SITIS Archives - Topic Details
Program:  SBIR
Topic Num:  AF071-228 (AirForce)
Title:  Plasma Sheath-Tolerant Radio Frequency (RF) Systems on Hypersonic Air Vehicles
Research & Technical Areas:  Air Platform, Sensors, Electronics

 The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), which controls the export and import of defense-related material and services. Offerors must disclose any proposed use of foreign nationals, their country of origin, and what tasks each would accomplish in the statement of work in accordance with section 3.5.b.(7) of the solicitation.
  STATEMENT OF INTENT: Develop plasma sheath measuring instruments, an extremely high priority for this PEO
  Objective:  Develop innovative instrumentation for hypersonic air vehicles to characterize the hypersonic plasma sheath, measure antenna performance parameters, and enable RF systems to perform in spite of plasma
  Description:  Air vehicles flying at hypersonic speeds are expected to take on a growing role in future air operations. These vehicles will need reliable RF systems to perform communication, navigation, reconnaissance, targeting, and terminal guidance. High temperature flow and the resulting airframe heating create a plasma sheath that alters the phase and amplitude of radio signals transmitted and received by the vehicles and often blacks them out altogether. Blackout affects all military and civilian reentry vehicles, including the Space Shuttle, and prevents them from receiving communication and global positioning system (GPS) signals. Even in the case that the signals are not entirely blacked out—as might be the case for X-band radar—the sheath remains a lossy, dispersive, inhomogeneous, and fluctuating medium. These characteristics pose a significant challenge for wideband RF systems using conformal arrays for communication, radar, or GPS reception. Such a system must contend with spatially and temporally varying antenna matching characteristics. Several hypersonic flight test opportunities are planned for the FY08 to FY12 period, leading to future operational hypersonic air vehicles. Modern RF instrumentation must be developed to fly on these vehicles and measure antenna matching and mutual coupling characteristics, as well as plasma sheath thickness and density. Frequencies of interest include those used for communication (ultrahigh frequency, UHF), telemetry (S-band), radar (C- and X-band) and GPS (L-band). The instrument must be capable of miniaturization and easy, conformal integration with the flight vehicle thermal protection system. The instrument will ultimately enable conformal antenna arrays covered by a plasma sheath to be adaptively optimized in flight, allowing the RF systems to be employed effectively in spite of the plasma sheath.

  PHASE I: Develop innovative RF instrumentation to measure antenna performance and plasma parameters during hypersonic flight, using state-of-the-art technology capable of miniaturization and integration with flight vehicles. Model and simulate equipment to predict its performance, size, weight, and power.
  
  PHASE II: 1) Develop a compact, lightweight hardware prototype of the Phase I design. 2) Test the prototype in a terrestrial plasma chamber to establish performance characteristics. 3) Deliver an instrument that can be qualified for flight test.

  DUAL USE COMMERCIALIZATION: Military application: The technology developed in this effort applies directly to communication, navigation, reconnaissance, targeting, and battle damage assessment systems for future Air Force hypersonic air vehicles Commercial application: The technology developed in this effort will enhance the communication and navigation capabilities of future commercial spacelift and civil hypersonic aerospace systems, including those of NASA.

  References:   1. Grantham, W.L., “Reentry Plasma Measurements Using a Four-Frequency Reflectometer,” The Entry Plasma Sheath and Its Effects on Space Vehicle Electromagnetic Systems – Vol. I, NASA SP-252, National Aeronautics and Space Administration, 1970, pp. 65 - 108. 2. Swift, C.T., F.B. Beck, J. Thomson, and S.L. Castellow, Jr., “RAM C-III S-Band Diagnostic Experiment,” The Entry Plasma Sheath and Its Effects on Space Vehicle Electromagnetic Systems – Vol. I, NASA SP-252, National Aeronautics and Space Administration, 1970, pp. 137 - 156. 3. Poirier, J.L., W. Rotman, D.T. Hayes, J.F. Lennon, Effects of the Reentry Plasma Sheath on Microwave Antenna Performance: Trailblazer II Rocket Results of 18 June 1967, AFCRL-69-0354, Air Force Cambridge Research Laboratories, Bedford, MA August 1969. DTIC: AD0865522 4. Hayes, D.T., S.B. Herskovitz, J.F. Lennon, and J.L. Poirier, An Ablation Technique for Enhancing Reentry Antenna Performance: Flight Test Results, AFCRL-TR-74-0572, Air Force Cambridge Research Laboratories, Hanscom AFB, MA, November 1974. DTIC: ADA012250

Keywords:  hypersonic aircraft, plasmas (physics), electromagnetic radiation, atmosphere reentry, maneuverable reentry vehicles

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