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1.
The design method of mode selective directional couplers from a transverse electric mode in a circular waveguide to the fundamental mode in a rectangular wave guide is presented in this paper. The design results for a TE01 circular mode coupler intended for use in the output power measurement of a high power gyroklystron are reported; these results indicate that more than 50-80dB directivity and sufficient suppression of unwanted modes can be obtained with a coupler less than 07m in length. The effects of frequency and rectangular wave guide size on coupler parameters are also discussed in this paper 相似文献
2.
W. LAWSON M. E. READ W. X. WANG M. NAIMAN 《International Journal of Electronics》2013,100(5-6):1135-1144
The formalism for analysing weakly coupled, aperture-type, mode-selective directional couplers is applied to the geometry of an end-fire high power gyrotron. A design procedure based on the constraints of a highly overmoded circular waveguide is presented. Several designs for a — 60dB, 9.85GHz, TE01 coupler are evaluated. Measurements of the forward and reverse coupling for the principal mode are found to be in good agreement with theory. 相似文献
3.
设计了一种结构紧凑、工作频带较宽、耦合平稳、高方向性的十字形多孔耦合的太赫兹波导定向耦合器。基于多孔耦合原理,利用HFSS软件对太赫兹波导定向耦合器进行了模型仿真和结构优化。仿真结果表明:在325~475 GHz带宽范围内,该多孔耦合太赫兹波导定向耦合器耦合度达到7.50.8 dB,隔离度达到30 dB,即方向性优于20 dB,各端口回波损耗小于-20 dB。通过对该波导定向耦合器进行高温高压模拟仿真,确定了使用负性光刻胶SU-8作为结构材料的可行性,提出应用MEMS工艺在硅衬底上进行加工,将牺牲层工艺应用到波导腔结构的制作中。利用光刻在直通波导和耦合波导公共宽壁上形成的十字形等间距排列耦合孔结构,可以实现较宽的带宽和良好的耦合平坦度。该方法提高了耦合孔尺寸和位置的精度,减小了反射损耗,为太赫兹波导结构的加工提供了新思路。 相似文献
4.
C. DEL RĺO J. M. NET J. PADULLÉS T. SANCHO M. SOROLLA M. THUMM 《International Journal of Electronics》2013,100(6):1101-1111
A new method to study rippled-wall mode converters based on a generalized investigation of multi-resonance phenomena in periodically perturbated circular oversized waveguides is presented. These resonances cause serious problems in the design of advanced, very high-power millimetre wave mode converters. The concept of a mode diagram helps in the initial design steps to get a global feel for possible resonances at each frequency and waveguide diameter. The optimal conversion path is determined from this mode diagram to avoid unwanted mode resonances. This method is shown applied to a TE0.1?TE03converter with a waveguide diameter of 27-79mm working at 60GHz. This converter is very close to the worst resonance effect (first-order resonance: |β03? β04.| ≈| β03? β01 |) which destroys totally the desired conversion effect. The second example shown is a TE02?TE01 converter with a waveguide diameter of 44-45 mm working at 28 GHz. In this case the resonance effect is of second order (i.e. | β02? β03|≈2| β01? β02|). 相似文献
5.
A low loss, high directivity dual directional coupler has been developed suitable for fabrication in waveguide bands up to WR3 (220-325 GHz). The design uses waveguide split on the E plane centerline with three waveguides running side by side and coupling holes made by drilling through all three guides. Construction is relatively simple and the resulting structure is very robust mechanically. Typical coupling is 15 dB, directivity is 25-30 dB, and the insertion loss of the WR3 coupler is 0.5 dB 相似文献
6.
《Microwave Theory and Techniques》1971,19(9):781-783
A coaxial directional coupler has been developed which allows adjustment of the length of the coupling slot to /spl lambda//4 or 3/spl lambda//4 throughout the frequency range 0.3 to 8.5 GHz. Coupling is flat to within 0.05 dB from 0.3 to 3 GHz (/spl lambda//4 mode) and 0.1 dB from 0.9 to 8.5 GHz (3/spl lambda//4 mode). The coupler has 50-dB coupling, 30- to 40dB directivity and was designed primarily for high power measurement (1 to 1000 W) using a low-power meter on the sidearm. The VSWR for the two modes of operation is 1.02 to 1.05. Five octave bandwidth-type couplers would be required to cover this same frequency range. 相似文献
7.
