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A refracting radio telescopeObservations of extraterrestrial radio sources at the lower end of the radio frequency spectrum are limited by reflection of waves from the topside ionosphere and by the large size of antenna apertures necessary for the realization of narrow beamwidths. The use of the ionosphere as a lens is considered. The lens is formed by the release of chemicals such as H2 and H2O at the F2-layer peak. These chemicals promote dissociative recombination of O(+) in the ionosphere resulting in a local reduction in plasma density. Gradients in electron density in the vicinity of the gas release tend to focus rays propagating through the depleted region. Preliminary calculations indicate that a lens capable of focusing cosmic radio waves in the 1 to 10 MHz frequency range may be produced by the release of 100 kg of H2 at the peak of the nighttime F layer. The beamwidth of a refracting radio telescope using this lens may be less than 1/5 degree.
Document ID
19770046863
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Bernhardt, P.
(Stanford Univ. CA, United States)
Da Rosa, A. V.
(Stanford University Stanford, Calif., United States)
Date Acquired
August 8, 2013
Publication Date
April 1, 1977
Publication Information
Publication: Radio Science
Volume: 12
Subject Category
Astronomy
Accession Number
77A29715
Funding Number(s)
CONTRACT_GRANT: NAS8-31769
CONTRACT_GRANT: NGR-05-020-001
Distribution Limits
Public
Copyright
Other

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