Sunday, November 10, 2013

Tesla re-visited: "A microwave metamaterial with integrated power harvesting functionality"

The Daily Mail Online has a post with the following headlines

New invention 'harvests' electricity from background radiation and could be used to beam power to remote locations or recharge phones wirelessly

Device captures microwaves and converts them into electricity

Future versions could harvest satellite, sound or Wi-Fi signals

Technology could be used to recharge phones without cables or beam electricity to mountaintop

The initial text

Engineers at Duke University have designed a breakthrough gadget that 'harvests' background microwave radiation and converts it into electricity, with the same efficiency as solar panels.
The development, unveiled on Thursday, raises exciting possibilities such as recharging a phone wirelessly and providing power to remote locations that can't access conventional electricity.

Relevant scientific publication: "A microwave metamaterial with integrated power harvesting functionality," Allen M. Hawkes, Alexander R. Katko, and Steven A. Cummer. Applied Physics Letters 103, 163901 (2013); doi: 10.1063/1.4824473

Earlier patent application by Cummer: 20100289715, titled Metamaterial particles having active electronic components and related methods, which includes the text:

[0004] Metamaterials are a new class of ordered composites that exhibit exceptional properties not readily observed in nature. These properties arise from qualitatively new response functions that are not observed in the constituent materials and result from the inclusion of artificially fabricated, extrinsic, low dimensional inhomogeneities, which may be referred to as "metamaterial particles". These artificial composites can achieve material performance beyond the limitations of conventional composites. To date, most of the scientific activity with regard to metamaterials has centered on their electromagnetic properties.

[0005] Metamaterials can be used to engineer electromagnetic properties of a material by embedding numerous small metamaterial particles in a host matrix. These particles can produce an electric or magnetic dipole moment in response to an applied field. Metamaterials have properties that could potentially be used to fabricate super lenses, miniaturized antennas, enhanced tunneling effect devices, and invisibility cloaks. Electric and magnetic metamaterials have been extensively analyzed theoretically, in simulations, and tested experimentally, and are currently built by putting together arrays of passive subwavelength resonant particles, such as split-ring-resonators (SRRs), omega particles, electric-field-coupled resonators (ELCs), and cut-wires.

[0006] The currents and charges in these passive, self-resonant circuits created in response to an applied electric or magnetic field near the resonant frequency are great enough to generate electric or magnetic dipole moments that are in turn great enough to substantially alter the effective permittivity or permeability of a medium composed of these particles. However, exploiting this strong response close to resonance usually means significant losses and strongly frequency dependent properties, two consequences undesirable in many potential metamaterial applications. For example, it has been shown both theoretically and experimentally that the smallest amount of loss could significantly influence the effectiveness of the evanescent wave enhancement property responsible for the super lens and enhanced tunneling effects. On the other hand, it has been shown that even modest loss tangents of 0.01 can rarely be achieved in these metamaterials. Also, due to their resonant nature, the inherent high dispersion of current metamaterials makes them useful only for narrow bandwidth applications.

Press Release of November 7, 2013

From wikipedia on wireless power:

1891: Tesla demonstrates wireless energy transmission by means of electrostatic induction using a high-tension induction coil before the American Institute of Electrical Engineers at Columbia College

1902: Nikola Tesla vs. Reginald Fessenden – U.S. Patent Interference No. 21,701, System of Signaling (wireless); wireless power transmission, time and frequency domain spread spectrum telecommunications, electronic logic gates in general

2000: Prof. Shu Yuen (Ron) Hui invent a planar wireless charging pad using the "vertical flux" approach and resonant power transfer for charging portable consumer electronic products. A patent [application] is filed on "Apparatus and method of an inductive battery charger,” PCT Patent PCT/AU03/00 721, 2000.


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