外文翻譯--基于過模波導(dǎo)的8毫米大功率te01-tm11模式轉(zhuǎn)換器（原文）

1、8mm High Power TE01—TM11 Mode Converter in Overmoded Waveguide Xu Le Center of Information Network, Sichuan Normal University, Chengdu 610066, China lelexu@sicnu.edu.cn. Niu Xin-jian Vacuum Electronics National Labo

2、ratory, College of Physical Electronics, UESTC, Chengdu 610054, China Abstract: Based on the mode coupling theory, design of TE01—TM11 mode converter geometry configuration with traditional waveguide axis constant cu

3、rvature and improved waveguide axis sinusoidal curvature is given for more acceptable geometry parameters. The conversion efficiency of 8mm high-power circular waveguide with waveguide axis sinusoidal curvature is ab

4、out 99% with bandwidth of 32%. Keywords: Bent waveguide; Mode conversion; Coupled wave equations; Phase rematch. Introduction The output mode of gyroklystron TE01 and TE02 are very inconvenient for direct use, so it

5、 must be taken a mode conversion, especially high power mode conversion. And its mode converter adopt mostly the following sequence[1]： 1. TE0n（gyrotron）—TE01—TE11—HE11（antenna） 2. TE0n（gyrotron）—TE01—TM11—HE11（antenna

6、） The first sequence has been employed here, adopting perturbation of axis curved, and arriving at an efficient circular waveguide converter with conversion efficiency reaching 98% and bandwidth exceeding 5%, while it

7、s overlength(881.6mm) confines its practice to a limited field with inconvenient machining. Thus the second sequence is chosen to for better usage, with TM11 as the intermediate polarized mode, HE11 the latter one, t

8、o radiate outside, during the process of which TE01—TM11 conversion is the most important. The same phase velocity of TE01 and TM11 made a proper selection of a part of the single-curvature circular waveguide fit the

9、 realization of their conversion well. Based on the sinusoidal curvature structure, creating a TE01 — TM11 mode converter of 8mm high-power circular waveguide with conversion efficiency coming to 99%, bandwidth exceedi

10、ng 32% and length being only 386mm, thus realizing an tighten, efficient mode converter of broad bandwidth. Fundamental equations The unevenness in a waveguide (the bent of axis in a circular waveguide, gradual radiu

11、s changes of the waveguide) will cause the energy coupling among different propagation modes and thus create mode conversion. The coupling wave equations based on the coupling wave theory are the fundamental equations

12、 which study axis curved circular waveguide mode converter[2]: [ ] ∑ ? ? ′ ′ + + ′ ′+ ′ ′ ′ ′+ ′ ′+ ?? =mn mn mn n m mn mn n mn m n m n mA C A C jA j dzdA) )(( ) )((γ(1) [ ] ∑ + ? ′ ′ ? + ′ ′? ′ ′ ′ ′? ′ ′+ +=mn mn mn n

13、 m mn mn n mn m n m n mA C A C jA j dzdA) )(( ) )((γ(2) where + mn Aand ? mn Aare the forward and backward wave complex amplitudes of the（mn）th mode. + ′ ′ ) )( ( mn n m Cand ? ′ ′ ) )(( mn n m Care the coupling coeff

14、icients between（mn）mode and （ n m ′ ′ ）mode whose direction of propagation are the same and opposite. Results of numerical calculation The geometry structure of TE01—TM11 mode converter with circular waveguide is a be

15、nt one. Owing to the same phase constant in the bent circular waveguide of mode TE01 and TM11, a proper bent waveguide can make them carry out continuous power coupling. Multimode factor, backward wave, ohmic consump

16、tion, axis curved and phase rematch etc, have been carefully considered in the calculation. When the incident mode TE01 is input the converter, it couples with TE11, TE12 and TM11 mode, spurious modes TE21 and TM21 c

17、arry the secondary coupling. According to the analysis on the coupling coefficients of these modes, other mode coupling can be out of consideration for their weak coupling and small output amplitude. Thus only TE01, T

18、E11, TE12, TM11, TE21 and TM21 are the focus here. Meanwhile, in order to lessen the ohmic consumption and enhance the bandwidth, converters must be as short as possible. Other coupling mode has been efficiently prev

19、ented by a proper change curvature of the waveguide, thus increasing the conversion efficiency. Two structures are employed: TE01—TM11 mode converter with constant curvature waveguide and with sinusoidal curvature wa

20、veguide. Sinusoidal curvature structure in equation (3) is accepted to reach high conversion efficiency with a shorter length and broader bandwidth through optimal 9781-4244-3501-2/09/$25.00 ©2009 IEEEcalculation,

21、 widened curvature range and strengthened input- output mode coupling. 332211 2 sin 2 sin 2 cos ) ( WzWzWz x y π ε π ε π ε ? ? =(3) Where, 1 ε , 2 ε , 3 ε are perturbation factor, 1 W , 2 W 3 W are related to beat wa

22、velength. Figure 1. Fractional power as a function of z along a 35GHz TE01-to-TM11 mode converter with a0=13.6mm and constant curvature. Figure 2. Fractional power as a function of z along a 35GHz TE01-to-TM11 mode

23、 converter with a0=13.6mm and optimum, sinusoidal curvature distribution. It is clear in Fig 1, 2, 3 that the output power of TE11 and TE21 can be efficiently reduced by the improved sinusoidal curvature waveguide,

24、making conversion efficiency increasing from 97% to 99% and the length being lessened much. 25 30 35 40 450.00.20.40.60.81.0Sinusoidal curvatureConstant curvatureConversion efficiencyz/dmFigure 3. Conversion efficien

25、cy versus frequency distribution For mode converters of single bent waveguide, the principles between circular waveguide radius, bent curvature, frequency and bandwidth are the same with double bent structure[3]. Und

26、er the same frequency, the shorter the waveguide radius and the length, the greater the mode conversion efficiency is obtained. Under the same circular waveguide radius, the greater the frequency, the longer the lengt

27、h and the smaller the bent curvature, bandwidth and mode conversion efficiency is obtained too. Conclusions Improving the sinusoidal curvature structure, and restrain others modes output power effectively, and increa

28、se mode conversion efficiency when the length of mode converter is greatly shorten. The conversion efficiency of 8mm high power circular waveguide TE01—TM11 mode converter is about 99% with bandwidth of 32%. Referenc

29、es 1. Thumm, M., “High-power millimeter-wave mode converters in overmoded circular waveguides using periodic wall perturbations,” Int. J. Electronics, vol.57, no. 6, 1225-1246. 2. Li, H., Thumm, M., “Mode coupling i

30、n corrugated waveguides with varying wall impedance diameter change,” Int. J. Electrons., vol.71, no.5, 827-844. 3. Niu Xin-jian, Yu Sheng, Li Hong-fu, et al. Design for Overmoded Bent Circular Waveguide Mode Couplin

31、g. Journal of Infrared and Millimeter Waves, 2006, 25 (1): 67-70. 0 1 2 3 4 5 6 70.00.20.40.60.81.0TE01TM11PsumFractional powerz/dm0 1 2 3 4 5 6 70.0000.0040.0080.0120.016TE12TM21TE21TE11Fractional powerz/dm0.0 0.5 1.0