共查询到20条相似文献,搜索用时 312 毫秒
1.
M. Sumathy K. J. Vinoy S. K. Datta 《Journal of Infrared, Millimeter and Terahertz Waves》2009,30(3):294-301
An analysis of rectangular folded-waveguide slow-wave structure was developed using conformal mapping technique through Schwarz’s
polygon transformation and closed form expressions for the lumped capacitance and inductance per period of the slow-wave structure
were derived in terms of the physical dimensions of the structure, incorporating the effects of the beam hole in the lumped
parameters. The lumped parameters were subsequently interpreted for obtaining the dispersion and interaction impedance characteristics
of the structure. The analysis was benchmarked for two typical millimeter-wave structures, one operating in Ka-band and the
other operating in Q-band, against measurement and 3D electromagnetic modeling using MAFIA. 相似文献
2.
M. Sumathy K.J. Vinoy Subrata Kumar Datta 《AEUE-International Journal of Electronics and Communications》2010,64(12):1192-1195
A simple yet accurate equivalent circuit model was developed for the analysis of slow-wave properties (dispersion and interaction impedance characteristics) of a rectangular folded-waveguide slow-wave structure. Present formulation includes the effects of the presence of beam-hole in the circuit, which were ignored in existing approaches. The analysis was benchmarked against measurement as well as with 3D electromagnetic modeling using MAFIA for two typical slow-wave structures operating in Ka- and Q-bands, and close agreements were observed. The analysis was extended for demonstrating the effect of the variation of beam-hole radius on the RF interaction efficiency of the device. 相似文献
3.
Mukesh Kumar Alaria A. Bera A. K. Sinha V. Srivastava 《Journal of Infrared, Millimeter and Terahertz Waves》2009,30(3):211-216
This paper describes the analysis of helix slow-wave structure (SWS) for a high efficiency space traveling wave tube that
is carried out using Ansoft HFSS and CST microwave studio, which is a 3D electromagnetic field simulators. Two approaches
of simulating the dispersion and impedance characteristics of the helix slow wave structure have been discussed and compared
with measured results. The dispersion characteristic gives the information about axial propagation constant (Beta). Which
in turn yields the phase velocity at a particular frequency. The dispersion and impedance characteristics can be used in finding
the pertinent design parameters of the helix slow-wave structure. Therefore a new trend has been initiated at CEERI to use
Ansoft HFSS code to analysis of the helix slow wave structure in its real environment. The analysis of the helix SWS for Ku-band
140W space TWT has been carried out and compared with experimental results, and found is close agreement. 相似文献
4.
Jin Xu Wenxiang Wang Yubin Gong 《Journal of Infrared, Millimeter and Terahertz Waves》2005,26(9):1355-1368
The slow-wave characteristics taking no account of space harmonics for periodically iris-loaded elliptical waveguides is presented. By using the field-matching method, the dispersion equation and the mean interaction impedance for odd and even hybrid modes of this structure are derived respectively. It is indicated from the numerical calculation results that changing the eccentricity can improve the dispersion characteristics and the interaction impedance for oHEM01 mode. 相似文献
5.
G. Singh S. M. S. Ravi Chandra P. V. Bhaskar P. K. Jain B. N. Basu 《International Journal of Electronics》2013,100(12):1463-1479
A cylindrical waveguide, provided with wedge-shaped metal vanes projecting radially inward from the wall of the guide, excited in the transverse electric (TE) mode, was analysed. The analysis was carried out considering the angular harmonics generated by the angular positioning of the vanes. A set of equations was generated in the Fourier amplitudes of field constants. The condition for nontrivial solutions for the field constants gave the dispersion relation of the structure. From the expression of power flow down the structure, its interaction impedance was also estimated. The shape of the dispersion characteristics and the value of the cutoff frequency as well as the interaction impedance characteristics of the waveguide were found to depend on the vane parameters their number as well as their radial and angular dimensions. The optimum vane parameters were obtained corresponding to the minimum variation of the slope of the ω-β dispersion plot, such parameters being useful from the standpoint of the bandwidth of a gyro-travelling-wave tube (gyro-TWT) using a vane-loaded cylindrical waveguide as the interaction structure. The dispersion and impedance characteristics, which were found typically for the TE01 mode as defined for the structure, taking four vanes, were more sensitive to the number and angular width of the vanes than to their radial depth. The value of the interaction impedance, calculated at the potential beam position, was found to be higher for a loaded waveguide than for an unloaded one, and it depended on the frequency of operation relative to the cutoff. The interaction impedance also depended on the position of the beam relative to the waveguide wall where it was estimated, and hence the optimum beam position corresponding to the maximum interaction impedance was found. The theory was validated against the dispersion characteristics reported elsewhere typically for four-vane magnetron-like structures excited in the 2π mode. Although the present study was restricted to ‘cold’ analysis of the structure in the absence of the electron beam, it could provide important feedback for analysing a gyro-TWT, using a vane-loaded cylindrical waveguide, and hence for predicting the structure parameters for the wide-band performance of the device. 相似文献
6.
