A Low-Perturbation Near-Field Imager Equipped with Optical MST Probes

Konferenz: EuCAP 2009 - 3rd European Conference on Antennas and Propagation
23.03.2009 - 27.03.2009 in Berlin, Germany

Tagungsband: EuCAP 2009

Seiten: 5Sprache: EnglischTyp: PDF

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Tehran, Hamidreza Memarzadeh; Laurin, Jean-Jacques; Kashyap, Raman (Department of Electrical Engineering, Ecole Polytechnique de Montreal, Montreal (QC) Canada H3C 3A7)

In this paper, the design and implementation of a near-field microwave imager based on a probe consisting of an optically modulated scatterer (OMS) is described and discussed. The probe uses a commercial-off-the-shelf (COTS) photodiode chip and a short dipole and it fulfils the requirements for a minimum scattering antenna. Measurement using this OMS probe is nearly perturbation-free due to the low scattering of the measured radio-frequency electric field by the optical fiber used to carry the modulating light signal. An array of OMS probes is then developed to eliminate or reduce the delays associated with a mechanical positioning system in a planar near-field setup. Optical power switching between the array elements is done with a switched laser diode array using a number of fiber-pigtailed laser diodes. The performance assessment of the near-field imager, including its linearity and accuracy, is made by comparisons with a known field distribution.