the maximum electric field in the longitudinal direction as a function of the eccentncity of the cross-section.     

A single-period TE02-TE01 mode converter in ahighly overmoded circular waveguide

A single-period 60 GHz TE₀₂-TE₀₁ mode converter for use in an electron cyclotron heating (ECH) system for magnetically confined plasmas is presented. The mode converter is very compact and has a broad bandwidth and a theoretical conversion efficiency of 97.6%. A method of computing the reflection from converters is presented and used to show that reflection from the single-period mode converter is minimal. Experimental results are consistent with theoretical calculations     

Input mismatch of TE11mode coaxial waveguide feeds

The reflection characteristics of the TE11mode in a coaxial waveguide antenna due to mismatch at the radiating aperture are described. Results are presented for conventional coaxial waveguide as well as waveguide whose inner conductor extends beyond the aperture plane. Coaxial wavegulde mismatch is often quite large, particularly for conditions of good pattern symmetry, and some matching is usually required. A broad-band matching technique using annular rings inside the waveguide is described for the case where there is no external conductor. Results presented show excellent agreement between theory and experiment.     

Ka波段紧凑型TE01-TE11椭圆波导模式转换器的研究(英文)

本文对椭圆波导TE₀₁-TE₁₁模式转换器进行了研究。选择了合适的椭圆波导截面,在椭圆波导纵轮廓线函数中采用了相位重匹配方法,并利用粒子群算法进行了纵轮廓线优化,所设计的椭圆TE₀₁-TEs₁₁模式转换器在28 GHz时的转换效率为99.16%,在27～29.3 GHz模式变换器的效率大于90%,相对带宽为8.2%。所设计的TE₀₁-TEs₁₁椭圆模式转换器的转换段为现有长度的一半。将设计的椭圆模式转换器与两个过渡段相连,并在CST中进行仿真和验证,其结果与理论计算一致。设计出了一个中心频率点为28 GHz的高效、紧凑、高功率椭圆波导TE₀₁-TE₁₁模式转换器。     

多注速调管TM410 模同轴输出腔的研究

研究了多注速调管TM₄₁₀ 模同轴输出腔中出现的外观品质因数高,模式频率间隔小以及工作模式场分布的均匀性差等问题,提出了一种设置短路杆和金属环的输出腔结构,从而改善了TM₄₁₀ 模输出腔上述三个方面的性能。通过分析发现,适当设置短路杆和重入环不仅可以使外观品质因数降低,还可以改善工作模式的场分布;设置重入环还可以增大工作模式和邻近模式的频率间隔。利用CST-MWS 软件,对X 波段具有短路杆和金属环的多注速调管TM₄₁₀模同轴输出腔进行了模拟计算,其工作模式（TM₄₁₀模）的外观品质因数降低了42.7%（从540.4 降至309.6）,TM₄₁₀ 模与邻近模式的频率间隔均达到了1.3 GHz 以上,工作模式的场分布也变得均匀。     

Transmission characteristics of H 11 o multi-mode circular bend waveguide

Recently, the influences of high order mode E ₀₁ ^o and transimission characteristics of H ₁₁ ^o multimode circular bend waveguide used in a high performance Cassegrainian microwave antenna, which utilized an offset excited horn-feeder, for the antenna and feed system of 4,5 and 6 GHz bands have been studied and analyzed by N. Nakajima, et al. But in their paper, the influence and effective method of treatment for another important high order mode H ₂₁ ^o have not been solved. In this paper, higher order modes coupling characteristics in H ₁₁ ^o circular bend waveguide are analyzed according to the coupled wave equations and coupling coefficients of E ₀₁ ^o , H ₂₁ ^o modes and their amplitudes are computed. A broadband H ₂₁ ^o , E ₀₁ ^o mode filter has thereby been proposed. Experimental results indicated that it performs well in practical application. Thus, the problems still confronting N. Nakajima et al. are capable of being solved thoroughly. The 4 th Research Institute, Ministry of Posts and Communications     

TE11 modes in straight and curved circular waveguide with `deformed? cross-section

The two polarisations of TE11 modes are shown to be non-degenerated in a circular waveguide when its cross-section is `conveniently deformed?. So the crosspolar discrimination is improved in such a curved guide. This permits the use of this structure as an antenna feeder at frequencies about 12 GHz.     

