Glenn
2012-03-07 20:53:11 UTC
(Svar sendes til nntp://dk.fritid.hamradio )
Hvem kan forklare mig forskellen mellem cirkular polarisation - og
elektromagnetisk(f.eks. lys, radiobølger...) orbital angular momentum
(OAM)-bølger? - eller henvise til dansk eller engelsk litteratur om det?
Bispørgsmål - er der en relation mellem kvantemekanisk spin og OAM?
Hvis det virkelig er rigtigt, betyder det at man bl.a. kan lave nye?:
* bedre optiske mikroskoper
* finde materialer som fungerer ligesom polariserende stoffer a la
LCD-polarisationsfiltre, men til OAM.
* som de skriver i New Journal of Physics-artiklen - større effektiv
udnyttet båndbredde - jeg kan dog ikke se hvordan båndbredde kan
bibeholdes for varierende modulation af OAM-kanaler.
Nogen burde gå forrest og teste om det virker?
* Hvorfor kan en opklippet og passende bøjet reflektor (se New Journal
of Physics-artiklen, "Figure A4. The helicoidal parabolic antenna") have
en sådan OAM virkning?
* Er vandret/lodret/venstre/højre-drejede polarisationer ortogonale på
OAM-bølger? (måske varierer effekten/fænomenet med afstanden?)
* Kan en yagi/helical-antenne laves om til en OAM-antenne ved at klippe
og bøje en cirkulær reflektor? Ligesom parabolreflektoren i New Journal
of Physics-artiklen?
* Kan en yagi/helical-antenne laves om til en OAM-antenne uden at pille
ved reflektoren?
* Findes der naturlige radiobølge objekt passeringer/reflekteringer, som
konverterer en traditionel radiobølge til en eller anden OAM-radiobølge?
* Radar burde i den grad kunne få gavn af OAM-bølger?
* kan man sende og identificere OAM-superpositioner? F.eks. burde man
kunne skelne mellem 3-OAM, 5-OAM og 7-OAM, uanset om de reflekteres
eller lægges sammen med andre?
* Kan (-1_OAM) + (+1_OAM) ophæve hinanden?
* kan to ens antenner som sender samme OAM-superposition, "lægges"
sammen eller vil de interferere anderledes end traditionelle polarisationer?
Benytter "spatial_multiplexing" i virkeligheden OAM?:
http://en.wikipedia.org/wiki/Spatial_multiplexing
Functions of MIMO:
http://en.wikipedia.org/wiki/MIMO#Functions_of_MIMO
Citat: "…
In spatial multiplexing, a high rate signal is split into multiple lower
rate streams and each stream is transmitted from a different transmit
antenna in the same frequency channel. If these signals arrive at the
receiver antenna array with sufficiently different spatial signatures,
the receiver can separate these streams into (almost) parallel channels.
Spatial multiplexing is a very powerful technique for increasing channel
capacity at higher signal-to-noise ratios (SNR). The maximum number of
spatial streams is limited by the lesser of the number of antennas at
the transmitter or receiver.
…"
-
Akustiske bølger med OAM-lignende egenskab i faststof eller måske også i
væske og gas (luft)?:
* Har akustiske bølger (f.eks. lydbølger) også mulighed for
"OAM"-lignende-bølger? Bruger flagermus dem (uden at vide det)? Sonar
kan i så fald forbedres?
* Kan visse tryk/seismiske/jordskælvsbølger benytte "OAM"-lignende-bølger?
* Det kan anvendes til at afdække mineral og olie/gas-forekomster bedre?
-
Hvad med andre bølgetyper? Findes de også i "OAM"-lignende-bølger?
Kan graviationsbølger f.eks. lettere afdækkes hvis de modtages opløst i
OAM-"polariseringer"?
-
Mar 7, 2012, Physicists put a new twist on radio:
http://physicsworld.com/cws/article/news/48869
Citat: "...
Physicists have known for many years that a beam of light can be twisted
so that its wavefront rotates around its direction of propagation in a
spiral shape. The twisting is achieved by controlling the orbital
angular momentum of the light. This property is associated with the
shape of a light beam's wavefront – the imaginary line or plane joining
the points on a wave that have the same phase.
The orbital angular momentum should not be confused with the more
familiar spin angular momentum of light, which is associated with a
wave's polarization or direction of oscillation.
...
