Lightweight woven helical antenna could replace field-deployed dishes(newatlas.com)
newatlas.com
Lightweight woven helical antenna could replace field-deployed dishes
https://newatlas.com/telecommunications/woven-helical-antenna/
76 comments
This guy recently made a neat roll-up antenna for 2m using "faraday cloth"
https://www.youtube.com/watch?v=X7K6DNLD9Wo
https://www.youtube.com/watch?v=X7K6DNLD9Wo
This guy has been making fabric antennas for a few years and selling them cheap on ebay:
https://www.ebay.co.uk/itm/204232411345
He also makes flatpack helical antennas: https://www.ebay.co.uk/itm/196095158881
I think everyone from hollywood to big corporate companies have been buying his backyard inventions. He should feel really proud getting in there before the academics, youtubers, and opportunists jump on board! I bought this set back in 2019 and have had some really nice chats with the guy.
He also makes flatpack helical antennas: https://www.ebay.co.uk/itm/196095158881
I think everyone from hollywood to big corporate companies have been buying his backyard inventions. He should feel really proud getting in there before the academics, youtubers, and opportunists jump on board! I bought this set back in 2019 and have had some really nice chats with the guy.
Just to add, he writes up on his stuff too:
He made an SBand antenna out of a Beachball: https://dalybulge.blogspot.com/2023/09/diy-gatr-ball-antenna...
Before that a Fabric Parabolic Antenna: https://dalybulge.blogspot.com/2022/11/updates-on-portable-p...
Explaining how he did the design: https://dalybulge.blogspot.com/2022/10/parabola-design.html
He made an SBand antenna out of a Beachball: https://dalybulge.blogspot.com/2023/09/diy-gatr-ball-antenna...
Before that a Fabric Parabolic Antenna: https://dalybulge.blogspot.com/2022/11/updates-on-portable-p...
Explaining how he did the design: https://dalybulge.blogspot.com/2022/10/parabola-design.html
Great find - thanks for sharing!
I once threw a weight with a transformer wire and some string attached to it over a high tree branch in my yard to see if it would make a decent antenna for my SDR, it worked!
It was an extremely inexpensive ~5m antenna
My Lawyer says not to tell you a spud gun can heave a line a good height/distance if you want to make a folded dipole antenna using an old growth fir tree.
Just tie your line through a hole in a soup can and put it over the muzzle before firing a spud.
Just tie your line through a hole in a soup can and put it over the muzzle before firing a spud.
That's actually a really common lightweight SOTA[1] antenna.
[1] https://www.sota.org.uk/
[1] https://www.sota.org.uk/
I'm getting into a new hobby: amateur radio astronomy.
From what I understand you need an dish with d > 1m to pick up hydrogen line emission well.
I'd be interested to know if I can just build a wide wire helix like this instead of investing in a big dish. It'd have to look nice and be weather-proof to be wife-approved though.
From what I understand you need an dish with d > 1m to pick up hydrogen line emission well.
I'd be interested to know if I can just build a wide wire helix like this instead of investing in a big dish. It'd have to look nice and be weather-proof to be wife-approved though.
To get sensitivity you actually need collection area.
Fair point. I’m trying all kinds of backflips to avoid buying a huge dish
I have a similar interest. One way to avoid the large antennas is to have multiple separated small antennas - like the VLA [1] - using an SDR receiver like Kraken [2]
[1] https://www.vla.nrao.edu/ [2] https://www.crowdsupply.com/krakenrf/krakensdr
[1] https://www.vla.nrao.edu/ [2] https://www.crowdsupply.com/krakenrf/krakensdr
That is so cool. I’d call mine the Very Small Array.
I was always under the impression that it’s super hard to pull off interferometery due to precise positioning and timing requirements, but looks like the Kraken multi-antenna you linked has that figured out in a simple way.
I was always under the impression that it’s super hard to pull off interferometery due to precise positioning and timing requirements, but looks like the Kraken multi-antenna you linked has that figured out in a simple way.
I never done sth like this but you can lock the clocks of each of the samplers I guess. Simplest solution might be using a single source clock and distributing it to each board with equal length of cables. You can calibrate the lenght of the cable precisely if you have access to a pulse generator and a scope. Though, alternative would be shifting the sample times in post-processing the data by searching for a high correlation. I believe both are used in practice.
There are other SDR receivers that have external clock inputs. The Kraken does that for you because it is a single unit. Of course there is likely a limit to how long the coax to the antennas can be. Just a guess - for an amateur rig I would think 30 to 60 ft antenna separation would be impressive resolution. Certainly better than buying a 60 ft dish;)
One can always use clock repraters or a reclocking with a new PLL in the middle if the cable length gets too long and caused ISI (inter-symbol-interference). I don't think 30 ft requires this. At 60ft you might need it though it depends on the clock frequency. If the syncronization is done with low frequency clock (10 - 25 MHz or so) you don't need any of that. 60ft cable won't have too strong of an attenuation at those frequencies. GHz rate clock would be a problem.
can we not now use fiberoptic cables to provide a common timestamp signal well above the shannon limit of the emmission lines that would need to be reassembled
Another interesting possibility is to use GPS for a clock. [1] Apparently 1 microsecond accuracy. Maybe useful if you want to make the distance really far. Someone has an article [2] Would be cool if you could pool the resources of multiple amateur rigs over a great distance in ad hoc antenna arrays.
