Advanced

Optimal Electromagnetic Measurements

Cheney, Margaret LU and Kristensson, Gerhard LU (2000) In Technical Report LUTEDX/(TEAT-7091)/1-24/(2000) TEAT-7091.
Abstract
We consider the problem of obtaining information about an inaccessible halfspace

from electromagnetic measurements made in the accessible half-space.

If the measurements are of limited precision, some scatterers will be undetectable

because their scattered fields are below the precision of the measuring

instrument. How can we make optimal measurements? In other words, what

incident fields should we apply that will result in the biggest measurements?

There are many ways to formulate this question, depending on the measuring

instruments. In this paper we consider a formulation involving wavesplitting

in the accessible half-space: what downgoing wave will result in... (More)
We consider the problem of obtaining information about an inaccessible halfspace

from electromagnetic measurements made in the accessible half-space.

If the measurements are of limited precision, some scatterers will be undetectable

because their scattered fields are below the precision of the measuring

instrument. How can we make optimal measurements? In other words, what

incident fields should we apply that will result in the biggest measurements?

There are many ways to formulate this question, depending on the measuring

instruments. In this paper we consider a formulation involving wavesplitting

in the accessible half-space: what downgoing wave will result in an

upgoing wave of greatest energy? This formulation is most natural for far-field

problems.

A closely related question arises in the case when we have a guess about the

configuration of the inaccessible half-space. What measurements should we

make to determine whether our guess is accurate? In this case we compare the

scattered field to the field computed from the guessed configuration. Again

we look for the incident field that results in the greatest energy difference.

We show that the optimal incident field can be found by an iterative

process involving time reversal “mirrors”. For band-limited incident fields

and compactly supported scatterers, this iterative process converges to a sum

of time-harmonic fields. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Book/Report
publication status
published
subject
in
Technical Report LUTEDX/(TEAT-7091)/1-24/(2000)
volume
TEAT-7091
pages
24 pages
publisher
[Publisher information missing]
language
English
LU publication?
yes
id
50780362-0dc2-4f08-a610-e124aecb4a2c (old id 530568)
date added to LUP
2007-09-06 12:19:40
date last changed
2016-09-30 15:29:32
@misc{50780362-0dc2-4f08-a610-e124aecb4a2c,
  abstract     = {We consider the problem of obtaining information about an inaccessible halfspace<br/><br>
from electromagnetic measurements made in the accessible half-space.<br/><br>
If the measurements are of limited precision, some scatterers will be undetectable<br/><br>
because their scattered fields are below the precision of the measuring<br/><br>
instrument. How can we make optimal measurements? In other words, what<br/><br>
incident fields should we apply that will result in the biggest measurements?<br/><br>
There are many ways to formulate this question, depending on the measuring<br/><br>
instruments. In this paper we consider a formulation involving wavesplitting<br/><br>
in the accessible half-space: what downgoing wave will result in an<br/><br>
upgoing wave of greatest energy? This formulation is most natural for far-field<br/><br>
problems.<br/><br>
A closely related question arises in the case when we have a guess about the<br/><br>
configuration of the inaccessible half-space. What measurements should we<br/><br>
make to determine whether our guess is accurate? In this case we compare the<br/><br>
scattered field to the field computed from the guessed configuration. Again<br/><br>
we look for the incident field that results in the greatest energy difference.<br/><br>
We show that the optimal incident field can be found by an iterative<br/><br>
process involving time reversal “mirrors”. For band-limited incident fields<br/><br>
and compactly supported scatterers, this iterative process converges to a sum<br/><br>
of time-harmonic fields.},
  author       = {Cheney, Margaret and Kristensson, Gerhard},
  language     = {eng},
  pages        = {24},
  publisher    = {ARRAY(0xd6f3c60)},
  series       = {Technical Report LUTEDX/(TEAT-7091)/1-24/(2000)},
  title        = {Optimal Electromagnetic Measurements},
  volume       = {TEAT-7091},
  year         = {2000},
}