[Jeg kunne godt tænke mig en demonstration med 4 eller 8 OAM-kanaler -
to er ikke nok - måske er det i virkeligheden de 2 ortogonale
venstre/højre-drejede polarisationskanaler de sender og modtager?: ]
A specially adapted satellite-dish-style antenna on the lighthouse on St
George's Island was used to create radio waves with a frequency of 2.4
GHz and an orbital angular momentum of 1 – the latter meaning that the
wavefront is rotated 360° in the space of one wavelength. A standard
"Yagi" antenna was also used to send waves of the same frequency but
without orbital angular momentum across the same stretch of lagoon.
...
[ Det tyder på, at det IKKE er 2 ortogonale venstre/højre-drejede
polarisationskanaler?: ]
By varying the distance between the two receiving antennas on the
balcony of the Doge's Palace, the researchers were able to tune in to
either the twisted or the untwisted beam. This proves, they say, that
they were able to transmit two channels simultaneously using just a
single frequency.
...
[ En af gulerødderne - hvis det er rigtigt: ]
it means in principle being able to create an infinite number of
channels in a given bandwidth, with each channel encoded using a
different orbital angular momentum.
..."
1 marts 2012, Encoding many channels on the same frequency through radio
vorticity: first experimental test:
http://iopscience.iop.org/1367-2630/14/3/033001/article
-
Light orbital angular momentum:
http://en.wikipedia.org/wiki/Light_orbital_angular_momentum
Circular polarization:
http://en.wikipedia.org/wiki/Circular_polarization
Spin (physics):
http://en.wikipedia.org/wiki/Spin_%28physics%29
Citat: "...
Standard model of particle physics; hence bosons are also called force
carriers. These bosons have s=1.
...
Theory predicts the existence of two bosons whose s differs from 1. The
force carrier for gravity is the hypothetical graviton; theory suggests
that it has s = 2. The Higgs mechanism predicts that elementary
particles acquire nonzero rest mass by exchanging hypothetical Higgs
bosons with an all-pervasive Higgs field. Theory predicts that the Higgs
boson has s = 0. If so, it would be the only elementary particle for
which this is the case.
..."
Photon:
http://en.wikipedia.org/wiki/Photon
Citat: "...
Spin 1
...
The photon is massless,[Note 2] has no electric charge,[12] and is
stable. A photon has two possible polarization states and is described
by exactly three continuous parameters: the components of its wave
vector, which determine its wavelength lambda and its direction of
propagation.
...
The photon also carries spin angular momentum that does not depend on
its frequency.[17] The magnitude of its spin is \scriptstyle{\sqrt{2}
\hbar} and the component measured along its direction of motion, its
helicity, must be +-h. These two possible helicities, called
right-handed and left-handed, correspond to the two possible circular
polarization states of the photon.[18]
..."
-
Dette kabeltype burde kunne formidle alle OAM:
http://en.wikipedia.org/wiki/Single-wire_transmission_line#E-Line
Citat: "...
a more general mode has recently been discovered and demonstrated which
does not have this limitation. "E-Line" is similar to Goubau-Lines in
its use of launching horns to couple to and from a radially symmetric
wave propagating in the space around a single conductor but different in
that it can operate on insulation-free conductors, including those that
are polished and completely unfeatured
...
Contrary to Goubau's assertions, it has been shown both possible and
practical to launch a surface wave on an uninsulated conductor without
special conditioning and without reducing the wave velocity, while still
using launches of practical size. In addition, conductors much larger
than those used by Goubau have been shown to be completely adequate.
Of particular practical value, common uninsulated single or multistrand
overhead power conductor may be used to support very low attenuation
propagation over the *entire* *frequency* *range* from below 200 MHz to
above 10 GHz while employing a launch device of only 15-20 cm in
diameter. This makes available the worldwide installed base of overhead
powerline for very high rate information transport.
...
The effects of line taps, bends, insulators and other impairments
normally found on power distribution systems have proven to be
predictable and managable.
..."
TESLA'S BIG MISTAKE?
William Beaty
http://www.amasci.com/tesla/tmistk.html
Citat: "...
Note that this is a SINGLE WIRE transmission line!
...
