Effect of the ionosphere on defocusing of space-based radars

Max van de Kamp*, Paul Cannon, Michael Terkildsen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)


[1] Space-based synthetic aperture radars can be detrimentally affected by electron density variations in the ionosphere, which cause signal phase variations resulting in image defocusing. In order to evaluate the significance of this problem, this paper determines how often the phase perturbations are large enough to cause defocusing. High cadence GPS TEC signals collected on Ascension Island during sunspot minimum and in Papua New Guinea over half a solar cycle have been analyzed. Both locations lie in the equatorial crest region. For a space-based synthetic radar operating at 435 MHz, the average probability of defocusing varies from zero at quiet times, to around 1% between 18:00 and 24:00 at solar minimum, and to 45% between 18:00 and 24:00 at solar maximum. Corresponding values are given for radars operating at other frequencies. A method is developed to estimate such variations from the large database of S4 measurements.
Original languageEnglish
Article numberRS1003
Number of pages15
JournalRadio Science
Issue number1
Early online date17 Jan 2009
Publication statusPublished - Feb 2009


  • ionospheric scintillation
  • synthetic aperture radars


Dive into the research topics of 'Effect of the ionosphere on defocusing of space-based radars'. Together they form a unique fingerprint.

Cite this