Analysis and Design of TE/sub 11/-to-HE/sub 11/ Corrugated Cylindrical Waveguide Mode Converters

A theoretical parametric study is given of a TE/sub 11/-to-HE/sub 11/ mode converter consisting of a section of cylindrical corrugated waveguide with varying slot depth. The analysis makes use of modal field-matching techniques to determine the scatter marks of the mode converter from which we deduce its propagation properties. It is shown that a mode converter consisting of only five slots achieves a return loss better than 30dB over the band 2.7相似文献   

A novel TEM-TE/sub 11/ mode converter

A novel mode converter that transforms coaxial transverse electromagnetic (TEM) mode to TE/sub 11/ circular waveguide mode is investigated. It is shown that with four metal plates inserted in the coaxial waveguide, the TEM mode will be converted to coaxial TE/sub 11/ mode, and finally, it forms a TE/sub 11/ conventional circular waveguide mode. The experimental test results are in good agreement with the computer simulations, which demonstrates the feasibility of the mode converter.     

X-band TM/sub 01/-TE/sub 11/ mode converter with short length for high power

A mode converter for X-band located between a generator and an antenna to convert TM/sub 01/ to TE/sub 11/ mode with high efficiency for a high power transmitting system is presented. The proposed mode converter has extended radius and excessive curvature with symmetric structure in order to convert between two modes efficiently with short length. The measured and simulated results of the return loss, mode patterns and efficiency of the proposed mode converter with 200 mm length are provided.     

High-performance circular TE/sub 01/-mode converter

This study presents the design and cold testing of a Ka-band TE/sub 01/-mode converter. A wave is efficiently converted from the TE/sub 10/ rectangular waveguide mode into the TE/sub 01/ circular waveguide mode. This converter comprises a power-dividing section and a mode-converting section. The field pattern and the working principle of each section are analyzed and discussed. A prototype was built and tested. Back-to-back transmission measurements exhibit excellent agreement to the results of computer simulations. The measured optimum transmissions are 97% with a 1-dB bandwidth of 5.8 GHz centered at 34.0 GHz. The angle-independent transmissions manifest high mode purity and the field pattern is directly demonstrated on a temperature-sensitive liquid-crystal sheet. In addition to exhibiting a high conversion efficiency, high mode purity, and broad bandwidth, this converter is also easy to construct and is structurally simple.     

H/sub o1/ Mode Circular Waveguide Components

A convenient method of launching the H/sub o1/ mode in round waveguide is described. Four resonant slots are employed in a compact end-feed transition design. Construction details and performance curves are given. Also described is a developmental bend which avoids the H/sub o1/-E/sub 11/ mode degeneracy problem by employing a superimposed pair of "E" and "H" plane rectangular waveguide bends. A mode absorber is described which is capable of reducing the mode impurities inherent in the transition design to a level of less than 0.1% of the emerging H/sub o1/ mode power. Other possible applications of the H/sub o1/ wave to problems other than low loss microwave transmission are briefly considered.     

Broadband linearly polarized beat-wave TEm1/TE11 mode converters

Broadband linearly polarized waveguide mode converters have been developed to transform the high-order cylindrical TE_m1 output wave from harmonic gyrotron amplifiers into the more useful TE₁₁ fundamental waveguide mode. The converter's corrugation period is equal to the beat between the two waves and the bandwidth is predicted to be inversely proportional to the number of periods. Four-period TE ₃₁/TE₁₁ and TE₄₁/TE₁₁ converters with an azimuthal perturbation of m_c=4 and m_c =5, respectively, have yielded a peak conversion efficiency of 98% with a bandwidth greater than 3% and a one-period beat-wave converter has been designed to yield 12% bandwidth. However, it has been observed in measurements that the strong coupling in a short converter can lead to a shift of the center-frequency with an accompanying reduction of the efficiency and bandwidth. A two-period TE₄₁/TE₁₁ converter with 5% bandwidth displayed a 5% frequency shift and a conversion efficiency of only 86%     

Ridge-Shaped Narrow Wall Directional Coupler Using TE/sub 10/, TE/sub 20/ , and TE/sub 30/ Modes

A new type of compact narrow wall directional coupler, whose coupling region is a ridge waveguide having dimensions such that TE/sub 10/, TE/sub 20/, and TE/sub 30/ modes can exist, is proposed and analyzed. Coupling ratio and nonreflecting condition are determined by the degree of interference between TE/sub 20/ and TE/sub 30/ modes, and between TE/sub 10/ and TE/sub 30/ modes, respectively. The coupler can be used as a variable power divider by varying the coupling slot height. For 3-dB coupling over the 16.0 to 19.0-GHz frequency range, power equality within /spl plusmn/0.5 dB, more than 30-dB isolation and more than 30-dB return loss can be obtained. Experimental coupling results have shown good agreement with the theory.     