Hui Wang Hongfu Li Yong Luo Ran Yan 《Journal of Infrared, Millimeter and Terahertz Waves》2011,32(2):172-185
The stability analysis of a Ka-band gyrotron traveling-wave tube amplifier (gyro-TWT) operating in the circular TE01 mode at the fundamental cyclotron harmonic is presented. The small signal linear theory is used to analyze the amplification
of operation mode and oscillation of parasitic modes. The optimum dielectric parameters including loss layer thickness and
permittivity are given. Propagation loss of operation mode is 3 dB/cm with the thickness of loss layer d = 0.7 mm and relative
permittivity ξ″ = 11−6j, and propagation loss per unit length of parasitic modes TE11, TE21, TE02 at each oscillation frequency (24.85 GHz, 27.85 GHz, 61.2 GHz) is 2.5 dB/cm, 6 dB/cm, 7.5 dB/cm, respectively, sufficient
to suppress oscillations of operation and parasitic modes. Taking advantage of the optimized parameters of loaded dielectric,
a high gain scheme has been demonstrated in a 34-GHz, TE01-mode gyro-TWT, producing 160 kW saturated output power at 40 dB stable gain and 22.8% efficiency with a 3-dB bandwidth of
5%. 相似文献
8.
The performance of multihole directional couplers can be considerably improved by placing a second hole structure to the existing one. The improvement may be aimed at directivity or at suppression of certain unwanted modes propagating either in forward or backward direction. 相似文献
9.
描述了一种微带功分耦合器,它是收发(T/R)组件中的重要组成部分,起着监测和校准的作用.项目设计要求的工作频段在9.3GHz~9.8GHz,端口驻波应小于1.2,两臂间隔离度大于25dB,两个定向耦合器的耦合度C=30dB,定向性D=15dB~20dB.常规微带耦合器的定向性比带状线耦合器的定向性差,有多种方法可以改善... 相似文献
10.
Demonstration of a High-Order Mode Input Coupler for a 220-GHz Confocal Gyrotron Traveling Wave Tube
Xiaotong Guan Wenjie Fu Yang Yan 《Journal of Infrared, Millimeter and Terahertz Waves》2018,39(2):183-194
A design of high-order mode input coupler for 220-GHz confocal gyrotron travelling wave tube is proposed, simulated, and demonstrated by experimental tests. This input coupler is designed to excite confocal TE 06 mode from rectangle waveguide TE 10 mode over a broadband frequency range. Simulation results predict that the optimized conversion loss is about 2.72 dB with a mode purity excess of 99%. Considering of the gyrotron interaction theory, an effective bandwidth of 5 GHz is obtained, in which the beam-wave coupling efficiency is higher than half of maximum. The field pattern under low power demonstrates that TE 06 mode is successfully excited in confocal waveguide at 220 GHz. Cold test results from the vector network analyzer perform good agreements with simulation results. Both simulation and experimental results illustrate that the reflection at input port S11 is sensitive to the perpendicular separation of two mirrors. It provides an engineering possibility for estimating the assembly precision. 相似文献
11.
We design a single-ridged coaxial hybrid coupler which excites a TE011 mode of high mode content in a cylindrical cavity, resonating at 28.2GHz. The coupler consists of a WR-28 rectangular waveguide, a coaxial TEn11 cavity, and a cylindrical TE011 cavity. Both TE311 coaxial cavity and TE411 single-ridged coaxial cavity are analyzed to examine the TE011 mode purity in the central cavity. Mode purity analysis is performed by a field expansion method using Fourier-Bessel orthonormal basis functions. Numerical calculations predict that the TE411 single-ridged coaxial cavity excites the TE011 mode with mode purity of 98.6%, which is improved by 3% higher compared with the TE311 coaxial cavity. Measurements on the single-ridged coaxial coupler show a resonant frequency at 28.078GHz and ohmic and external Qs of 1560, 473 respectively, which are in good agreement with the simulated results of a 3-D finite element electromagnetic code. 相似文献
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13.