It turns out that you can send microwave or UHF signals along a *single*
wire as long as that wire is coated with a dielectric [Nej, ikke
nødvendig - se E-line]. To do this, you start out with a normal coaxial
cable. You strip the shield from a central section, then solder on a
pair of large, cone-shaped copper horns which attach to the coax shield
at either end of the coax cable. The dielectric-coated single wire
extends between the ends of the coax. Sort of like this
...
The metal cones act as "wave launchers" or "wave catchers".
..."
A History of Surface-Wave Technology:
http://web.archive.org/web/20050130162516/rubytron.com/pdf/RadWire_history.pdf
Citat: "...The single-wire G-line could transmit microwave RF power with
less loss than coaxial cable..."
http://www.corridor.biz/
Citat: "...The PowerCorridortm MOBILE system provides extremely cost
effective hole filling and coverage extension with greatly simplified
permitting and installation - all at CAPEX costs that are a fraction of
alternative solutions. The system supports all wireless systems
including 2G, 3G and WiFi..."
-
Se hornet til venstre:
PowerCorridor(tm) MOBILE:
http://www.corridor.biz/Technology.html
Citat: "...
Applications of this discovery easily and inexpensively provides very
efficient, linear and broadband transport of information-carrying
spectrum anywhere in the 50MHz - 20Ghz frequency range using existing
infrastrure.
..."
Broadband over Power Lines:
http://www.rac.ca/en/amateur-radio/regulatory/threats/power-line-communications.php#California%20firm
Citat: "... Surfacewave transmission on an insulated single conductor
was first discovered and presented by Goubau 1 in the early 1950's and
known as G-Line 2 after the inventor. The characteristics of surfacewave
propagation, when used with a variety of dielectric types, thickness
and specially prepared conductors, have been taught and available in
reference texts for many years 3. Though not widely utilized in
practice, the mode can exhibit extremely low radiation and transmission
losses from VHF into the microwave regions..."
-
Endnu et par løsninger med lave tab:
Er vist først interessant ved 3GHz eller højere - ukendt tab/længde:
Loading Image...
-
Mon man kan lave SWR-måler som måler for hver enkelt OAM? ;-) Kunne det
anvendes til TDR på E-lines/G-lines? (OAM-TDR ;-) ):
http://en.wikipedia.org/wiki/Time-domain_reflectometer
http://en.wikipedia.org/wiki/Time-domain_reflectometry
Glenn/OZ1HFT
Hvem kan forklare mig forskellen mellem cirkular polarisation - og
elektromagnetisk(f.eks. lys, radiobølger...) orbital angular momentum
(OAM)-bølger? - eller henvise til dansk eller engelsk litteratur om det?
Bispørgsmål - er der en relation mellem kvantemekanisk spin og OAM?
Hvis det virkelig er rigtigt, betyder det at man bl.a. kan lave nye?:
* bedre optiske mikroskoper
* finde materialer som fungerer ligesom polariserende stoffer a la
LCD-polarisationsfiltre, men til OAM.
* som de skriver i New Journal of Physics-artiklen - større effektiv
udnyttet båndbredde - jeg kan dog ikke se hvordan båndbredde kan
bibeholdes for varierende modulation af OAM-kanaler.
Nogen burde gå forrest og teste om det virker?
* Hvorfor kan en opklippet og passende bøjet reflektor (se New Journal
of Physics-artiklen, "Figure A4. The helicoidal parabolic antenna") have
en sådan OAM virkning?
* Er vandret/lodret/venstre/højre-drejede polarisationer ortogonale på
OAM-bølger? (måske varierer effekten/fænomenet med afstanden?)
* Kan en yagi/helical-antenne laves om til en OAM-antenne ved at klippe
og bøje en cirkulær reflektor? Ligesom parabolreflektoren i New Journal
of Physics-artiklen?
* Kan en yagi/helical-antenne laves om til en OAM-antenne uden at pille
ved reflektoren?
* Findes der naturlige radiobølge objekt passeringer/reflekteringer, som
konverterer en traditionel radiobølge til en eller anden OAM-radiobølge?
* Radar burde i den grad kunne få gavn af OAM-bølger?
* kan man sende og identificere OAM-superpositioner? F.eks. burde man
kunne skelne mellem 3-OAM, 5-OAM og 7-OAM, uanset om de reflekteres
eller lægges sammen med andre?
* Kan (-1_OAM) + (+1_OAM) ophæve hinanden?
* kan to ens antenner som sender samme OAM-superposition, "lægges"
sammen eller vil de interferere anderledes end traditionelle polarisationer?