圆波导TE01-TE11模式转换器设计与实现

基于耦合波理论的基础上,分析了TE01-TE11模式转换器的特性和半径渐变指数,讨论了中心轴线弯曲下的圆波导模式转换器,对中心频率33GHz的波导进行了模拟设计、仿真,在保证带宽的前提下,尽力降低转换器的长度和提高转换效率,最后达到了97．82％的转换效率,带宽达到2GHz。     

Circular TE/sub 0n/ Mode Filters for Guided Millimeter-Wave Transmission

A millimeter-wave circular TE/sub 01/ mode waveguide generates undesired circularly symmetric modes (TE/sub 02/, TE/sub 03/ modes, etc.) in bends or at discontinuities along a waveguide line. This paper describes the theory and experiment on the TE/sub 02/ and TE/sub 03/ mode filters developed for guided millimeter-wave transmission. The experimental results of two improved TE/sub 03/ mode filters show that the attenuation of the TE/sub 03/ mode is more than 16 dB for one type over the 40-70-GHz range. The TE/sub 01/-mode insertion loss of another type is about 0.2 dB over the 40-80-GHz range. The present mode filters can be applied to various high-speed guided rnillimeter-wave systems currently under development.     

Slot-Coupled T-junction of TE/sub 11/ Coaxial to TE/sub 10/ Rectangular Waveguide

A solution is presented to the problem of a slot-coupled T-junction of a TE/sub 11/ -mode coaxial to a TE/sub 10/ -mode rectangular waveguide. A variational technique is employed which combines the reaction concept with the field representation of a waveguide slot and leads to a closed-form solution for the junction scattering matrix. Numerical examples illustrate the characteristics of such a junction in practical applications. Good agreement between theory and experiment is obtained. Design criteria and examples are presented and discussed.     

A simple circular-to-rectangular waveguide transition

We describe a novel one-step TE/sub 11/-mode circular waveguide to TE/sub 10/-mode rectangular waveguide transition. The primary advantage of this device over existing transitions is its ease of fabrication. We have incorporated our transition into a number of waveguide components operating at V-band. The transition's measured return loss exceeds 15 dB over a 12% bandwidth centered near 60 GHz.     

Polarisation-insensitive Si/sub 3/N/sub 4/ strip-loaded BaTiO/sub 3/ thin-film waveguide with low propagation losses

A low-loss and polarisation-insensitive singlemode BaTiO/sub 3/ thin-film waveguide is reported. Polarisation-dependent loss as low as 0.1 dB/cm at a wavelength of 1.55 /spl mu/m has been achieved by a novel Si/sub 3/N/sub 4/ strip-loaded BaTiO/sub 3/ waveguide structure. Propagation loss of less than 0.9 dB/cm for both TE and TM polarisations was measured     

Attenuation and Radiation Characteristics of the HE /Sub 11/ - Mode

The asymptotic properties of the fundamental mode HE /sub 11/ inside a large waveguide of finite surface impedances are discussed. The analysis applies to corrugated waveguides, certain optical fibers and wave-guides with metal walls coated by a dielectric layer. It is shown that for k-->/spl infin/ the HE /sub 11/ mode has the following two properties: it is polarized in one direction and the field vanishes at the boundary. Because of these properties, it is useful in the design of microwave feeds, since it minimizes cross-polarization and edge illumination at the aperture. It is also useful for long distance communication because of its low attenuation constant. Both the far field of a feed and the attenuation constant are discussed. It is shown that rectangular apertures have negligible cross-polarization over wider bandwidth than circular apertures. Furthermore, if the medium inside a waveguide is Iossless, so that power is lost only at the boundary, then the attenuation constant is very small, it is asymptotic to (ka)/sup -2/ for large ka, where k= 2 pi/lambda and a is a characteristic dimension of the waveguide. A rectangular waveguide consisting of four metal plates coated with thin dielectric layers is shown to be attractive for long distance communication, because of its simplicity of fabrication and its low attenuation.     

