Radar Sounding Through the Earth's Ionosphere at 45 MHz

Anthony Freeman, Xiaoqing Pi, Essam Heggy

Research output: Contribution to journalArticle

6 Citations (Scopus)


Radar sounding from aircraft or ground-coupled radars has long provided scientists with a powerful technique to sound through ice layers to retrieve local depth and layering structure. More recently, it has been used to detect shallow aquifers in warm, dry, and desert regions. At Mars, a long-wavelength radar sounding from low orbit altitudes has produced global maps that reveal the presence of ice layering at all latitudes and glacial deposits on the flanks of volcanoes. Until now, sounding from the earth orbit at wavelengths long enough to penetrate ice sheets and arid sand was thought to be infeasible, because of the electromagnetic properties of the ionosphere. In this paper, we show that a radar sounding at frequencies as low as 45 MHz is, in fact, theoretically possible under viewing conditions that occur often enough to be practical. This conclusion opens up a previously unutilized portion of the electromagnetic spectrum for large-scale, spaceborne remote sensing of subsurface features on the earth.

Original languageEnglish
Article number7984840
Pages (from-to)5833-5842
Number of pages10
JournalIEEE Transactions on Geoscience and Remote Sensing
Issue number10
Publication statusPublished - 1 Oct 2017



  • Ionospheric propagation
  • radar sounding
  • very high frequency (VHF)

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Earth and Planetary Sciences(all)

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