《Electron Devices, IEEE Transactions on》1970,17(4):383-384
A slow-wave structure intended for use in solid-state traveling-wave amplifiers is described. The structure is a meander line with adjacent conducting elements electrically connected by lumped capacitors. The dispersion curve is derived and shown to agree with experiment. The structure is found to have a passband which is dependent on the coupling capacitors. The interaction impedance is estimated. 相似文献
7.
提出了一种开敞式脊加载折叠波导慢波结构.通过除去直波导段周围的金属边界,形成一种开敞式结构以减弱色散,同时在直波导段加脊以提高耦合阻抗.研究表明,和传统结构相比,新型结构在不影响带宽的前提下,有效提高了耦合阻抗,尤其在大功率设计情况下,耦合阻抗的提高接近1倍. 相似文献
8.
从行波管工作的物理特性提出了一种获得折叠波导慢波结构参数的简单方法,给定工作频率和电压,能够获得折叠波导慢波结构的初始参数.设计了D波段的折叠波导结构来验证该方法,对其冷测特性如色散、耦合阻抗进行了分析.仿真结果表明,设计的折叠波导慢波结构在中心频率处具有较平缓的色散关系,在中心频率处耦合阻抗为3.5欧姆.在电子注电压为20.6 kV,电流为15 mA时,27 mm(50个周期)的折叠波导慢波结构在220 GHz具有13.5 dB的增益,3 dB带宽为11 GHz(213~224 GHz).同时讨论了折叠波导慢波结构的微加工工艺,并通过UV-LIGA工艺获得了实验样品. 相似文献
9.
Chengfang Fu Bo Zhao Yudong Yang Yongfeng Ju Dingli Yang Bo Chang Xiaofeng He 《Journal of Infrared, Millimeter and Terahertz Waves》2016,37(11):1106-1116
A simple equivalent circuit analysis of the frame–rod slow-wave structure (SWS) on dielectric substrates of a traveling-wave tube (TWT) is developed, using the quasi-TEM approximation approach for the dispersion and coupling impedance characteristics of the structure. Moreover, the obtained complex dispersion equation and coupling impedance are numerically calculated. The calculation results by our theory method agree well with the results obtained by the 3D EM simulation software HFSS. It is shown that the dispersion of the frame–rod circuit is decreased; the phase velocity is reduced and the bandwidth becomes greater, while the coupling impedance decreases after filling the dielectric materials in the frame–rod SWS. In addition, a comparison of slow-wave characteristics of this structure with a rectangular helix counterpart is made. As a planar slow-wave structure, this structure has potential applications in compact TWTs based on the micro-fabrication technology, which could be scaled to millimeter wave, even to THz frequency. 相似文献
10.
Characterized with full-metal structure, high output power and broad bandwidth, microfabricated folded waveguide is considered
as a robust slow-wave structure for millimeter wave traveling-wave tubes. In this paper, cold-test (without considering the
real electron beam) properties were studied and optimized by 3D simulation on slow-wave structure, for designing a 220 GHz
folded waveguide traveling-wave tube. The parametric analysis on cold-test properties, i.e., phase velocity, beam-wave interaction
impedance and cold circuit attenuation, were conducted in half-period circuit with high frequency structure simulator, assisted
by analytical model and equivalent circuit model. Through detailed parametric analyses, interference between specified structural
parameters is found on determining beam-wave interaction impedance. A discretized matrix optimization for interaction impedance
was effectively carried out to overcome the interference. A range of structural parameters with optimized interaction impedance
distributions were obtained. Based on the optimized results, a broadband folded waveguide with cold pass-band of about 80 GHz,
flat phase velocity dispersion and fairly high interaction impedance was designed for a 220 GHz central frequency traveling-wave
tube. A three-dB bandwidth of 20.5 GHz and a maximum gain of 21.2 dB were predicted by small signal analysis for a 28 mm-long
lossy circuit. 相似文献
11.
S. K. Datta E. V. Jayashree S. D. Veena Lalit Kumar 《Journal of Infrared, Millimeter and Terahertz Waves》2007,28(9):779-787
A novel technique of broadbanding a helical slow-wave structure through negative dispersion shaping is proposed. The model considers a simple continuous chiral dielectric support for the helix inside a metallic barrel, unlike conventional helix slow-wave structures with three discrete dielectric supports at 1200 apart. The dispersion relation of the slow-wave structure was derived following sheath-helix abstraction, suitably benchmarked for special cases, and was used for analyzing the dispersion behavior of a typical slow-wave structure. Chiral dielectric loading could easily provide negative dispersion characteristics (required for broadband operation) by merely controlling the chirality parameter alone. The scheme with its simple geometric configuration is expected to be useful for millimeter-wave devices providing better thermal management. 相似文献
12.
