Polarimetrisk väggpenetrerande radar. Teori, simuleringar och utvecklingsläge

Authors:

  • Ain Sume
  • Tommy Johansson

Publish date: 2010-05-27

Report number: FOI-R--2987--SE

Pages: 118

Written in: Swedish

Keywords:

  • "See-through-the-wall"
  • radar
  • polarisation
  • wave propagation
  • reflection
  • transmission
  • attenuation
  • wall penetration
  • urban
  • battlefield surveillance

Abstract

The report is a study of the properties and possible applications of electromagnetic polarisation in penetrating radar in urban scenarios. First, the principles of polarimetric measurements with radar are described, followed by a section describing the existing theory of electromagnetic wave propagation through media consisting of one or more homogeneous layers of various materials, including wall material. The theory handles reflection and transmission at the plane-parallell surfaces that separate the layers, which can be attenuating, and is applied to a multi-layered wall to study how the polarisation is transformed by the propagation through the wall. The main part of the report consists of an overview from a polarisation perspective of current views about the interaction of a radar wave with targets and background, after its passage through the wall. The overview gives an account of theoretical methods for optimization of target returns, or of contrasts between targets and backgrounds, by proper choice of the antenna polarisation on transmit and receive. An important method for improving contrast by the combined use of polarisation and the Doppler shift for moving objects is described. An account is given of the work of two international groups, consisting of simulations and measurements, where some of the mentioned methods are applied. One group has specifically studied by simulations the application at hand, viz. to observe a human target through a wall. The other group has developed theory for Doppler-polarimetric analysis, and applied it in measurements, however in another application. In the overview, no reported radar measurement has been found with full polarimetric capacity in the see-through application. In a proposal for a continuation of the FOI work the importance to acquire equipment with this capacity is stressed e.g. as an added facility to the existing measurement equipment on the FOI test ground at Lilla Gåra. The report contains an extensive appendix with general polarisation theory.

Share page on social media