[1] https://digitaldisplay.com/network-clock/master-clock/gps-vs....
[2]https://destevez.net/2022/03/timing-sdr-recordings-with-gps/
[1] https://digitaldisplay.com/network-clock/master-clock/gps-vs....
[2]https://destevez.net/2022/03/timing-sdr-recordings-with-gps/
Yeah GPS is a good tool to sychronize over very long distances. Locally locked clocks might still be better for an array not far away from each other if done properly. GPS might be easier to implement for amateurs though.
Imagine every amateur radio astronomer pointing their dishes at the same thing. If they all upload their data with accurate enough GPS position & timing, it could probably be used.
We just need a standard file format that incorporates the thing being observed and some GPS time sync info (or other time sync source). Anything else? I'm game.
I think this would be amazing to ttack movements but the combined images would be extremely noisy wouldn't it?
Short answer is: no. The long answer is: Speed of light on glass is not so different than electromagnetic signal speed in copper, approximately 0.66C. Considering clock sources output electrical signals, using a coax cable instead of fibre optic has several advantages: simpler signal chain means lower delay, and avoiding highly noisy optical-electrical conversion means less jitter.
Fun fact: RF signals in air travel faster than light in glass fibre (0.8C instead of 0.66C).
Fun fact: RF signals in air travel faster than light in glass fibre (0.8C instead of 0.66C).
A belated Thank You! for your excelent reply.
This is a very cool invention that could have many applications. It reminds me of the origami-inspired robots that can fold and unfold themselves to perform different tasks. I wonder how durable and reliable the antenna is, and how easy it is to deploy and control. It would be interesting to see some experimental results and comparisons with conventional antennas.
Astrophysical jets produce helically and circularly-polarized emissions, too FWIU.
Presumably helical jets reach earth coherently over such distances because of the stability of helical signals.
1. Could a space agency harvest energy from a (helically and/or circularly-polarised) natural jet, for deep space and/or local system exploration? Can a spacecraft pull against a jet for relativistic motion?
2. Is helical the best way to beam power wirelessly; without heating columns of atmospheric water in the collapsing jet stream?
3. Is there a (hydrodynamic) theory of superfluid quantum gravity that better describes the apparent vorticity and curl of such signals and their effects?
Presumably helical jets reach earth coherently over such distances because of the stability of helical signals.
1. Could a space agency harvest energy from a (helically and/or circularly-polarised) natural jet, for deep space and/or local system exploration? Can a spacecraft pull against a jet for relativistic motion?
2. Is helical the best way to beam power wirelessly; without heating columns of atmospheric water in the collapsing jet stream?
3. Is there a (hydrodynamic) theory of superfluid quantum gravity that better describes the apparent vorticity and curl of such signals and their effects?
> Presumably helical jets reach earth coherently over such distances because of the stability of helical signals.
I don't think this is correct.
1. Sure, but I doubt they're energetic enough to power a spacecraft. I don't think you can "pull" against radiation.
2. Not really. Atmospheric gasses are going to be aligned too randomly for polarization to matter much. Circular polarization can be trivially decomposed into linear polarization (with a 90° phase offset) so it can still interact as such.
3. Above my paygrade, but "superfluid quantum gravity" sounds like it's likely be firmly in the theoretical realm of physics. Maybe superfluid vacuum theory may be what you have in mind?
https://en.wikipedia.org/wiki/Superfluid_vacuum_theory
I don't think this is correct.
1. Sure, but I doubt they're energetic enough to power a spacecraft. I don't think you can "pull" against radiation.
2. Not really. Atmospheric gasses are going to be aligned too randomly for polarization to matter much. Circular polarization can be trivially decomposed into linear polarization (with a 90° phase offset) so it can still interact as such.
3. Above my paygrade, but "superfluid quantum gravity" sounds like it's likely be firmly in the theoretical realm of physics. Maybe superfluid vacuum theory may be what you have in mind?
https://en.wikipedia.org/wiki/Superfluid_vacuum_theory
1.
/? energy harvesting (and PV and TPV)
/? inverse tractor beam https://www.google.com/search?q=inverse+tractor+beam
2. Perhaps helical is advantageous over distance (and through plasma). Given efficiency of a power transmission channel, what is the estimated loss due to scattering / heating intermediate mass over what volume of atmosphere.
3. Mass warps spacetime (in Lorentzian GR). Plasma have nonuniform mass. Plasma are apparently fluidic. Fluidic nonuniform plasma mass warps spacetime probably fluidically.
There are various conjectures about quantum n-body gravity, which GR does not solve for. Recently, many additional solutions to [perpetual] non-quantum n-body gravity were posted. https://news.ycombinator.com/item?id=37960035
To model a path of [a quasar jet] through such turbulence as empty space, curl and viscosity very probably matter.
Is empty space empty? The CMB Cosmological Microwave Background shows nonuniform distribution of mass/energy in the observable universe. Due to Dirac (before "Dirac sea" and e.g. Godel's Dust solutions), many have attempted to estimate where dark matter must be; though there are no confirmations of the existence of dark matter which is hypothesized to explanation discrepancies between predicted gravitational force distributions and also expansion constants like the Hubble constant.
