High Frequency MEMS-based TWTS using Novel Interaction Circuits and Beam Sources

We propose to investigate innovative, wideband, traveling-wave tubes (TWTs) compatible with three-dimensional (3D) micro-electro-mechanical systems (MEMS) fabrication techniques for millimeter or sub-millimeter wave applications. At least three novelinteraction circuits designed around MEMS fabrication technology will be investigated, as well as a novel electron beam source using field emission array (FEA) technology, PPM focusing and depressed collector operation. The overall objective will be tointegrate several TWT components into the fabrication procedure to avoid conventional assembly and alignment procedures, which become increasingly difficult at higher frequencies. The batch nature of MEMS fabrication corresponds to repeatability ofcomponents resulting in increased yields and reliability, and reduced cost.During the Phase I effort, advanced, state of the art simulation tools will be used to thoroughly investigate each innovative interaction circuit for its thermal and electrical performance. In parallel, MEMS fabrication techniques will be explored for eachcircuit and the limitations on frequency and power will be established. Operation from Ka-band to THz frequencies will be considered. Based on the results, representative structures will be fabricated and characterized. In addition, all major tubecomponents will be designed, including a novel electron beam source using FEA technology, PPM focusing and depressed collector. Commercial and military satellites are spectrum challenged and are likely to be moving into the high frequency bands in the future. High-frequency devices with significant increase in yield, and reduction in the size and weight of the TWTA componentswould have major implications for defense and commercial products for radar and communications systems, particularly if there is an increase in reliability and flexibility. Size and weight constraints are often the driving factor in implementation inairborne systems used widely in the defense and aerospace industries. The impact on personal communications systems could also be quite large if the implementation costs are reduced. A typical commercial satellite employs on the order of 50-100 TWTA's;thus, the proposed weight and volume reductions would cause major savings to the satellite operator. In addition, by increasing the efficiency of the amplifiers on a communications satellite, it becomes possible to add additional channels withoutincreasing the capacity of the power system. The resulting increased communications capacity can be translated into increased revenue for the satellite operator that has an estimated value of $5M per percentage point of efficiency.The proposed product has great potential for dual (military as well as commercial) use. The probable military customers include US Navy for its Cooperative Engagement Capability (CEC) network for defending aircraft carrier battle groups against enemyaircraft and cruise missiles, Army for its EPLRS (Enhanced Position Location Reporting System), and Air Force for its Multi-sensor Command and Control Aircraft, or MC2A. It will integrate AWACS, Joint Stars, and Rivet Joint communications. The FY03 defensebudget includes $2.5 billion for programs involving communications in space. Domestic commercial customers will include BSS, Loral, Lockheed Martin, Orbital Sciences Corp., and Northrop Grumman Corp. (formerly TRW).