Fabrication and electromagnetic characterization of novel self-metallized thin films
Unique, self-metallized films were investigated for deployable reflector antenna applications at L-band. Polyamic acid resins or soluble polyimides were doped with metal complexes, cast into films, and thermally cured. Each resulting film had a metallic layer on one side, adhering unfailingly to the polymer. Metallization was successful for silver or palladium in 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride (BTDA) and 4,4'- oxydianiline and for gold in BTDA and 2,2-bis[4-(4- aminophenoxy)phenyl]hexafluoropropane (4-BDAF) or the space durable polyimide, 2,2-bis(3,4-dicarboxyphenyl)- hexafluoropropane dianhydride and 4-BDAF (LaRCCP1). Reflectivity, transmissivity, and emissivity were determined, using an HP 8510 Vector Network Analyzer, to within 0.001 precision and accuracy. A custom-made test fixture/positioner, a thru-reflect-line calibration, and calculated reflection coefficients were used. The Ag film proved most suitable for further study, with 0.9957 reflectivity and 0.0042 emissivity. The Pd films were 0.89 reflective and 0.11 emissive; both Au films tested entirely transmissive. Transmission and scanning electron micrographs, S-parameters, and power coefficients are shown.
Photostabilization Studies Of Silver/Polymethylmethacrylate Films
Degradation of the optical performance by ultraviolet (UV) light is currently one of the principal barriers in the development of silver/polymer films for solar thermal applications. We have conclusively shown that stabilizers added to polymer films do improve the weatherability of mirrors, and we have identified a series of representative examples within the most commonly used groups of UV stabilizers and incorporated them into polymethylmethacrylate (PMMA) to enhance its effectiveness. We have found that the permanence of the stabilizers may limit mirror durability and that the stabilizer performance slowly diminishes because of photolysis and/or leaching and removal from the host polymer. Polymeric stabilizers are of interest on the basis that they will not leach from the host. Various polymeric UV-absorbing stabilizers have been synthesized from derivatives of 2-hydroxybenzophenone and 2-hydroxyphenylbenzotriazole. The relative effectiveness of the stabilizers in acrylic films will be discussed in terms of the weathering modes and retention of optical properties.
Inflatable Antenna Technology with Preliminary Shuttle Experiment Results and Potential Applications
This paper describes the status of NASA’s Inflatable Antenna Experiment (IAE) and a brief discussion on potential future applications. The space experiment of a 14-meter diameter reflector antenna was flown and deployed successfully aboard the Space Shuttle, STS77, launched May 19, 1996. Since the flight data is still being processed and reduced, only preliminary results can be presented at this time. The development of the IAE will be discussed along with the results of ground test measurements which were conducted to determine the overall mechanical and projected electrical performance characteristics of this inflatable concept. Large, spacedeployable antennas are needed for numerous applications which include mobile communications, Earth remote sensing, and space-based radar systems. Due to the traditionally high cost to develop and launch such large antennas, new technology must be developed which is cheaper, faster, and better. Inflatable antenna technology provides the opportunity to accomplish these objectives.