A sufficient Superfluid Quantum Relativity must predict the behavior of particles in superfluids like Bose-Einstein condensates and superconductors, and SHOULD or MUST also predict n-body gravity.
Electrons appear to behave fluidically in superconductors.
Photons / Polaritons appear to behave fluidically in superfluids; "liquid light"
"Room-temperature superfluidity in a polariton condensate" (2017) https://www.nature.com/articles/nphys4147
https://news.ycombinator.com/item?id=38871054
https://news.ycombinator.com/item?id=38785433
https://news.ycombinator.com/item?id=38500760 :
>>> "Gravity as a fluid dynamic phenomenon in a superfluid quantum space. Fluid quantum gravity and relativity." (2015) https://hal.science/hal-01248015/ :
>>> [...] Vorticity is interpreted as spin (a particle's internal motion). Due to non-zero, positive viscosity of the SQS, and to Bernoulli pressure, these vortices attract the surrounding quanta, pressure decreases and the consequent incoming flow of quanta lets arise a gravitational potential. This is called superfluid quantum gravity
And in this superfluid quantum gravity, there is no dark matter. It's more like a "Dirac sea" of quantum foam with pressure FWIU; and does this correspond to black hole topologies of particle affect.
/? energy harvesting (and PV and TPV)
/? inverse tractor beam https://www.google.com/search?q=inverse+tractor+beam
2. Perhaps helical is advantageous over distance (and through plasma). Given efficiency of a power transmission channel, what is the estimated loss due to scattering / heating intermediate mass over what volume of atmosphere.
3. Mass warps spacetime (in Lorentzian GR). Plasma have nonuniform mass. Plasma are apparently fluidic. Fluidic nonuniform plasma mass warps spacetime probably fluidically.
There are various conjectures about quantum n-body gravity, which GR does not solve for. Recently, many additional solutions to [perpetual] non-quantum n-body gravity were posted. https://news.ycombinator.com/item?id=37960035
To model a path of [a quasar jet] through such turbulence as empty space, curl and viscosity very probably matter.
Is empty space empty? The CMB Cosmological Microwave Background shows nonuniform distribution of mass/energy in the observable universe. Due to Dirac (before "Dirac sea" and e.g. Godel's Dust solutions), many have attempted to estimate where dark matter must be; though there are no confirmations of the existence of dark matter which is hypothesized to explanation discrepancies between predicted gravitational force distributions and also expansion constants like the Hubble constant.
A sufficient Superfluid Quantum Relativity must predict the behavior of particles in superfluids like Bose-Einstein condensates and superconductors, and SHOULD or MUST also predict n-body gravity.
Electrons appear to behave fluidically in superconductors.
Photons / Polaritons appear to behave fluidically in superfluids; "liquid light"
"Room-temperature superfluidity in a polariton condensate" (2017) https://www.nature.com/articles/nphys4147
https://news.ycombinator.com/item?id=38871054
https://news.ycombinator.com/item?id=38785433
https://news.ycombinator.com/item?id=38500760 :
>>> "Gravity as a fluid dynamic phenomenon in a superfluid quantum space. Fluid quantum gravity and relativity." (2015) https://hal.science/hal-01248015/ :
>>> [...] Vorticity is interpreted as spin (a particle's internal motion). Due to non-zero, positive viscosity of the SQS, and to Bernoulli pressure, these vortices attract the surrounding quanta, pressure decreases and the consequent incoming flow of quanta lets arise a gravitational potential. This is called superfluid quantum gravity
And in this superfluid quantum gravity, there is no dark matter. It's more like a "Dirac sea" of quantum foam with pressure FWIU; and does this correspond to black hole topologies of particle affect.
/? collinearity in a helical beam:
https://www.google.com/search?q=collinearity+in+a+helical+be...
"Collinear superposition of multiple helical beams generated by a single azimuthally modulated phase-only element" (2005) https://opg.optica.org/ol/abstract.cfm?uri=ol-30-24-3266 https://scholar.google.com/scholar?cites=4433448650775789641...
OAM: Orbital Angular Momentum of Light: https://en.wikipedia.org/wiki/Orbital_angular_momentum_of_li...
"Universal orbital angular momentum spectrum analyzer for beams" (2020) https://link.springer.com/article/10.1186/s43074-020-00019-5 https://scholar.google.com/scholar?cites=7156827987133110450... :
"Approaching the Fundamental Limit of Orbital Angular Momentum Multiplexing Through a Hologram Metasurface" (2022) https://arxiv.org/abs/2106.15120
> This limit considers only one type of polar- ization, and it should be doubled if dual polarizations are adopted. If more plane-wave modes beyond this limit are added, they will not be distinguishable or angularly re- solved. Evanescent modes are required to support the expanded angular spectrum, which, however, are not suitable for far-field communication.
"Phase Singularities to Polarization Singularities" (2020) https://www.hindawi.com/journals/ijo/2020/2812803/ :
> The phase gradient in a phase singularity and azimuth gradient in a polarization singularity circulate around the respective singularities.