Benytter "spatial_multiplexing" i virkeligheden OAM?:
http://en.wikipedia.org/wiki/Spatial_multiplexing
Functions of MIMO:
http://en.wikipedia.org/wiki/MIMO#Functions_of_MIMO
Citat: "…
In spatial multiplexing, a high rate signal is split into multiple lower
rate streams and each stream is transmitted from a different transmit
antenna in the same frequency channel. If these signals arrive at the
receiver antenna array with sufficiently different spatial signatures,
the receiver can separate these streams into (almost) parallel channels.
Spatial multiplexing is a very powerful technique for increasing channel
capacity at higher signal-to-noise ratios (SNR). The maximum number of
spatial streams is limited by the lesser of the number of antennas at
the transmitter or receiver.
…"
-
Akustiske bølger med OAM-lignende egenskab i faststof eller måske også i
væske og gas (luft)?:
* Har akustiske bølger (f.eks. lydbølger) også mulighed for
"OAM"-lignende-bølger? Bruger flagermus dem (uden at vide det)? Sonar
kan i så fald forbedres?
* Kan visse tryk/seismiske/jordskælvsbølger benytte "OAM"-lignende-bølger?
* Det kan anvendes til at afdække mineral og olie/gas-forekomster bedre?
-
Hvad med andre bølgetyper? Findes de også i "OAM"-lignende-bølger?
Kan graviationsbølger f.eks. lettere afdækkes hvis de modtages opløst i
OAM-"polariseringer"?
-
Mar 7, 2012, Physicists put a new twist on radio:
http://physicsworld.com/cws/article/news/48869
Citat: "...
Physicists have known for many years that a beam of light can be twisted
so that its wavefront rotates around its direction of propagation in a
spiral shape. The twisting is achieved by controlling the orbital
angular momentum of the light. This property is associated with the
shape of a light beam's wavefront – the imaginary line or plane joining
the points on a wave that have the same phase.
The orbital angular momentum should not be confused with the more
familiar spin angular momentum of light, which is associated with a
wave's polarization or direction of oscillation.
...
[Jeg kunne godt tænke mig en demonstration med 4 eller 8 OAM-kanaler -
to er ikke nok - måske er det i virkeligheden de 2 ortogonale
venstre/højre-drejede polarisationskanaler de sender og modtager?: ]
A specially adapted satellite-dish-style antenna on the lighthouse on St
George's Island was used to create radio waves with a frequency of 2.4
GHz and an orbital angular momentum of 1 – the latter meaning that the
wavefront is rotated 360° in the space of one wavelength. A standard
"Yagi" antenna was also used to send waves of the same frequency but
without orbital angular momentum across the same stretch of lagoon.
...
[ Det tyder på, at det IKKE er 2 ortogonale venstre/højre-drejede
polarisationskanaler?: ]
By varying the distance between the two receiving antennas on the
balcony of the Doge's Palace, the researchers were able to tune in to
either the twisted or the untwisted beam. This proves, they say, that
they were able to transmit two channels simultaneously using just a
single frequency.
...
[ En af gulerødderne - hvis det er rigtigt: ]
it means in principle being able to create an infinite number of
channels in a given bandwidth, with each channel encoded using a
different orbital angular momentum.
..."
1 marts 2012, Encoding many channels on the same frequency through radio
vorticity: first experimental test:
http://iopscience.iop.org/1367-2630/14/3/033001/article
-
Light orbital angular momentum:
http://en.wikipedia.org/wiki/Light_orbital_angular_momentum
Circular polarization:
http://en.wikipedia.org/wiki/Circular_polarization
Spin (physics):
http://en.wikipedia.org/wiki/Spin_%28physics%29
Citat: "...
Standard model of particle physics; hence bosons are also called force
carriers. These bosons have s=1.
...
Theory predicts the existence of two bosons whose s differs from 1. The
force carrier for gravity is the hypothetical graviton; theory suggests
that it has s = 2. The Higgs mechanism predicts that elementary
particles acquire nonzero rest mass by exchanging hypothetical Higgs
bosons with an all-pervasive Higgs field. Theory predicts that the Higgs
boson has s = 0. If so, it would be the only elementary particle for
which this is the case.
..."
Photon:
http://en.wikipedia.org/wiki/Photon
Citat: "...
Spin 1
...