TE/sub 01/ Mode Components in the 3-mm Region

In the 3-mm region (94 Gc) it is desirable to use waveguide components operating in the low loss TE/sub 01/ mode in circular waveguide rather than in fundamental-mode rectangular waveguide. Because this is a higher mode, mode purity is of major concern. A method of identifying undesired modes and their amplitudes is by means of radiation patterns from the end of the waveguide. Components developed to operate in this mode include a transition from rectangular to circular waveguide, standing wave detector, variable attenuator, directional coupler, flexible waveguide, fixed 90/spl deg/ bend and rotary joint.     

一种使用TE11为过渡模的TE01-HE11模式变换器设计

基于弯曲圆波导耦合理论和规则圆波导突变结构模式匹配法, 利用MATLAB软件编写的相关数值计算程序得到波导模式转换结构的优化参量, 最终使用CST软件对模型进行了仿真和验证.该系统主要由三部分组成: 一个TE01-TE01的过渡器, TE01-TE11和TE11-HE11的圆波导模式转换器.计算结果表明, 该TE01-HE11模式转换系统在24.13 GHz的频率有5%的带宽、转换效率超过了99%.计算结果、仿真结果和实物冷测结果是一致的.     

A Compact, Wide-Tuning Range, Dual TE/sub 111/ Mode Preselector

This paper describes the development of a dual TE/sub 111/ mode cavity preselector that is centrally loaded with a large, nonferrous, metallic perturbation plug. The cavity tunes over the 6 to 8 GHz range. Dual mode operation reduces the size of the cavity to one-half the size of a conventional cavity. The perturbing plug increases the separation between the desired TE/sub 111/ mode and the undesired, next higher TM/sub 011/ mode from 15 Percent to 33 Percent. The result is a 29 percent tuning range that is free from unwanted modes. The preselector exhibits a 3 dB bandwidth of 60 MHz, a 40 dB bandwidth of about 400 MHz, and an insertion loss that is no more than 1 dB.     

Leaky Waveguide: TE/sup cir//sub 01/ Circular Waveguide Periodic Array of Circular Apertures

This paper describes propagation characteristics of periodic leaky waveguides for helix waveguides and solid metal waveguides carrying a TE/sup cir//sub 01/ mode based primarily on experimental studies. For low-loss leaky waveguides, this type has not been considered feasible, because of the critical problem encountered in mode conversion-reconversion at the circular apertures. Additional loss due to the periodic array of the circular apertures and TE/sup cir//sub 01/ loss/frequency characteristics of the periodic leaky waveguide using helix waveguides and solid metal waveguides are measured by the shuffle-pulse method in the X-band. The periodic leaky waveguides using solid metal waveguides are seen to be acceptable for practical use as a low-loss leaky waveguide system, according to these measurements.     

A Novel TM$_01$–TE$_11$Circularly Polarized (CP) Mode Converter

A novel mode converter that converts a$hboxTM_01$mode to a CP$hboxTE_11$mode was developed. In the converter, the$hboxTM_01$mode is transformed into a coaxial transverse electric and magnetic (TEM) mode first, then the coaxial TEM mode is split in space into multiple$hboxTE_11$sector waveguide modes by eight plates in the coaxial waveguide, which further subject the$hboxTE_11$sector waveguide modes to different signal paths and hence effectively convert the TEM mode into a CP$hboxTE_11$mode. A mode converter at 4GHz was designed. The conversion efficiency of$hboxTM_01$-to-$hboxTE_11$is 99% at center frequency with an axial ratio of 0.7dB. Over the frequency range of 3.8–4.3GHz, the conversion efficiency exceeds 90%, and the axial ratio is less than 2.7dB. A good agreement between experiments and simulations was observed.     

Low-loss electrooptic BaTiO/sub 3/ thin film waveguide modulator

A strip-loaded electrooptic waveguide modulator based on an epitaxial BaTiO/sub 3/ thin film was fabricated and characterized for the first time. The strip-loaded waveguide structure greatly improves waveguide propagation and polarization-dependent loss performance. A propagation loss of 1.1 dB/cm and polarization dependent loss of 0.1 dB/cm were measured. The electrooptic waveguide modulator exhibited a half-wave voltage-interaction length product of 4.5 V /spl middot/ cm at a wavelength of 1542 nm. The measured effective electrooptic coefficient of the as-grown BaTiO/sub 3/ waveguide modulator was 38 pm/V. The experimental results indicate that a strip-loaded thin film waveguide modulator is suitable for photonic applications.     

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).