## Sensitivity of electromagnetic waves
to a heterogeneous bianisotropic structure

**Ludek Klimes**
### Summary

We study how the perturbations of a generally heterogeneous
bianisotropic structure manifest themselves
in the wave field, and which perturbations can be detected
within a limited aperture and a limited frequency band.
A short-duration broad-band incident wave field
with a smooth frequency spectrum is considered.
Infinitesimally small perturbations of the constitutive tensor
are decomposed into Gabor functions.
The wave field scattered by the perturbations is then composed of
waves scattered by the individual Gabor functions.
The scattered waves are estimated using
the first-order Born approximation with
the paraxial ray approximation.

For each incident wave,
each Gabor function acts like a 3-D Bragg grating
and generates at the most 3 scattered Gaussian packets
propagating in specific directions.

For a particular source, each Gaussian packet scattered
by a Gabor function centred at a given spatial location
is sensitive to just a single linear combination
of the elements of the constitutive tensor
corresponding to the Gabor function.
This information about the Gabor function is lost
if the scattered Gaussian packet does not fall into the aperture
covered by the receivers
and into the legible frequency band.

### Whole paper

The paper is available in
PDF (333 kB).

Invited paper for the
*URSI 2010 International Symposium on Electromagnetic Theory*,
Berlin, Germany, August 16-19, 2010,
but with corrected equations (14) and (33).

In: Seismic Waves in Complex 3-D Structures, Report 20,
pp. 207-213, Dep. Geophys., Charles Univ., Prague, 2010.