"Engineering phase and polarization singularity sheets" (2021) https://www.nature.com/articles/s41467-021-24493-y :
> Optical phase singularities are zeros of a scalar light field. The most systematically studied class of singular fields is vortices: beams with helical wavefronts and a linear (1D) singularity along the optical axis. Beyond these common and stable 1D topologies, we show that a broader family of zero-dimensional (point) and two-dimensional (sheet) singularities can be engineered. We realize sheet singularities by maximizing the field phase gradient at the desired positions. These sheets, owning to their precise alignment requirements, would otherwise only be observed in rare scenarios with high symmetry. Furthermore, by applying an analogous procedure to the full vectorial electric field, we can engineer paraxial transverse polarization singularity sheets. As validation, we experimentally realize phase and polarization singularity sheets with heart-shaped cross-sections using metasurfaces. Singularity engineering of the dark enables new degrees of freedom for light-matter interaction and can inspire similar field topologies beyond optics, from electron beams to acoustics.
"Collinear superposition of multiple helical beams generated by a single azimuthally modulated phase-only element" (2005) https://opg.optica.org/ol/abstract.cfm?uri=ol-30-24-3266 https://scholar.google.com/scholar?cites=4433448650775789641...
OAM: Orbital Angular Momentum of Light: https://en.wikipedia.org/wiki/Orbital_angular_momentum_of_li...
"Universal orbital angular momentum spectrum analyzer for beams" (2020) https://link.springer.com/article/10.1186/s43074-020-00019-5 https://scholar.google.com/scholar?cites=7156827987133110450... :
"Approaching the Fundamental Limit of Orbital Angular Momentum Multiplexing Through a Hologram Metasurface" (2022) https://arxiv.org/abs/2106.15120
> This limit considers only one type of polar- ization, and it should be doubled if dual polarizations are adopted. If more plane-wave modes beyond this limit are added, they will not be distinguishable or angularly re- solved. Evanescent modes are required to support the expanded angular spectrum, which, however, are not suitable for far-field communication.
"Phase Singularities to Polarization Singularities" (2020) https://www.hindawi.com/journals/ijo/2020/2812803/ :
> The phase gradient in a phase singularity and azimuth gradient in a polarization singularity circulate around the respective singularities.
"Engineering phase and polarization singularity sheets" (2021) https://www.nature.com/articles/s41467-021-24493-y :
> Optical phase singularities are zeros of a scalar light field. The most systematically studied class of singular fields is vortices: beams with helical wavefronts and a linear (1D) singularity along the optical axis. Beyond these common and stable 1D topologies, we show that a broader family of zero-dimensional (point) and two-dimensional (sheet) singularities can be engineered. We realize sheet singularities by maximizing the field phase gradient at the desired positions. These sheets, owning to their precise alignment requirements, would otherwise only be observed in rare scenarios with high symmetry. Furthermore, by applying an analogous procedure to the full vectorial electric field, we can engineer paraxial transverse polarization singularity sheets. As validation, we experimentally realize phase and polarization singularity sheets with heart-shaped cross-sections using metasurfaces. Singularity engineering of the dark enables new degrees of freedom for light-matter interaction and can inspire similar field topologies beyond optics, from electron beams to acoustics.
That looks very cool!
Antenna science is a deep pond. I worked for a defense contractor that did microwave stuff, and the antenna scientists were a breed unto themselves (frequently "odd").
Antenna science is a deep pond. I worked for a defense contractor that did microwave stuff, and the antenna scientists were a breed unto themselves (frequently "odd").
Is this still able to be directed/pointed in the same way as a satellite dish? Very cool if so, the article says that it can be used in lieu of satellite dishes, but I'm wondering if there's any downsides due to the geometry of the solution.
Yes, QFH antennas are directional. But the other benefit is they're circularly polarized which is a benefit in satellite communication because you don't know how the satellite is oriented in space.
The innovation here is the antenna that's normally static and somewhat fragile is now collapsible and part of the woven structure. Really neat idea.
https://www.instructables.com/NOAA-Satellite-Signals-with-a-...
The innovation here is the antenna that's normally static and somewhat fragile is now collapsible and part of the woven structure. Really neat idea.
https://www.instructables.com/NOAA-Satellite-Signals-with-a-...
In many cases, the geometry of antennae matter. I would worry that a flexible antenna like this might be bent or stretched enough to degrade performance. Am I right?
It's just strips of thin metal and thin 'plastic', insanely cheap to produce and replace if they get damaged.
Dishes are also fairly easy to damage, especially if they're torn down and moved.
That said, what's shown isn't 100% of the antennae, you need a ground plane disc that the helix is attached to and acts as a reflector.
Dishes are also fairly easy to damage, especially if they're torn down and moved.
That said, what's shown isn't 100% of the antennae, you need a ground plane disc that the helix is attached to and acts as a reflector.
Ground planes are not really necessary for helix antennae IMHO.
Put it in a plastic cylinder to protect it, with an easily removable lid and you'll fix that issue for many situations.
Unless there is something weird about plastic that impacts the signal, it might even be able to stay in the container when running.
Might be as simple as carrying around a device about the size of a Pringles can. Will be interesting space to watch, ass this could truly disrupt many things. Attached to a drone or ballon, and the possibilities multiply versus a static location.
Side note: I wonder if future wifi hubs will be cylindrical. Much better than the spiders today.
Unless there is something weird about plastic that impacts the signal, it might even be able to stay in the container when running.
