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B. C. Hicks, K. P. Stewart, N. Paravastu (NRL), R. F. Bradley, C. R. Parashare (NRAO), W. C. Erickson (University of Tasmania), C. Gross, E. Polisensky, P. C. Crane, P. S. Ray, N. E. Kassim, K. W. Weiler (NRL)
We present new designs for active antenna systems optimized for HF/VHF radio astronomy, ionospheric science, space weather, and other radio science applications. Active antenna designs have been developed and tested which satisfy the need for high linearity and stability while achieving Galactic background dominated noise levels. The presence of very strong terrestrial radio-frequency interference (RFI), and world-wide propagation at these frequencies require that the preamplifiers have very high dynamic range. Distortion products must be below the Galactic background level for RFI mitigation techniques to be successful. Individual antennas should have broad response patterns to cover most of the sky without pointing mechanisms, but with decreased sensitivity at low elevations. Ideal designs would also be immune to environmental effects such as temperature variations and precipitation. For projects such as the LWA, where thousands of receptors will be needed, they must also be robust, inexpensive, and easy to manufacture and install. We discuss high-performance designs that are optimized for cost-sensitive applications such as the LWA.
Basic research in astronomy is supported by the Office of Naval Research.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.