by crawler » Tue Dec 17, 2024 10:40 pm
galaxy12 wrote: ↑Tue Dec 17, 2024 8:46 pm
crawler wrote: ↑Tue Dec 17, 2024 8:18 pm
EM pulses ........... come from
antennas (ie from the movement of charge)(ie from elekticity, the movement of elektons).
Light photons...... come from atoms (ie the antenna is an atom)(ie atomic elektrons become photons).
According to this nature article, light can indeed by transmitted by antennas. Light is simply another electromagnetic frequency.
https://www.nature.com/articles/nphoton.2010.237
"Optical antennas are devices that convert freely propagating optical radiation into localized energy, and vice versa. They enable the control and manipulation of optical fields at the nanometre scale, and hold promise for enhancing the performance and efficiency of photodetection, light emission and sensing. Although many of the properties and parameters of optical antennas are similar to their radiowave and microwave counterparts, they have important differences resulting from their small size and the resonant properties of metal nanostructures."
Interesting. Here is what wiki says. As usual their mentions of electrons etc & em radiation etc is nonsense.
Optical rectenna From Wikipedia, the free encyclopedia
Figure 1. Spectral irradiance of wavelengths in the solar spectrum. The red shaded area shows the irradiance at sea level. There is less irradiance at sea level due to absorption of light by the atmosphere.
An optical rectenna is a rectenna (rectifying antenna) that works with visible or infrared light.[1] A rectenna is a circuit containing an antenna and a diode, which turns electromagnetic waves into direct current electricity. While rectennas have long been used for radio waves or microwaves, an optical rectenna would operate the same way but with infrared or visible light, turning it into electricity.
While traditional (radio- and microwave) rectennas are fundamentally similar to optical rectennas, it is vastly more challenging in practice to make an optical rectenna. One challenge is that light has such a high frequency—hundreds of terahertz for visible light—that only a few types of specialized diodes can switch quickly enough to rectify it. Another challenge is that antennas tend to be a similar size to a wavelength, so a very tiny optical antenna requires a challenging nanotechnology fabrication process. A third challenge is that, being very small, an optical antenna typically absorbs very little power, and therefore tend to produce a tiny voltage in the diode, which leads to low diode nonlinearity and hence low efficiency. Due to these and other challenges, optical rectennas have so far been restricted to laboratory demonstrations, typically with intense focused laser light producing a tiny but measurable amount of power.
Nevertheless, it is hoped that arrays of optical rectennas could eventually be an efficient means of converting sunlight into electric power, producing solar power more efficiently than conventional solar cells. The idea was first proposed by Robert L. Bailey in 1972.[2] As of 2012, only a few optical rectenna devices have been built, demonstrating only that energy conversion is possible.[3] It is unknown if they will ever be as cost-effective or efficient as conventional photovoltaic cells.
The term nantenna (nano-antenna) is sometimes used to refer to either an optical rectenna, or an optical antenna by itself. [4] In 2008 it was reported that Idaho National Laboratories designed an optical antenna to absorb wavelengths in the range of 3–15 μm.[5] These wavelengths correspond to photon energies of 0.4 eV down to 0.08 eV. Based on antenna theory, an optical antenna can absorb any wavelength of light efficiently provided that the size of the antenna is optimized for that specific wavelength. Ideally, antennas would be used to absorb light at wavelengths between 0.4 and 1.6 μm because these wavelengths have higher energy than far-infrared (longer wavelengths) and make up about 85% of the solar radiation spectrum[6] (see Figure 1)……………………
Theory
The theory behind optical rectennas is essentially the same as for traditional (radio or microwave) 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 (AC) in the antenna circuit. To convert this into direct current (DC), the AC must be rectified, which is typically done with a 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.[6] The wavelengths in the solar spectrum range from approximately 0.3-2.0 μm.[6] Thus, in order for a rectifying antenna to be an efficient electromagnetic collector in the solar spectrum, it needs to be on the order of hundreds of nm in size……………….
Figure 3. Image showing the skin effect at high frequencies. The dark region, at the surface, indicates electron flow where the lighter region (interior) indicates little to no electron flow.
Because of simplifications used in typical rectifying antenna theory, there are several complications that arise when discussing optical rectennas. At frequencies above infrared, almost all of the current is carried near the surface of the wire which reduces the effective cross sectional area of the wire, leading to an increase in resistance. This effect is also known as the "skin effect". From a purely device perspective, the I-V characteristics would appear to no longer be ohmic, even though Ohm's law, in its generalized vector form, is still valid.[quote=galaxy12 post_id=11204 time=1734468413 user_id=1000000325]
[quote=crawler post_id=11203 time=1734466711 user_id=30412]
[b][size=150]EM pulses[/size][/b] ........... come from [b][u]antennas[/u][/b] (ie from the movement of charge)(ie from elekticity, the movement of elektons).