Might be as simple as carrying around a device about the size of a Pringles can. Will be interesting space to watch, ass this could truly disrupt many things. Attached to a drone or ballon, and the possibilities multiply versus a static location.
Side note: I wonder if future wifi hubs will be cylindrical. Much better than the spiders today.
I think the “bi-stable” part of this somewhat addresses this, it’s designed to snap into either a tall or flat configuration, so it should at least be harder to distort than a freely moving version would be.
Yes.
Since the frequency can be adjusted based on the amount its stretched - such that in the 'short-squshed state its better for 'ground' users - and stretched for satellite comms -- could one of these be 'Funnel-shaped' so that you have a wide, but squished 'ground'section - and then it funnels to a stretched out length for satts?
Or can you only have one frequency per form?
Or can you only have one frequency per form?
It's not the frequency of the antenna that changes, it's the directivity of the emitted power. The resonant frequency is determined by the length of the metallic strips of the helix which determines how thick and tall the helix is. The angle of the helix when the strip lengths are fixed is what determines the directivity pattern, which is what they are adjusting here by squashing it down.
If you tried to design an antenna that was good at both directions, you'd end up with an omnidirectional antenna which is exactly what the extended helical does. If you don't know where the receiver is, you build an omnidirectional antenna that will send power out in all directions. When you do know where the receiver is, you build a directional antenna that puts most of the power in a specific direction (and make sure the antenna is pointed that way). You can see the polar plots in Figure 8 in the article that shows two different plots, one with a flat shape that puts most power in the horizontal direction with little being directed backwards (extended helix). The next plot shows nearly all the power being directed to 0deg, meaning straight up (squashed helix). The next plots show that at 1.1GHz, the extended helix has a pretty flat gain between -100 and +100deg but the squashed helix has nearly 10dB gain at 0deg. There are other directional antennas that can get better gain at 0deg but they aren't flexible like this design.
I could see this kind of design used for cellular modems mounted on vehicles. If you are within range of a tower, the antenna is in the extended state. If you are out of range, the antenna moves to a flattened state to try to reach a satellite capable of receiving cell communications.
It could also be used in other applications where the extended state and is used to locate a signal but then once it's been detected, the antenna morphs to the flattened state and is pointed at the signal source. Extra gain means you can increase bandwidth of a digital signal.
If you tried to design an antenna that was good at both directions, you'd end up with an omnidirectional antenna which is exactly what the extended helical does. If you don't know where the receiver is, you build an omnidirectional antenna that will send power out in all directions. When you do know where the receiver is, you build a directional antenna that puts most of the power in a specific direction (and make sure the antenna is pointed that way). You can see the polar plots in Figure 8 in the article that shows two different plots, one with a flat shape that puts most power in the horizontal direction with little being directed backwards (extended helix). The next plot shows nearly all the power being directed to 0deg, meaning straight up (squashed helix). The next plots show that at 1.1GHz, the extended helix has a pretty flat gain between -100 and +100deg but the squashed helix has nearly 10dB gain at 0deg. There are other directional antennas that can get better gain at 0deg but they aren't flexible like this design.
I could see this kind of design used for cellular modems mounted on vehicles. If you are within range of a tower, the antenna is in the extended state. If you are out of range, the antenna moves to a flattened state to try to reach a satellite capable of receiving cell communications.
It could also be used in other applications where the extended state and is used to locate a signal but then once it's been detected, the antenna morphs to the flattened state and is pointed at the signal source. Extra gain means you can increase bandwidth of a digital signal.
>>>*"the antenna moves to a flattened state to try to reach a satellite capable of receiving cell communications."
Sounds just like what Starlink is going to need for the direct to cell service they just tested!
But your point of mobile mounting this sounds pretty great, and obvious when its pointed out, actually.
I hope this does good things.
Hopefully its something that anyone can make and doesnt need to pay some high fee to benefit from.
Sounds just like what Starlink is going to need for the direct to cell service they just tested!
But your point of mobile mounting this sounds pretty great, and obvious when its pointed out, actually.
I hope this does good things.
Hopefully its something that anyone can make and doesnt need to pay some high fee to benefit from.
"(Dish antennas) require a lot of power to operate". "Our antenna is lightweight, low-power..."
What does she mean power to operate? When steering the dish with motors? Or is it in some special category for efficiency.
What does she mean power to operate? When steering the dish with motors? Or is it in some special category for efficiency.
My guess is that they're talking about the radiation efficiency -- the strength of signal you get for a unit of power. I would interpret that sentence to mean that communicating with a satellite over a dish antenna will take more power than using this helical antenna in its short state.
https://en.wikipedia.org/wiki/Radiation_efficiency
https://en.wikipedia.org/wiki/Radiation_efficiency
...wonder if you could make something similar to this starting from a slinky? Chop it up into 4 bits, stretch them, give them some diy cladding/enframing of some kind, etc?
Would be interesting to see this antenna modelled in MMANA-GAL
This could be really cool for drone/fpv application.
We already have helical antennas and most fpv is done at a high enough frequency that the antennas fit in your hand. Might be nice for 1.2ghz or lower but even there I can't see it folding down much lower than a VAS crosshair or pepperbox.
A long-range directional base station that automatically tracks the drone (and can switch to omni at short range) would be cool.