The photon is massless,[Note 2] has no electric charge,[12] and is
stable. A photon has two possible polarization states and is described
by exactly three continuous parameters: the components of its wave
vector, which determine its wavelength lambda and its direction of
propagation.
...
The photon also carries spin angular momentum that does not depend on
its frequency.[17] The magnitude of its spin is \scriptstyle{\sqrt{2}
\hbar} and the component measured along its direction of motion, its
helicity, must be +-h. These two possible helicities, called
right-handed and left-handed, correspond to the two possible circular
polarization states of the photon.[18]
..."
-
Dette kabeltype burde kunne formidle alle OAM:
http://en.wikipedia.org/wiki/Single-wire_transmission_line#E-Line
Citat: "...
a more general mode has recently been discovered and demonstrated which
does not have this limitation. "E-Line" is similar to Goubau-Lines in
its use of launching horns to couple to and from a radially symmetric
wave propagating in the space around a single conductor but different in
that it can operate on insulation-free conductors, including those that
are polished and completely unfeatured
...
Contrary to Goubau's assertions, it has been shown both possible and
practical to launch a surface wave on an uninsulated conductor without
special conditioning and without reducing the wave velocity, while still
using launches of practical size. In addition, conductors much larger
than those used by Goubau have been shown to be completely adequate.
Of particular practical value, common uninsulated single or multistrand
overhead power conductor may be used to support very low attenuation
propagation over the *entire* *frequency* *range* from below 200 MHz to
above 10 GHz while employing a launch device of only 15-20 cm in
diameter. This makes available the worldwide installed base of overhead
powerline for very high rate information transport.
...
The effects of line taps, bends, insulators and other impairments
normally found on power distribution systems have proven to be
predictable and managable.
..."
TESLA'S BIG MISTAKE?
William Beaty
http://www.amasci.com/tesla/tmistk.html
Citat: "...
Note that this is a SINGLE WIRE transmission line!
...
It turns out that you can send microwave or UHF signals along a *single*
wire as long as that wire is coated with a dielectric [Nej, ikke
nødvendig - se E-line]. To do this, you start out with a normal coaxial
cable. You strip the shield from a central section, then solder on a
pair of large, cone-shaped copper horns which attach to the coax shield
at either end of the coax cable. The dielectric-coated single wire
extends between the ends of the coax. Sort of like this
...
The metal cones act as "wave launchers" or "wave catchers".
..."
A History of Surface-Wave Technology:
http://web.archive.org/web/20050130162516/rubytron.com/pdf/RadWire_history.pdf
Citat: "...The single-wire G-line could transmit microwave RF power with
less loss than coaxial cable..."
http://www.corridor.biz/
Citat: "...The PowerCorridortm MOBILE system provides extremely cost
effective hole filling and coverage extension with greatly simplified
permitting and installation - all at CAPEX costs that are a fraction of
alternative solutions. The system supports all wireless systems
including 2G, 3G and WiFi..."
-
Se hornet til venstre:
PowerCorridor(tm) MOBILE:
http://www.corridor.biz/Technology.html
Citat: "...
Applications of this discovery easily and inexpensively provides very
efficient, linear and broadband transport of information-carrying
spectrum anywhere in the 50MHz - 20Ghz frequency range using existing
infrastrure.
..."
Broadband over Power Lines:
http://www.rac.ca/en/amateur-radio/regulatory/threats/power-line-communications.php#California%20firm
Citat: "... Surfacewave transmission on an insulated single conductor
was first discovered and presented by Goubau 1 in the early 1950's and
known as G-Line 2 after the inventor. The characteristics of surfacewave
propagation, when used with a variety of dielectric types, thickness
and specially prepared conductors, have been taught and available in
reference texts for many years 3. Though not widely utilized in
practice, the mode can exhibit extremely low radiation and transmission
losses from VHF into the microwave regions..."
-
Endnu et par løsninger med lave tab:
Er vist først interessant ved 3GHz eller højere - ukendt tab/længde:
Loading Image...
-
Mon man kan lave SWR-måler som måler for hver enkelt OAM? ;-) Kunne det
anvendes til TDR på E-lines/G-lines? (OAM-TDR ;-) ):
http://en.wikipedia.org/wiki/Time-domain_reflectometer
http://en.wikipedia.org/wiki/Time-domain_reflectometry
Glenn/OZ1HFT