Senior Research Scholar, IIT Guwahati
Microwave Wireless power transfer
My research focuses on wireless power transfer using the microwave in far field for various applications ranging from biomedical applications, defence application etc. Using metamaterial in between the trasmitter and reciever side, I am trying to increase the effciency of the system.
Abstract: Wireless power transfer (WPT) has been an active topic of research, with a number of WPT schemes implemented in the near-field (coupling) and far-field (radiation) regimes. Here, we consider a beamed WPT scheme based on a dynamically reconfigurable source aperture transferring power to receiving devices within the Fresnel (near-zone) region. In this context, the dynamic aperture resembles a reconfigurable lens capable of focusing power to a well-defined spot, whose dimension can be related to a point spread function (PSF). Near-zone focusing can be achieved by generating different amplitude or phase profiles over the aperture, which can be realized using traditional architectures, such as phased arrays. Alternatively, metasurface guided-wave apertures can achieve dynamic focusing, with potentially lower cost implementations. We present an initial tradeoff analysis of the near-zone WPT concept, relating key parameters such as spot size, aperture size, wavelength, focal distance, and availability of sources. We find that approximate design formulas derived from the Gaussian optics approximation provide useful estimates of system performance, including transfer efficiency and coverage volume. The accuracy of these formulas is confirmed using numerical calculations.
Pub.: 21 Oct '16, Pinned: 28 Aug '17
Abstract: Diffraction restricts the ability of most electromagnetic devices to image or selectively target objects smaller than the wavelength. We describe planar subwavelength structures capable of focusing well beyond the diffraction limit, operating at arbitrary frequencies. The structure design, related to that of Fresnel plates, forces the input field to converge to a spot on the focal plane. However, unlike the diffraction-limited zone plates, for which focusing results from the interference of traveling waves, the subwavelength plates control the near field and, as such, their superlensing properties originate from a static form of interference. Practical implementations of these plates hold promise for near-field data storage, noncontact sensing, imaging, and nanolithography applications.
Pub.: 14 Jul '07, Pinned: 28 Aug '17
Abstract: Using a patterned, grating-like plate to control the electromagnetic near field, we demonstrate focusing well beyond the diffraction limit at approximately 1 gigahertz. The near-field plate consists of only capacitive elements and focuses microwaves emanating from a cylindrical source to a spot of size approximately lambda/20 (half-power beamwidth), where lambda is the free-space wavelength. These plates will find application in antennas, beam-shaping devices, nonradiative wireless power-transfer systems, microscopy, and lithography.
Pub.: 29 Apr '08, Pinned: 28 Aug '17
Abstract: Publication date: January 2017 Source:Optics and Lasers in Engineering, Volume 88 Author(s): Matthias P.L. Sentis, Laurent Bruel, Sophie Charton, Fabrice R.A. Onofri, Fabrice Lamadie An extended Generalized Fresnel Transform (GFT) is proposed to account for the astigmatism introduced by optical elements described, in the paraxial approximation, with a ray transfer matrix analysis. Generalized impulse response and generalized Fresnel transfer function propagators as well as sampling conditions are derived to properly implement this transformation. As a test case, the near-field diffraction patterns and in-line holograms produced by droplets flowing in a tube with cylindrical interfaces have been simulated. A best fitting approach is introduced to retrieve, from the propagated holograms, the 3D position and size of the droplets. Several hologram focusing indicators based on the analysis of droplets focus region are also proposed to further improve the estimation of the droplets position along the optical axis. Numerical simulations and experimental results confirm the applicability and accuracy of the proposed methods.
Pub.: 09 Oct '16, Pinned: 28 Aug '17