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Wavefront synthesis in a reverberation chamber: First experimental results

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Wavefront Synthesis in a Reverberation

Chamber: Experimental Results

Andrea Cozza, Florian Monsef

Pôle Physique et Ingénierie de l’Electromagnétisme

GeePs (UMR 8507), Université Paris Saclay

Contact : andrea.cozza@centralesupelec.fr

References

[1] A. Cozza, Physical Review E 80, 5 (2009)

[2] A. Cozza, H. Moussa, IET Electronics Letters 45, 25 (2009) [3] A. Cozza, IET Electronics Letters 46, 9 (2010)

[4] A. Cozza, H. Moussa, WO 2010/112763, (2010)

[5] A. Cozza, IEEE Transactions on Antennas and Propagation 60, 8 (2012) [6] P. Meton et al, EuCAP, Goteborg (2013)

Journées EMGE 2015, 2-3 décembre 2015, Onera, Toulouse, France

The TREC recipe in a nutshell: a) a weakly lossy diffusive

environment (e.g., a reverberation chamber), b) a single

source, with no special features and c) a scanning system

for sampling Green’s functions over a surface.

Fig. 1 : The robot optimized to weakly perturbate a

reverberation chamber in the GHz range. On the right, a detail showing the electro-optic probe.

First automated validation. Goals: a) to assess how

strongly the generated wavefronts contrast with the

diffusive background, b) they reproductibility and c) their

ability to generate spatially resolved EM stress.

-0.60 -40 -20 0 20 40 30 40 50 60 70 -0.14 -40 -20 0 20 40 30 40 50 60 70 0.60 -40 -20 0 20 40 30 40 50 60 70 -0.60 -40 -20 0 20 40 30 40 50 60 70 -0.14 -40 -20 0 20 40 30 40 50 60 70 0.60 -40 -20 0 20 40 30 40 50 60 70 -0.60 -40 -20 0 20 40 30 40 50 60 70 -0.14 -40 -20 0 20 40 30 40 50 60 70 0.60 -40 -20 0 20 40 30 40 50 60 70 -0.60 -40 -20 0 20 40 30 40 50 60 70 -0.14 -40 -20 0 20 40 30 40 50 60 70 0.60 -40 -20 0 20 40 30 40 50 60 70 -0.60 -40 -20 0 20 40 30 40 50 60 70 -0.14 -40 -20 0 20 40 30 40 50 60 70 0.60 -40 -20 0 20 40 30 40 50 60 70 -0.60 -40 -20 0 20 40 30 40 50 60 70 -0.14 -40 -20 0 20 40 30 40 50 60 70 0.60 -40 -20 0 20 40 30 40 50 60 70

Fig. 2 : Wavefronts sampled at three time instants over a vertical

plane, as they approach and leave the focal region (top to bottom): an example of local planar excitation (left column) and one limited by diffraction. -0.60 -40 -20 0 20 40 30 40 50 60 70 -0.60 -40 -20 0 20 40 30 40 50 60 70 -0.14 -40 -20 0 20 40 30 40 50 60 70 -0.14 -40 -20 0 20 40 30 40 50 60 70 0.60 -40 -20 0 20 40 30 40 50 60 70 0.60 -40 -20 0 20 40 30 40 50 60 70 -0.60 -40 -20 0 20 40 30 40 50 60 70 -0.60 -40 -20 0 20 40 30 40 50 60 70 -0.14 -40 -20 0 20 40 30 40 50 60 70 -0.14 -40 -20 0 20 40 30 40 50 60 70 0.60 -40 -20 0 20 40 30 40 50 60 70 0.60 -40 -20 0 20 40 30 40 50 60 70 -0.60 -40 -20 0 20 40 30 40 50 60 70 -0.60 -40 -20 0 20 40 30 40 50 60 70 -0.14 -40 -20 0 20 40 30 40 50 60 70 -0.14 -40 -20 0 20 40 30 40 50 60 70 0.60 -40 -20 0 20 40 30 40 50 60 70 0.60 -40 -20 0 20 40 30 40 50 60 70 -0.60 -40 -20 0 20 40 30 40 50 60 70 -0.60 -40 -20 0 20 40 30 40 50 60 70 -0.14 -40 -20 0 20 40 30 40 50 60 70 -0.14 -40 -20 0 20 40 30 40 50 60 70 0.60 -40 -20 0 20 40 30 40 50 60 70 0.60 -40 -20 0 20 40 30 40 50 60 70 -0.60 -40 -20 0 20 40 30 40 50 60 70 -0.60 -40 -20 0 20 40 30 40 50 60 70 -0.14 -40 -20 0 20 40 30 40 50 60 70 -0.14 -40 -20 0 20 40 30 40 50 60 70 0.60 -40 -20 0 20 40 30 40 50 60 70 0.60 -40 -20 0 20 40 30 40 50 60 70 -0.60 -40 -20 0 20 40 30 40 50 60 70 -0.60 -40 -20 0 20 40 30 40 50 60 70 -0.14 -40 -20 0 20 40 30 40 50 60 70 -0.14 -40 -20 0 20 40 30 40 50 60 70 0.60 -40 -20 0 20 40 30 40 50 60 70 0.60 -40 -20 0 20 40 30 40 50 60 70

Fig. 3 : Testing the wavefront repeatability after translation (left

column) and rotation (right column).

Observations: a) stable wavefronts against translation

and rotation, b) good level of contrast (> 20 dB), c) good

polarization control.

Applications : a promising application currently developed

is imaging coupling paths in metallic shields. An example

is shown below.

x (cm) z ( c m ) x excitation -20 0 20 -40 -30 -20 -10 0 10 20 30 40 -56 -54 -52 -50 -48 -46 -44 -42 -40 -38 x (cm) z ( c m ) z excitation -20 0 20 -40 -30 -20 -10 0 10 20 30 40 -56 -54 -52 -50 -48 -46 -44 -42 -40 -38 x (cm) z ( c m ) x excitation -20 0 20 -40 -30 -20 -10 0 10 20 30 40 -56 -54 -52 -50 -48 -46 -44 -42 -40 -38 x (cm) z ( c m ) z excitation -20 0 20 -40 -30 -20 -10 0 10 20 30 40 -56 -54 -52 -50 -48 -46 -44 -42 -40 -38

Fig. 4 : A transmission image of a slotted metal box, showing the

position of a slot and its sensitivity to polarization. Moving focal spots were used in order to generate it.

Figure

Fig. 2 : Wavefronts sampled at three time instants over a vertical plane, as they approach and leave the focal region (top to bottom): an example of local planar excitation (left column) and one limited by diffraction

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