Physical Characteristics of Plasma Antennas

John Rayner, Adrian Whichello, Andrew Cheetham

    Research output: Contribution to journalArticle

    204 Citations (Scopus)
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    Abstract

    This experimental and theoretical study examines the
    excitation of a plasma antenna using an argon surface wave discharge operating at 500 MHz with RF power levels up to 120 W
    and gas pressures between 0.03 and 0.5 mb. The results show that
    the length of the plasma column increases as the square root of
    the applied power and that the plasma density decreases linearly
    from the wave launcher to the end of the plasma column. These results are consistent with a simple global model of the antenna. Since
    noise is critical to communication systems, the noise generated by
    the plasma was measured from 10 to 250 MHz. Between 50 and 250
    MHz the excess noise temperature was found to be 17.2 1.0 dB
    above 290 K. This corresponds to an ohmic thermal noise source
    at 1.4 0.3 eV, compared with an electron temperature of 1.65 eV
    predicted by the global model. Estimates of the electrical conductivity of the plasma column based on measured electron number
    densities lead to an antenna efficiency of about 65% at a transmission frequency of 100 MHz and an increase in total antenna noise
    of 1 dB due to the plasma. Theoretical modeling and experimental
    observations of the radiation pattern of the antenna show that the
    linear variation of conductivity and finite resistance of the column
    lead to a reduction in the depth of the nulls in the radiation pattern
    and a consequent increase in the width of the main lobe
    Original languageEnglish
    Pages (from-to)269-281
    Number of pages13
    JournalIEEE Transactions on Plasma Science
    Volume32
    Issue number1
    DOIs
    Publication statusPublished - 2004

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