[color=#4000BF][b][size=150]Light photons[/size][/b]...... come from [b][u]atoms[/u][/b] (ie the antenna is an atom)(ie atomic elektrons become photons).[/color][/quote]
According to this nature article, light can indeed by transmitted by antennas. Light is simply another electromagnetic frequency.
https://www.nature.com/articles/nphoton.2010.237
"Optical antennas are devices that convert freely propagating optical radiation into localized energy, and vice versa. They enable the control and manipulation of optical fields at the nanometre scale, and hold promise for enhancing the performance and efficiency of photodetection, light emission and sensing. Although many of the properties and parameters of optical antennas are similar to their radiowave and microwave counterparts, they have important differences resulting from their small size and the resonant properties of metal nanostructures."[/quote]
Interesting. Here is what wiki says. As usual their mentions of electrons etc & em radiation etc is nonsense.
[i][b][u][size=150]Optical rectenna [/size][/u][/b] From Wikipedia, the free encyclopedia
Figure 1. Spectral irradiance of wavelengths in the solar spectrum. The red shaded area shows the irradiance at sea level. There is less irradiance at sea level due to absorption of light by the atmosphere.
An optical rectenna is a rectenna (rectifying antenna) that works with visible or infrared light.[1] A rectenna is a circuit containing an antenna and a diode, which turns electromagnetic waves into direct current electricity. While rectennas have long been used for radio waves or microwaves, an optical rectenna would operate the same way but with infrared or visible light, turning it into electricity.
While traditional (radio- and microwave) rectennas are fundamentally similar to optical rectennas, it is vastly more challenging in practice to make an optical rectenna. One challenge is that light has such a high frequency—hundreds of terahertz for visible light—that only a few types of specialized diodes can switch quickly enough to rectify it. Another challenge is that antennas tend to be a similar size to a wavelength, so a very tiny optical antenna requires a challenging nanotechnology fabrication process. A third challenge is that, being very small, an optical antenna typically absorbs very little power, and therefore tend to produce a tiny voltage in the diode, which leads to low diode nonlinearity and hence low efficiency. Due to these and other challenges, optical rectennas have so far been restricted to laboratory demonstrations, typically with intense focused laser light producing a tiny but measurable amount of power.
Nevertheless, it is hoped that arrays of optical rectennas could eventually be an efficient means of converting sunlight into electric power, producing solar power more efficiently than conventional solar cells. The idea was first proposed by Robert L. Bailey in 1972.[2] As of 2012, only a few optical rectenna devices have been built, demonstrating only that energy conversion is possible.[3] It is unknown if they will ever be as cost-effective or efficient as conventional photovoltaic cells.
The term nantenna (nano-antenna) is sometimes used to refer to either an optical rectenna, or an optical antenna by itself. [4] In 2008 it was reported that Idaho National Laboratories designed an optical antenna to absorb wavelengths in the range of 3–15 μm.[5] These wavelengths correspond to photon energies of 0.4 eV down to 0.08 eV. Based on antenna theory, an optical antenna can absorb any wavelength of light efficiently provided that the size of the antenna is optimized for that specific wavelength. Ideally, antennas would be used to absorb light at wavelengths between 0.4 and 1.6 μm because these wavelengths have higher energy than far-infrared (longer wavelengths) and make up about 85% of the solar radiation spectrum[6] (see Figure 1)……………………
[b][u][size=150]Theory[/size][/u][/b]
The theory behind optical rectennas is essentially the same as for traditional (radio or microwave) 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 (AC) in the antenna circuit. To convert this into direct current (DC), the AC must be rectified, which is typically done with a 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.[6] The wavelengths in the solar spectrum range from approximately 0.3-2.0 μm.[6] Thus, in order for a rectifying antenna to be an efficient electromagnetic collector in the solar spectrum, it needs to be on the order of hundreds of nm in size……………….
Figure 3. Image showing the skin effect at high frequencies. The dark region, at the surface, indicates electron flow where the lighter region (interior) indicates little to no electron flow.
Because of simplifications used in typical rectifying antenna theory, there are several complications that arise when discussing optical rectennas. At frequencies above infrared, almost all of the current is carried near the surface of the wire which reduces the effective cross sectional area of the wire, leading to an increase in resistance. This effect is also known as the "skin effect". From a purely device perspective, the I-V characteristics would appear to no longer be ohmic, even though Ohm's law, in its generalized vector form, is still valid.[/i]