Integrated Design of a Compact and Lightweight S-Band Traveling-Wave Tube Amplifier for a New Class of Microwave Power Module

Heather Song, Leslie Tekamp, Frank Francisco, Ming-Chieh Lin, Peter H. Stoltz, David Smith, Gil Wong Choi, Jin Joo Choi

Department of Electrical and Computer Engineering, University of Colorado, Colorado Springs, USA.
Department of Electrical and Computer Engineering, University of Colorado, Colorado Springs, USA;.
Department of Electronics Convergence Engineering, Kwangwoon University, Seoul, South Korea..
Samsung Thales Co., Yongin-Si, South Korea;.
Tech-X Co., Boulder, USA;.
Triton Services Inc., Breinigsville, USA;.

DOI: 10.4236/jemaa.2013.53016                

Abstract

A new class of compact and lightweight S-band 1 kW traveling-wave tube (TWT) is being developed for a microwave power module (MPM) that will be used for phased antenna array radar applications. The proposed S-band MPM provides a tenfold peak power increase compared to state-of-the-art S-band MPMs. In this paper, the design of the vacuum power booster TWT part of the MPM is presented. The compact and lightweight S-band TWT is driven by a 6 kV, 0.9 A electron beam. The amplifier is predicted by large-signal simulations to generate over 1 kW at S-band with 25 dB saturated gain and over 40% efficiency. The stability from unwanted oscillations has been investigated. To suppress the oscillations, the helix circuit has been coated with carbon composite material. The coaxial input and output antennas have been fabricated. For efficiency enhancement, a multi-stage depressed collector (MDC) has been designed using a 3D particle-in-cell (PIC) simulator, VORPAL. The collector design makes use of a current loop based on a feedback mechanism for effective design process. The integrated designs of a helix circuit, an electron gun, a periodic permanent magnet (PPM), antennas, and a collector are presented.

Keywords

TWT; MPM; Compact; Lightweight; Feedback Current Loop; Multi-Stage Collector

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	C. R. Smith, C. M. Armstrong and J. Duthie, “The Microwave Power Module: A Versatile RF Building Block for High-Power Transmitters,” Proceedings of the IEEE, Vol. 87, No. 5, 1999, pp. 717-737. doi:10.1109/5.757252
[2]	M. C. Smith, “Comparison of Solid State, MPM, and TWT Based Transmitters for Spaceborne Applications,” Proceedings of the IEEE Southeastcon, Orlando, 24-26 April 1998, pp. 256-259.
[3]	A. Katz, R. Gray and R. Dorval, “Performance of Microwave and Millimeter Wave Power Modules (MPMs) with Linearization,” Proceedings of the IEEE Military Communications Conference, Atlantic City, 17-20 October 2005, pp. 2693-2699. doi:10.1109/MILCOM.2005.1606073
[4]	R. J. Barker, J. H. Booske, N. C. Luhmann Jr. and G. S. Nusinovich, “Modern Microwave and Millimeter-Wave Power Electronics,” IEEE Press, Piscataway, 2005.
[5]	http://www.l-3com.com/
[6]	F. Francisco, “Private Communication,” 2009.
[7]	A. S. Gilmour Jr., “Principles of Traveling Wave Tubes,” Artech House, Norwood, 1994.
[8]	W. B. Herrmannsfeldt, “EGUN: An Electron Optics and Gun Design Program,” SLAC Report SLAC-331, Stanford, 1988.
[9]	J. R. M. Vaughan, “Synthesis of the Pierce Gun,” IEEE Transactions on Electron Devices, Vol. 28, No. 1, 1981, pp. 37-41. doi:10.1109/T-ED.1981.20279
[10]	M. Baird, “mPPM Program Manual User’s Guide,” 2002.
[11]	http://www.ansoft.com/products/em/maxwell/
[12]	C. Nieter and J. R. Cary, “VORPAL: A Versatile Plasma Simulation Code,” Journal of Computational Physics, Vol. 196, No. 2, 2004, pp. 448-473. doi:10.1016/j.jcp.2003.11.004