为解决弱耦合时微带平行耦合线定向耦合器方向性低的问题,提出了适用于大功率场合的小型化高方向性微带双定向耦合器。基于传统四分之一波长平行耦合三线微带双定向耦合器结构,采用扇形微带电容加载可明显减小耦合器尺寸并增大隔离度,通过耦合边缘引入锯齿结构进一步提高了方向性。负载电阻采用扇形微带短截线接地设计,避免电气化过孔,使得加工更加简单。设计了一个中心频率为915 MHz、耦合度为20 dB 的微带双定向耦合器,利用HFSS 仿真软件对耦合器结构进行优化设计,并做了实物加工和测试。实测结果表明,在中心频率处耦合度为20.2 dB,方向性达到32.1 dB;在0.74~1.35 GHz 频带内,输入匹配良好,耦合度波动小于0.5 dB,方向性高于20 dB。 相似文献
14.
The directivity versus frequency of a multihole waveguide coupler may be expressed as a polynomial whose complex roots, if placed off the unit circle, provide the opportunity of a rippled response. Two designs using seven equispaced holes, one each with 3.0 and 0.5 dB ripple, were implemented at X -band, and experimental validation of the theory has been excellent 相似文献
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16.
Wide-band directional couplers using П-Shape dielectric waveguide in the parallel coupling region are investigated in detail
by a rigorous mode matching method, both the eigenvalue problem of the coupled П-guide and the coupling characteristics of
curved transition structure are solved accurately. Particular attention is directed toward the effects of transition waveguides
on the scattering and coupling performance of the coupler to give useful guidelines for the design and optimization consideration.
Finally, a 3-dB directional coupler is proposed with quite constant coupling factor (within ±0.5dB) throughout a wide frequency
band from 34 GHz to 40 GHz. 相似文献
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18.
《Microwave Theory and Techniques》1968,16(12):995-1006
A precise method of analysis of multiaperture waveguide directional couplers has been developed and used to investigate the performance of couplers designed both by conventional theories and by a new synthesis technique. The analysis is based on the equivalent four-port network of the coupler, the apertures being represented by lumped reactances in series and/or shunt with dispersive transmission lines, representing the waveguides. The effects of finite aperture dimensions and common wall thickness are taken into account. Many couplers designed on the usual basis of a first-order loose-coupling approximation have good directivity, even for tight (3 dB) coupling, but previous theories do not give the predicted directivity and are often far from optimum in design. A new synthesis technique based on the distributed low-pass prototype filter has been devised, and shown to give results close to the predicted performance. It has led to the construction of compact multiaperture directional couplers having directivity greater than 43 dB over complete waveguide operating bands. 相似文献
19.
This paper proposes a new design of directional couplers with high directivity for personal communication services (PCS) and International Mobile Telecommunications‐2000 (IMT‐2000). The directional coupler is used to check and verify the power, frequency, and antenna reflection of a signal at transmission stations for mobile communications. The performance requirements of directional couplers are a strong coupling to reduce the effect on the transmitted power and high directivity to suppress the interference of the reflected signals and reduce the errors in communication. So far, various architectures have been proposed to gain high directivity, and there have been many studies used to obtain a strong coupling. However, conventional architectures for high directivity and strong coupling have a directivity of only about 20 dB, and there have been difficulties to achieve the higher directivity of 30 dB suitable for PCS and IMT‐2000. This paper proposes a new architecture of directional couplers based on a grounding composed of strip lines, and compares the test results of this directional coupler with conventional ones. The results show that the proposed directional coupler has a directivity of more than 30 dB and is adequate for PCS and IMT‐2000. 相似文献
20.
《Microwave and Wireless Components Letters, IEEE》2009,19(6):362-364