UTD solution for electromagnetic scattering by a circular cylinderwith thin lossy coatings

A uniform geometrical theory of diffraction (UTD) solution is obtained for the field exterior to a two-dimensional circular cylinder with a thin lossy dielectric coating. The solution is convenient for engineering applications due to its simple ray format. In the lit region, the geometrical optics (GO) solution consists of the direct incident ray and the reflected ray. In the shadow region, the geometrical theory of diffraction (GTD) uses the creeping-wave format to calculate the diffracted field. In the transition regions adjacent to the shadow boundaries, where the pure ray optical solution fails, a `universal' transition integral is used for the UTD solution to calculate the field. Numerical values for the essential transition integral are deduced, by a heuristic approach, from alternative representations of the Green's function for a circular cylinder with coating. Numerical results obtained from the UTD solution show excellent agreement with the eigenfunction results for cylinders with thin dielectric coatings     

Matched windows in circular waveguide

Design curves are presented for the matching of a dielectric window in circular waveguide propagating the dominant TE₁₁ mode. The matching is accomplished by thick or thin inductive irises which are in contact with the window on both sides. This configuration gives wide bandwidth and is mechanically convenient, but requires consideration of coupling of the higher-order modes generated by the closely spaced discontinuities. Mode matching and the generalized scattering matrix are utilized     

LSA relaxation oscillations in a waveguide iris circuit

Large-signal computer simulations of GaAs LSA relaxation oscillations in an X-band waveguide iris circuit are presented. The study is focused on a particular oscillator and a realistic model of an experimental circuit is used. However, the results are typical for other LSA relaxation oscillators. Basic features of the microwave circuit, characteristic voltage and current waveshapes, frequency tuning with bias voltage, and oscillator starting transients are discussed. The RF output power is shown to build up in less than ten cycles. Circuit optimization for high dc to RF conversion efficiency is discussed and circuit data for nearly 30 percent efficiency are given. Finally, efficiency degradation is discussed when doping gradients are present, and effciencies of 15 and 10 percent appear possible for doping gradients as high as 20 and 60 percent, respectively. Hence, the LSA relaxation mode is shown to be less sensitive to doping gradients than the sinusoidal LSA mode.     

Design and analysis of iris-coupled and dielectric-loaded 1/8-cutTE01-mode microwave bandpass filters

The design and analysis of iris-coupled and dielectric-loaded 1/8-cut TE₀₁-mode filters is performed using globalized local solutions of Maxwell's equations as basis functions. It is found that this set of basis functions outperforms other edge-conditioned basis functions. To reduce the size of the filter and increase the Q factor of the resonators, dielectric rings with high dielectric constant are employed in the same design technique. The dimensions of the resonators are determined to accurately take into account the effect of coupling on their resonant frequencies, thereby reducing the need of tuning. Numerical results are compared with those obtained from the finite-element method (HP HFSS) and the mode-matching technique. Good agreement is demonstrated     

高斯激光束TEM00模散射信号模拟与分析

在广义Mie散射理论的基础上,研究了离轴球型粒子对TEM00基模高斯激光束的散射特性,依据高斯波束在球坐标系的展开形式,对展开系数的有限级数解形式进行了编程计算;模拟了高斯光束在离轴球型粒子散射的情况下,散射光强与粒径参数、折射率、散射角和散射粒子相对位置的关系;对模拟结果进行了讨论,并与平面波的散射规律进行了对比分析。结果显示:高斯光束的散射光强分布呈现出了与平面波散射不同的规律,但在大束腰半径条件下,与平面波的散射规律有许多共同之处。     

Radiation characteristics of a corrugated circular cylindricalwaveguide horn excited in the TE11 mode

The design and experimental studies on a corrugated circular cyclindrical waveguide antenna that is feed-excited in the TE₁₁ mode with suppressed far-out sidelobes are reported. To reduce the spillover in the region 90°⩽&thetas;⩽180°, an attempt was made to introduce circumferential corrugations on the outer surface of the waveguide wall. The design criterion used was that a minimum of 11 corrugations per wavelength were used, and in all there were 25 corrugations. The reason for selecting 25 corrugations was to ensure that the conduction currents induced on the outer walls of the guide were attenuated substantially and did not contribute to the far-out sidelobes. Measured E-plane and H-plane radiation patterns of the feeds and the corrugated waveguide are presented     

Evanescent modes in ferrite-filled circular waveguide

The analysis by Suhl and Walker (SW) is extended to include the evanescent state. The technique has applications in the field analysis of waveguide ferrite-dielectric interfaces.     

Study of the loss of the H 11 mode in a modified circular waveguide in a wide frequency range

The specific attenuation coefficient of the hybrid HE ₁₁ mode in a modified circular waveguide is calculated using a method developed earlier. Calculations are performed in a wide frequency range for a number of waveguide diameters. Combinations of the parameters of modified waveguides providing a substantial decrease in the specific attenuation as compared to that in an empty waveguide are determined.