07-02-2013, 01:13 PM
NANOANTENNA-AN APPLICATION OF NANOTECHNOLOGY
[attachment=49996]
Abstract:
A nantenna (nanoantenna) is a nanosopic rectifying antenna, an experimental technology being developed to convert light to electric power. The concept is based on the rectenna (rectifying antenna), a device used in wireless power transmission. A re-ctenna is a specialized radio antenna which is used to convert radio waves into direct current electricity. Light is composed of electromagnetic waves like radio waves but of much smaller wavelength. A nantenna is a very small rectenna the size of a light wave, fabricated using nanotechnology, which acts as an "antenna" for light, converting light into electricity. It is hoped that arrays of nantennas could be an efficient means of converting sunlight into electric power, producing solar power more efficiently than conventional solar cells.
Introduction
The idea was first proposed by Robert L. Bailey in 1972. As of 2012, only a few nantenna devices have been built, demonstrating only that energy conversion is possible. It is unknown if they will ever be as cost-effective as photovoltaic cells.A nantenna is an electromagnetic collector designed to absorb specific wavelengths that are proportional to the size of the nantenna. Currently nanoantennas are designed to operate wavelengths in the range of 3–15 μm. These wavelengths correspond to photon energies of 0.08 –
0.4 eV. Based on antenna theory, a nantenna can absorb any wavelength of light efficiently provided that the size of the nantenna is optimized for that specific wavelength.
Nanotechnology builds on advances in microelectronics during the last decades of the twentieth century. The miniaturization of electrical components greatly increased the utility and portability of computers, imaging equipment, microphones, and otherelectronics.
Nanotechnology is the manipulation of matter on an atomic and molecular scale. Generally, nanotechnology works with materials, devices, and other structures with at least one dimension sized from 1 to 100 nanometres. Nanotechnology may be able to create many new materials and devices with a vast range of applications, such as in medicine, electronics, biomaterials and energy production.
Theory of nanoantennas
The theory behind nantennas is essentially the same for rectifying antennas. Incident light on the antenna causes electrons in the antenna to move back and forth at the same frequency as the incoming light. This is caused by the oscillating electric field of the incoming electromagnetic wave. The movement of electrons is an alternating current in the antenna circuit. To convert this into direct current, the AC must be rectified, which is typically done with some kind of diode. The resulting DC current can then be used to power an external load. The resonant frequency of antennas (frequency which results in lowest impedance and thus highest efficiency) scales linearly with the physical dimensions of the antenna according to simple microwave antenna theory. The wavelengths in the solar spectrum range from approximately 0.3-2.0 μm.
Proof of principle
The proof of principle for nantennas started out with a 1 cm2 silicon substrate with the printed nantenna array filling the area. The device was tested using infrared light with a range of 3 to 15 microns. The peak emissivity is found to be centered at 6.5 microns and reaches an emissivity of 1. An emissivity of 1 means the nantenna absorbs all of the photons of a specific wavelength (in this case, 6.5 microns) that are incident upon the device. Comparing the experimental spectrum to the modeled spectrum, the experimental results are in agreement with theoretical expectations (Figure 5). In some areas, the nantenna had a lower emissivity than the theoretical expectations, but in other areas, namely at around 3.5 microns, the device absorbed more light than expected.
Conclusion
Currently, the largest problem is not with the antenna device, but with the rectifier. As previously stated, present-day diodes are unable to efficiently rectify at frequencies which correspond to high-infrared and visible light. Therefore, a rectifier must be designed that can properly turn the absorbed light into usable energy. Researchers currently hope to create a rectifier which can convert around 50% of the antenna's absorption into energy Another focus of research will be how to properly upscale the process to mass-market production. New materials will need to be chosen and tested that will easily comply with a roll-to-roll manufacturing process.
[attachment=49996]
Abstract:
A nantenna (nanoantenna) is a nanosopic rectifying antenna, an experimental technology being developed to convert light to electric power. The concept is based on the rectenna (rectifying antenna), a device used in wireless power transmission. A re-ctenna is a specialized radio antenna which is used to convert radio waves into direct current electricity. Light is composed of electromagnetic waves like radio waves but of much smaller wavelength. A nantenna is a very small rectenna the size of a light wave, fabricated using nanotechnology, which acts as an "antenna" for light, converting light into electricity. It is hoped that arrays of nantennas could be an efficient means of converting sunlight into electric power, producing solar power more efficiently than conventional solar cells.
Introduction
The idea was first proposed by Robert L. Bailey in 1972. As of 2012, only a few nantenna devices have been built, demonstrating only that energy conversion is possible. It is unknown if they will ever be as cost-effective as photovoltaic cells.A nantenna is an electromagnetic collector designed to absorb specific wavelengths that are proportional to the size of the nantenna. Currently nanoantennas are designed to operate wavelengths in the range of 3–15 μm. These wavelengths correspond to photon energies of 0.08 –
0.4 eV. Based on antenna theory, a nantenna can absorb any wavelength of light efficiently provided that the size of the nantenna is optimized for that specific wavelength.
Nanotechnology builds on advances in microelectronics during the last decades of the twentieth century. The miniaturization of electrical components greatly increased the utility and portability of computers, imaging equipment, microphones, and otherelectronics.
Nanotechnology is the manipulation of matter on an atomic and molecular scale. Generally, nanotechnology works with materials, devices, and other structures with at least one dimension sized from 1 to 100 nanometres. Nanotechnology may be able to create many new materials and devices with a vast range of applications, such as in medicine, electronics, biomaterials and energy production.
Theory of nanoantennas
The theory behind nantennas is essentially the same for rectifying antennas. Incident light on the antenna causes electrons in the antenna to move back and forth at the same frequency as the incoming light. This is caused by the oscillating electric field of the incoming electromagnetic wave. The movement of electrons is an alternating current in the antenna circuit. To convert this into direct current, the AC must be rectified, which is typically done with some kind of diode. The resulting DC current can then be used to power an external load. The resonant frequency of antennas (frequency which results in lowest impedance and thus highest efficiency) scales linearly with the physical dimensions of the antenna according to simple microwave antenna theory. The wavelengths in the solar spectrum range from approximately 0.3-2.0 μm.
Proof of principle
The proof of principle for nantennas started out with a 1 cm2 silicon substrate with the printed nantenna array filling the area. The device was tested using infrared light with a range of 3 to 15 microns. The peak emissivity is found to be centered at 6.5 microns and reaches an emissivity of 1. An emissivity of 1 means the nantenna absorbs all of the photons of a specific wavelength (in this case, 6.5 microns) that are incident upon the device. Comparing the experimental spectrum to the modeled spectrum, the experimental results are in agreement with theoretical expectations (Figure 5). In some areas, the nantenna had a lower emissivity than the theoretical expectations, but in other areas, namely at around 3.5 microns, the device absorbed more light than expected.
Conclusion
Currently, the largest problem is not with the antenna device, but with the rectifier. As previously stated, present-day diodes are unable to efficiently rectify at frequencies which correspond to high-infrared and visible light. Therefore, a rectifier must be designed that can properly turn the absorbed light into usable energy. Researchers currently hope to create a rectifier which can convert around 50% of the antenna's absorption into energy Another focus of research will be how to properly upscale the process to mass-market production. New materials will need to be chosen and tested that will easily comply with a roll-to-roll manufacturing process.