Jianhong Yang Yong Zhang Xueyuan Cai Lin Li 《Journal of Infrared, Millimeter and Terahertz Waves》2009,30(6):611-621
The effects of different metallic vane-loaded helix slow-wave structures of a traveling-wave tube are proposed based on the
analysis of the Fourier expansions of the exterior region with metallic vanes. The influences of the metallic vanes dimensions
on the phase velocity and interaction impedance are considered in detail. The computed data is compared with the reference
data in the 0−16 GHz frequency range with a good consistency. The analytical results reveal that the method of using Fourier
expansions can contribute effectively to the reducing of the error between the theoretical and experimented data (around 1.2%).
By analyzing the computed results, the performances of the helix slow-wave structure, with T-shaped metallic vanes are superior
to the sector-shaped with the same designed parameters. Adjustments can be made to the outer radius of T-shaped metallic vanes
which then control the dispersion relation showing either negative or positive, and it is similar to sector-shaped vanes by
adjusting its inner radius. And with increasing the distance between the helix and metallic vanes, the dispersion characteristics
and interaction impedance of the helix slow-wave structure with T-shaped/sector-shaped metallic vane are all improved. 相似文献
13.
Zhigang Lu Yubin Gong Yanyu Wei Wenxiang Wang 《Journal of Infrared, Millimeter and Terahertz Waves》2006,27(8):1095-1108
A new type of partial-dielectric-loaded rectangular waveguide grating slow-wave structure (SWS) for millimeter wave traveling wave tube (TWT) is presented in this paper. The radio-frequency characteristics including the dispersion properties, the longitudinal electric field distribution and the beam-wave coupling impedance of this structure are analyzed. The results show that the dispersion of the rectangular waveguide grating circuit is weakened, the phase velocity is reduced and the position of the maximum E z is basically invariant after partially filling the dielectric materials in the rectangular waveguide grating SWS. Although the coupling impedance decreases a little, it still keeps above 40 Ω. 相似文献
14.
An improved version of split-folded waveguide slow-wave structure for crossed-field tubes is described. The equivalent capacitance type analysis is given that predicts the dispersion characteristics of the structure accurately. The experimental slow-wave structure demonstrates a usable band from 1·4 to 3·1 Gc (bandwidth 2·25 : 1), The interaction impedance of the modified structure being reasonably largo, allows the use of fundamental backward or first forward-wave harmonics over wide bandwidths. 相似文献
15.
Murugan Sumathy Subrata Kumar Datta 《Journal of Infrared, Millimeter and Terahertz Waves》2017,38(5):538-547
A single-section slow-wave structure for a W-band folded-waveguide traveling-wave tube with operating bandwidth of around 4% was designed for delivering the output power of 50 W at the operating voltage of 13.5 kV and operating beam current of 80 mA. The design was carried out using analytical formulations and 3D electromagnetic simulations. The beam-wave interaction analysis was carried out using large signal Lagrangian analysis and particle-in-cell simulation. The folded-waveguide slow-wave structure along with input-output couplers and RF windows were fabricated. Cold test measurements were carried out for dispersion characteristics of the slow-wave structure and voltage standing-wave ratio and insertion loss characteristics of the RF window. The measured cold circuit parameters show close agreement with the analysis. 相似文献
16.
The slow-wave characteristics taking account of space harmonics for confocal corrugated elliptical waveguides are presented. By using the field-matching method, the dispersion equation, and the mean interaction impedance for odd hybrid modes of this structure are derived. Based on our results, changing the waveguide eccentricity can improve the dispersion characteristics and the interaction impedance for oEH01 mode 相似文献
17.
本文选用矩形耦合腔作为太赫兹扩展互作用振荡器(EIO)的慢波结构,鉴于其结构的复杂性,采用等效电路方法计算其色散.详细研究了腔体和耦合槽的电路参数,计算了不同结构尺寸、圆形和矩形电子通道的0.12THz和0.225THz慢波结构的色散特性.并采用专业电磁软件,研究了不同结构参数下的色散特性、耦合阻抗和特征阻抗.通过对色... 相似文献
18.
本文采用矩形波导加载光栅的慢波结构作为太赫兹返波管的高频结构,通过理论分析和电磁仿真研究了该慢波结构的色散特性和互作用阻抗,理论分析结果和仿真结果能很好地吻合。在理论分析的基础上,设计了一个中心频率为340GHz的返波管,经粒子模拟软件计算,在较低电流密度的情况下该返波管输出功率达100mW且可调带宽约30GHz。 相似文献
19.
S. V. Mukhin D. Yu. Nikonov V. A. Solntsev 《Journal of Communications Technology and Electronics》2008,53(10):1250-1258
The properties of the local coupling impedance that determines the efficiency of the electron-wave interaction in periodic slow-wave structures are investigated. This impedance is determined (i) through the characteristics of the electromagnetic field in a slow-wave structure and (ii) through the parameters of a two-port chain simulating the structure. The continuous behavior of the local coupling impedance in the passbands of slow-wave structures, at the boundaries of the passbands, and beyond the passbands is confirmed with the help of a waveguide-resonator model. 相似文献