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Open AccessArticle

On the Use of Focused Incident Near-Field Beams in Microwave Imaging

Department of Electrical and Computer Engineering, University of Manitoba, Winnipeg, MB R3T 5V6, Canada
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Sensors 2018, 18(9), 3127; https://doi.org/10.3390/s18093127
Received: 30 June 2018 / Revised: 21 August 2018 / Accepted: 7 September 2018 / Published: 17 September 2018
(This article belongs to the Special Issue Sensors for Microwave Imaging and Detection)
We consider the use of focused incident near-field (NF) beams to interrogate the object of interest (OI) in NF microwave imaging (MWI). To this end, we first discuss how focused NF beams can be advantageously utilized to suppress scattering effects from the neighbouring objects whose unknown dielectric properties are not of interest (i.e., undesired scatterers). We then discuss how this approach can also be helpful in reducing the required measured data points to perform imaging. Driven by the relation between the electromagnetic inverse source and inverse scattering problems, our approach emphasizes the importance of tailoring the induced contrast sources in the imaging domain through the utilized incident NF beams. To demonstrate this idea, we consider two recently-proposed NF beams, and simulate them for imaging applications. The first one is a subwavelength focused NF beam generated by a passive NF plate, and the other is a Bessel beam generated by a leaky radial waveguide. Simple imaging examples are considered to explore the potential advantages of this approach, in particular, toward mainly seeing the object of interest, and not the unknown undesired scatterers. The scope of this paper is limited to homogeneous dielectric objects for which the induced total field distributions in the interrogated objects are similar to the incident field distributions (e.g., those that satisfy the Born approximation). Simple inversion results for focused and non-focused beams are presented accompanied by discussions comparing the achieved reconstructed values. View Full-Text
Keywords: microwave imaging (MWI); near-field (NF) zone; sub-wavelength focusing; near-field plates; Bessel beams; inverse scattering; inverse source problems microwave imaging (MWI); near-field (NF) zone; sub-wavelength focusing; near-field plates; Bessel beams; inverse scattering; inverse source problems
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MDPI and ACS Style

Bayat, N.; Mojabi, P. On the Use of Focused Incident Near-Field Beams in Microwave Imaging. Sensors 2018, 18, 3127. https://doi.org/10.3390/s18093127

AMA Style

Bayat N, Mojabi P. On the Use of Focused Incident Near-Field Beams in Microwave Imaging. Sensors. 2018; 18(9):3127. https://doi.org/10.3390/s18093127

Chicago/Turabian Style

Bayat, Nozhan; Mojabi, Puyan. 2018. "On the Use of Focused Incident Near-Field Beams in Microwave Imaging" Sensors 18, no. 9: 3127. https://doi.org/10.3390/s18093127

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