We report a MEMS (micro-electro-mechanical systems) compatible distributed loss type sever design for the 220 GHz double vane half period staggered traveling-wave tube amplifier (TWTA) [1]. The cold test simulations for a full TWT model including input/output couplers and broadband tapered vane transitions incorporating the sever, predicted a return loss (S11) of < -10 dB in the pass band (205 GHz-275 GHz) while an insertion loss/isolation (S21) of < ~-27 dB. The return loss of the TWT circuit did not degrade by the inclusion of the sever (< -10 dB) while still maintaining a good isolation (S21) for the RF signal. Particle-In-Cell (PIC) simulation analysis for the full 220 GHz TWT circuit (a) without sever and (b) with sever was conducted. With the inclusion of the sever, the TWTA showed generally a stabilized output response for all cases. The maximum power from the long sever case was ~25 W for Pin ~50 mW and the gain was ~27 dB. The reverse power was decreased to ~30 mW. For the short sever, the PIC results were even better with a maximum output power of ~62 W and a gain of ~30.92 dB with a reduced reverse power of ~5 mW for an input power of 50 mW at 220 GHz. The FFT spectrum of the RF signal at the output port also showed a spectrally pure waveform at 220 GHz.
2. Tonouchi, M., "Cutting-edge terahertz technology," Nat. Photon.,, Vol. 1, 97-105, 2007.
doi:10.1038/nphoton.2007.3
3. Appleby, R. and H. B. Wallace, "Standoff detection of weapons and contraband in the 100 GHz to 1 THz Region," IEEE Transactions on Antennas and Propagation, Vol. 55, 2944, 2007.
doi:10.1109/TAP.2007.908543
4. Booske, J. H., R. J. Dobbs, C. D. Joye, C. L. Kory, G. R. Neil, G.-S. Park, J. Park, and R. J. Temkin, "Vacuum electronic high power terahertz sources," IEEE Transactions on Terahertz Science and Technology, Vol. 1, 54-75, 2011.
doi:10.1109/TTHZ.2011.2151610
5. Barker, R. J., N. C. Luhmann, Jr., J. H. Booske, and G. S. Nusinovich, Modern Microwave and Millimeter-wave Power Electronics, IEEE/Wiley, 2005.
6. Gilmour, A. S., Principles of Traveling Wave Tubes, Artech House, Norwood, MA, 1994.
7. Sesahdri, R., S. Ghosh, A. Bhansiwal, S. Kamath, and P. K. Jain, "A simple analysis of helical slow-wave structure loaded by dielectric embedded metal segments for wideband traveling-wave tubes," Progress In Electromagnetics Research B, Vol. 20, 303-320, 2010.
doi:10.2528/PIERB10031201
8. Alaria, M. K., A. Bera, R. K. Sharma, and V. Srivastava, "Design and characterization of helix slow wave structure for Ku-band space TWT," Progress In Electromagnetics Research C, Vol. 16, 171-182, 2010.
doi:10.2528/PIERC10080602
9. Antonsen, T. M., P. Safier, D. P. Chernin, and B. Levush, "Stability of traveling-wave amplifiers with reflections," IEEE Transactions on Plasma Science, Vol. 30, 1089-1107, 2002.
doi:10.1109/TPS.2002.801563
10. Kumar, V., A. Vohra, and V. Srivastava, "Nickel and iron as attenuator materials for helix TWT," Indian Journal of Radio and Space Physics, Vol. 36, 345-347, 2007.
11. Dialetis, D., D. Chernin, T. M. Antonsen Jr., and B. Levush, "Accurate representation of attenuation in helix TWT simulation codes," IEEE Transactions on Electron Devices, Vol. 56, 935-944, 2009.
doi:10.1109/TED.2009.2015647
12. Baig, A., D. Gamzina, M. Johnson, C. W. Domier, A. Spear, L. R. Barnett, N. C. Luhmann, and Y.-M. Shin, "Experimental characterization of LIGA fabricated 0.22 THz TWT circuits," IEEE International Vacuum Electronics Conference (IVEC), 275-276, 2011.
doi:10.1109/IVEC.2011.5746982
13. Baig, A., J.-X. Wang, L. R. Barnett, N. C. Luhmann, and Y.-M. Shin, "Beam transport modeling of PPM focused THz sheet beam TWT circuit," IEEE International Vacuum Electronics Conference (IVEC), 351-352, 2011.
doi:10.1109/IVEC.2011.5747020
14. Shin, Y.-M., L. R. Barnett, and N. C. Luhmann, "Phase-shifted traveling-wave-tube circuit for ultrawideband high-power submillimeter-wave generation," IEEE Transactions on Electron Devices, Vol. 56, 706-712, 2009.
doi:10.1109/TED.2009.2015404
15. Baig, A., D. Gamzina, R. Barchfeld, C. Domier, L. R. Barnett, and N. C. Luhmann Jr., "0.22 THz wideband sheet electron beam traveling wave tube amplifier: Cold test measurements and beam wave interaction analysis," Physics of Plasmas, Vol. 19, 093110-8, 2012.
16., , http://www-siliconwafer.com/index.html.
17. Mavinakuli, P., S. Wei, Q. Wang, A. B. Karki, S. Dhage, Z. Wang, D. Young, and Z. Guo., "Polypyrrole/silicon carbide nanocomposites with tunable electrical conductivity," J. Phys. Chem. C., Vol. 114, 3874-3882, 2010.
doi:10.1021/jp911766y
18. Srivastava, V. and R. G. Carter, "Determination of sever positions in a coupled-cavity TWTs," IEE Proceedings H --- Microwaves, Antennas and Propagation, Vol. 138, 55-60, 1991.
doi:10.1049/ip-h-2.1991.0010
Submit
