Second Harmonic Reduction of Traveling Wave Tube Amplifier Using Ferrite Material

Document Type: Research Paper

Authors

1 Malek Ashtar University of Technology

2 Professor of Electrical Engineering Department, Iran University if Science and Technology, Tehran, Iran.

Abstract

Traveling Wave Tubes (TWTs) consist of different elements. The most important element of TWT is the RF circuit. RF circuits in helix TWTs need a dielectric support to hold the helix; this support also has an effect in electromagnetic properties of RF circuits. A novel dielectric support is proposed to reduce the second harmonic of helix TWTs. The dielectric support in this structure consists of two sections. The first section consists of dielectric material as used in all TWT(s) supports, and the second one is a ferrite rod replaced in a portion of dielectric support. This configuration can act as a tunable band stop filter. The center frequency of the filter can be adjusted based on the second harmonic of the input frequency to reduce the second harmonic of TWT without any loss on fundamental amplified signal.

Keywords


[1]     F. Nekoogar, Ultra-Wideband Communications: Fundamentals and Applications. Upper Saddle River, NJ: Prentice Hall Press, 2005.

[2]     K. Siwiak and D. McKeown, Ultra-Wideband Radio Technology. Chichester, West Sussex: John Wiley & Sons, Ltd., 2004.

[3]     A. Grebennikov, RF and Microwave Power Amplifier Design. New York, NY: McGraw-Hill, 2005.

[4]     A.S.Gilmour, Jr. Principle of Traveling Wave Tubes, Magnetrons, Crossed-Field, Amplifiers, and Gyrotron, Boston, Artech House, 2011.

[5]     L. Hongtao, “Slow-wave characteristics of any shape spiral groove and has a central dielectric rod spiral groove,” M.S. thesis, School of Physical Electron., Univ. of Electron. Sci. and Tech., Sichuan, China, 2006.

[6]     M. K. Alaria, A. Bera, R. K. Sharma, and V. Srivastava, “Design and Development of Helix Slow-Wave Structure for Ku-Band TWT,” IEEE Trans. Plasma Science, vol. 39, no. 1, pp. 550-554, Jan. 2011.

[7]     F. He, J. Luo, M. Zhu, and W. Guo, “Theory, Simulations, and Experiments of the Dispersion and Interaction Impedance for the Double-Slot Coupled-Cavity Slow Wave Structure in TWT,” IEEE Trans. Electron Devices, vol. 60, no. 10, pp. 3576-3583, Oct. 2013.

[8]     A.S. Gilmour, Jr. Principle of Traveling Wave Tube, Boston London, Artech House, 1994.

[9]     A. Singh, J. E. Scharer, J. H. Booske, and J. G. Wohlbier, “Second- and third-order signal predistortion for nonlinear distortion suppression in a TWT,” IEEE Trans. Electron Devices, vol. 52, no. 5, pp. 709-717, May 2005.

[10]  Y. Hu, Y. Wang, Z. Yang, J. Li and B. Li, “Harmonic reduction for broadband helix TWTs with negative dispersion,” IVEC 2012, Monterey, CA, 2012, pp. 231-232.

[11]  T. K. Ghosh, A. J. Challis, A. Jacob, D. Bowler, and R. G. Carter, “Improvements in Performance of Broadband Helix Traveling-Wave Tubes,” IEEE Trans. Electron Devices, vol. 55, no. 2, pp. 668-673, Feb. 2008.

[12]  E. Gehrmann, P. Birtel, W. Dürr, and A. F. Jacob, “Filter Helix for Harmonic Suppression in Traveling Wave Tubes,” IEEE Trans. Electron Devices, vol. 61, no. 6, pp. 1859-1864, June 2014.

[13]  F. K. Mullen, “Traveling-wave tubes with ferrite attenuators,” IRE Trans. Electron Devices, vol. 8, no. 4, pp. 284-289, July 1961.

[14]  A. Karp and W. R. Ayers, “Design concepts for an octave-bandwidth coupled-cavity TWT,” International Electron Devices Meeting, 1978, vol. 24, pp. 546-549.

[15]  D. M. Pozar, Microwave Engineering, 2nd ed. New York: John Wiley & Sons, Inc., 1998.

[16]  (2011). CST User Manual. [Online]. Available: http://www.cst.com.