As I understand it this new antenna changes frequencies in the collapsed/omni states so you would then need multiple transmitters/antennas on the drone which would be weight prohibitive.
Antenna tracking ground stations and diversity receivers have been around since the early fpv days, although tracking isn't very mainstream because its challenging to set it all up. I'd still prefer my dual antenna / diversity RX setup since it provides some redundancy.
Antenna tracking ground stations and diversity receivers have been around since the early fpv days, although tracking isn't very mainstream because its challenging to set it all up. I'd still prefer my dual antenna / diversity RX setup since it provides some redundancy.
Ahh thanks, I hadn't seen that detail.
I thought the tracking could be mostly automated between GPS (outdoor) and direction finding + dBm (indoor/canyon), but I guess not.
I thought the tracking could be mostly automated between GPS (outdoor) and direction finding + dBm (indoor/canyon), but I guess not.
>"Importantly, that cylinder can be pulled out into a long skinny configuration about one foot tall (305 mm), or pushed down to form a ring about one inch tall by five inches across (25 by 127 mm).
In its long state – and when connected to electronics such as a transceiver, ground plane and battery – the antenna emits a low-power signal in all directions, allowing for radio communications with ground-based team members. In its short state, it sends a high-power signal in a specific direction, allowing for satellite communications.
The frequencies utilized in either state are determined by the exact dimensions of each individual antenna."
Isn't that weird and interesting?
An antenna which can transmit in two distinct "dispersion modes" depending on shape and frequency...
In "wide-dispersion mode" (for lack of a better term), it is a standard transmitting antenna, probably subject to the inverse square law (https://en.wikipedia.org/wiki/Inverse-square_law), that is, not unlike the radio frequency analogue of incandescent light -- as might be emitted from an incandescent light bulb...
In "narrow-dispersion" (AKA "focused" AKA "beam") mode -- it is no longer subject to the inverse square law(!) -- and is not unlike the radio frequency analogue of a laser beam!
What's amazing (to me!) is that apparently (if this article is true!) frequency makes all of the difference between dispersion modes -- relative to size and shape.
In other words, perhaps it is possible to get a laser to act more like an incandescent light soruce if its frequency is changed, and conversely, perhaps it is possible to get an incandescent light source to act more like a laser, again, if its frequency is changed. (Of course, in the latter case, we'd need to start with a single frequency since incandescent/white light is by definition multiple frequencies...).
And perhaps this same effect is possible across all frequencies (RF, infrared, ultraviolet, etc., etc.)...
This antenna/coil design seems very similar to something called a "Caduceus Coil", which I first read about on the now defunct Keelynet BBS/website, a copy of one such file is here: https://www.newphysics.se/archives/keelynet/energy/caduceus....
Related (future) question: Under what conditions, exactly (exceedingly rigorous definition required!) is a coil (AKA "inductor") in a circuit also an antenna -- and conversely, when exactly is an antenna in a circuit also a coil?
The "Hopf Fibration" -- might be related to all of this:
https://www.google.com/search?q=hopf+fibration&tbm=isch
As might the ancient notion of the "Norse World Tree":
https://www.google.com/search?q=norse+world+tree&tbm=isch
Related:
https://www.mail-archive.com/[email protected]/msg31218....
Anyway, a very interesting article!
In its long state – and when connected to electronics such as a transceiver, ground plane and battery – the antenna emits a low-power signal in all directions, allowing for radio communications with ground-based team members. In its short state, it sends a high-power signal in a specific direction, allowing for satellite communications.
The frequencies utilized in either state are determined by the exact dimensions of each individual antenna."
Isn't that weird and interesting?
An antenna which can transmit in two distinct "dispersion modes" depending on shape and frequency...
In "wide-dispersion mode" (for lack of a better term), it is a standard transmitting antenna, probably subject to the inverse square law (https://en.wikipedia.org/wiki/Inverse-square_law), that is, not unlike the radio frequency analogue of incandescent light -- as might be emitted from an incandescent light bulb...
In "narrow-dispersion" (AKA "focused" AKA "beam") mode -- it is no longer subject to the inverse square law(!) -- and is not unlike the radio frequency analogue of a laser beam!
What's amazing (to me!) is that apparently (if this article is true!) frequency makes all of the difference between dispersion modes -- relative to size and shape.
In other words, perhaps it is possible to get a laser to act more like an incandescent light soruce if its frequency is changed, and conversely, perhaps it is possible to get an incandescent light source to act more like a laser, again, if its frequency is changed. (Of course, in the latter case, we'd need to start with a single frequency since incandescent/white light is by definition multiple frequencies...).
And perhaps this same effect is possible across all frequencies (RF, infrared, ultraviolet, etc., etc.)...
This antenna/coil design seems very similar to something called a "Caduceus Coil", which I first read about on the now defunct Keelynet BBS/website, a copy of one such file is here: https://www.newphysics.se/archives/keelynet/energy/caduceus....
Related (future) question: Under what conditions, exactly (exceedingly rigorous definition required!) is a coil (AKA "inductor") in a circuit also an antenna -- and conversely, when exactly is an antenna in a circuit also a coil?
The "Hopf Fibration" -- might be related to all of this:
https://www.google.com/search?q=hopf+fibration&tbm=isch
As might the ancient notion of the "Norse World Tree":
https://www.google.com/search?q=norse+world+tree&tbm=isch
Related:
https://www.mail-archive.com/[email protected]/msg31218....
