Premium
A refracting radio telescope
Author(s) -
Bernhardt Paul,
da Rosa A. V.
Publication year - 1977
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/rs012i002p00327
Subject(s) - ionosphere , beamwidth , physics , radio wave , optics , lens (geology) , radio telescope , telescope , electron density , reflection (computer programming) , plasma , ionospheric heater , antenna (radio) , astronomy , telecommunications , quantum mechanics , computer science , programming language
Observations 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 H 2 and H 2 O at the F 2 ‐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 H 2 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.