Anyway, a very interesting article!
The intensity of the beam still falls off by the inverse square law but it covers a cone instead of a pattern like
https://en.wikipedia.org/wiki/Dipole_antenna
https://en.wikipedia.org/wiki/Dipole_antenna
Why does the intensity of the light emitted by an incandescent light bulb fall off with the square of the distance (the inverse square law) -- but the light of a laser beam does not?
?
???
?
???
The light of a laser does diminish at the square of the distance but the cone is very, very narrow. This is because laser light is collimated. The production of laser light occurs in an optical cavity that where uncollimated light is reflected back into the cavity. I would really just be quoting wikipedia so I included the link.
A parabolic antenna also collimates the energy, reducing the size of the cone that the energy is spread over. This allows things like point-to-point communication and narrow-field radio telescopy.
The "power" of a transmitter is the effective radiated power so a transmitter using 1 watt might spread that out over a wide area, but with low power in each direction, or collimate it to a narrow area but with relatively high power in that one direction.
https://en.wikipedia.org/wiki/Collimated_beam
https://en.wikipedia.org/wiki/Optical_cavity
https://en.wikipedia.org/wiki/Parabolic_antenna
https://en.wikipedia.org/wiki/Effective_radiated_power
A parabolic antenna also collimates the energy, reducing the size of the cone that the energy is spread over. This allows things like point-to-point communication and narrow-field radio telescopy.
The "power" of a transmitter is the effective radiated power so a transmitter using 1 watt might spread that out over a wide area, but with low power in each direction, or collimate it to a narrow area but with relatively high power in that one direction.
https://en.wikipedia.org/wiki/Collimated_beam
https://en.wikipedia.org/wiki/Optical_cavity
https://en.wikipedia.org/wiki/Parabolic_antenna
https://en.wikipedia.org/wiki/Effective_radiated_power
Cones are still subject to inverse square. What matters more is that the focal length is much longer (effectively infinite) with a collimated beam -- that is, the (virtual) tip of the cone is very far behind the light generating element. Inverse square only applies at distances from the source much greater than the focal length.
And just to add a little more--
Laser beams at short distances don't fall off inverse square and may even increase in intensity (decrease in spot size) with distance.
But in the end, beam dispersion/the diffraction limit wins and the power density is inverse square.
(I can focus a big light down to a smaller spot; but ultimately the light is going to be spreading out. This can be true for radio, too, with weird things happening close).
Laser beams at short distances don't fall off inverse square and may even increase in intensity (decrease in spot size) with distance.
But in the end, beam dispersion/the diffraction limit wins and the power density is inverse square.
(I can focus a big light down to a smaller spot; but ultimately the light is going to be spreading out. This can be true for radio, too, with weird things happening close).
The laser beam spreads over distance, it's just the cone is really narrow so you have to get far away to notice.
Photons from a laser are generated from amplification in a particular direction, so they point the same way from the beginning.
coherence.
Light from a bulb is not coherent, so it interferes with itself and spreads out.
Light from a bulb is not coherent, so it interferes with itself and spreads out.
OK, so if it is coherence -- then what's the generalized method to make a given EM wavelength or frequency band (light specifically, all EM wavelengths generally) coherent?
That is, in Physics, how would one take an EM wavelength/set of wavelengths/frequency/set of frequencies (or even more broadly speaking, "energy") -- and make it coherent?
That is, in Physics, how would one take an EM wavelength/set of wavelengths/frequency/set of frequencies (or even more broadly speaking, "energy") -- and make it coherent?
The antenna is already coherent because it is driven by a single signal. The lightbulb isn't because individual electrons are being shaken randomly by thermal noise. The laser is coherent because it is taking advantage of stimulated emission which makes the output photons coherent with the environmental field.
https://en.wikipedia.org/wiki/Coherence_(physics)
See https://www.eso.org/sci/facilities/paranal/telescopes/vlti/t...
(I wish I could find a better writeup of the spatial interferometer, it's actually a pretty simple concept and a simple experiment but I've never seen it explained very well, even in print, when I was studying physics.)
https://en.wikipedia.org/wiki/Coherence_(physics)
See https://www.eso.org/sci/facilities/paranal/telescopes/vlti/t...
(I wish I could find a better writeup of the spatial interferometer, it's actually a pretty simple concept and a simple experiment but I've never seen it explained very well, even in print, when I was studying physics.)
>"The antenna is already coherent because it is driven by a single signal.
1) Did you mean laser or antenna?
2) By single signal, did you mean single frequency? (If so, I get it. If not, please elaborate...)
>"The lightbulb isn't because individual electrons are being shaken randomly by thermal noise. The laser is coherent because it is taking advantage of stimulated emission which makes the output photons coherent with the environmental field."
3) If thermal noise is the reason that a lightbulb's light cannot be made coherent -- then could you suggest a method whereby the thermal noise in the lightbulb could be removed such that the light emitted could be made coherent?
4) What do you mean exactly by "environmental field"? (A Google search for that term in the context of Physics -- seems not to yield any results -- but then again I lay no claim to being the best Google searcher out there...)
1) Did you mean laser or antenna?
2) By single signal, did you mean single frequency? (If so, I get it. If not, please elaborate...)
>"The lightbulb isn't because individual electrons are being shaken randomly by thermal noise. The laser is coherent because it is taking advantage of stimulated emission which makes the output photons coherent with the environmental field."
3) If thermal noise is the reason that a lightbulb's light cannot be made coherent -- then could you suggest a method whereby the thermal noise in the lightbulb could be removed such that the light emitted could be made coherent?
4) What do you mean exactly by "environmental field"? (A Google search for that term in the context of Physics -- seems not to yield any results -- but then again I lay no claim to being the best Google searcher out there...)
(1) antenna
(2) the signal of a radio transmitter is (usually) more or less a sine wave that is either modulated by varying the amplitude or the frequency. You could feed the same signal to multiple antennas. For instance in this photo
https://mastodon.social/@UP8/111780254496170231
there is a radio antenna used for emergency responder comms. Note that there are several arrays of antennas stacked on top of each other. If you feed the same signal into an array like that the radiation pattern becomes focused around the horizontal plane so that energy is not thrown into the ground and the sky.
(3) It is the shaking by random vibrations that makes the black body radiation of a light bulb. If you stopped that shaking there wouldn't be any light.
(4) By "environmental field" I mean the electromagnetic field inside the laser that an active molecule or atom inside the laser experiences.
Note if I hooked up 50 antennas to the same oscillator that would be coherent, but if I hooked up 50 antennas to 50 different oscillators that would be incoherent.
Take a look at
https://en.wikipedia.org/wiki/Phased_array
there are two ways to build a phased array. A passive phased array has one transmitter and an collection of phase shifters that delay the signal to create a controlled wavefront. In the first case the emissions of all the antennas are coherent because they come from the same oscillator, in the second case the antennas are coherent because the oscillators are synchronized to a common timebase and controlled by a computer.
Note the "magic" of that kind of phased array is similar to the "magic" of a hologram (they do similar things to wavefronts.) Light other than laser light has a certain amount of coherence though it is a complicated subject, see
https://www.nature.com/articles/s41598-017-06215-x
Note in Figure 10 they show that you can get enough coherence out of an LED to make a hologram. When they use a real laser the picture is really sharp but you see a speckle pattern that's caused by interference of the light with surface roughness. The LED image is blurry but doesn't have the speckle.
(2) the signal of a radio transmitter is (usually) more or less a sine wave that is either modulated by varying the amplitude or the frequency. You could feed the same signal to multiple antennas. For instance in this photo
https://mastodon.social/@UP8/111780254496170231
there is a radio antenna used for emergency responder comms. Note that there are several arrays of antennas stacked on top of each other. If you feed the same signal into an array like that the radiation pattern becomes focused around the horizontal plane so that energy is not thrown into the ground and the sky.
(3) It is the shaking by random vibrations that makes the black body radiation of a light bulb. If you stopped that shaking there wouldn't be any light.
(4) By "environmental field" I mean the electromagnetic field inside the laser that an active molecule or atom inside the laser experiences.
Note if I hooked up 50 antennas to the same oscillator that would be coherent, but if I hooked up 50 antennas to 50 different oscillators that would be incoherent.
Take a look at
https://en.wikipedia.org/wiki/Phased_array
there are two ways to build a phased array. A passive phased array has one transmitter and an collection of phase shifters that delay the signal to create a controlled wavefront. In the first case the emissions of all the antennas are coherent because they come from the same oscillator, in the second case the antennas are coherent because the oscillators are synchronized to a common timebase and controlled by a computer.
Note the "magic" of that kind of phased array is similar to the "magic" of a hologram (they do similar things to wavefronts.) Light other than laser light has a certain amount of coherence though it is a complicated subject, see
https://www.nature.com/articles/s41598-017-06215-x
Note in Figure 10 they show that you can get enough coherence out of an LED to make a hologram. When they use a real laser the picture is really sharp but you see a speckle pattern that's caused by interference of the light with surface roughness. The LED image is blurry but doesn't have the speckle.
Absorb; and then re-emit coherently, accepting conversion losses.
Coherence is not a necessary property of collimated (nondiverging) light (and doesn't cause it to "spread out"). You can produce noncoherent collimated light from any point source using e.g. a parabolic mirror.
> Isn't that weird and interesting?
I think it's very neat! There's calculators online to design your own QFH antennas and they're popular for amateur use to e.g. receive images from weather satellites. And the calculators can tell you that if you make it more squat, it's more directional.
But I don't think anyone had had the idea before to let you vary those parameters by pinning/scissoring it.
I think it's very neat! There's calculators online to design your own QFH antennas and they're popular for amateur use to e.g. receive images from weather satellites. And the calculators can tell you that if you make it more squat, it's more directional.
But I don't think anyone had had the idea before to let you vary those parameters by pinning/scissoring it.
[deleted]
it's just a helical antenna - where are you seeing any reference to phased-array?
[deleted]
You can build a phased array of any kind of antenna... Patch, helical, dish, etc.
The dish antennas I am thinking of use parabolic reflectors.
https://store.am.gallagher.com/am/us/en_US/animal-management...
which has metal fibers woven into a mesh of plastic fibers. Even though the structure is mostly non-metallic I think it gives a better shock than a plain wire. I think I'm going to try making a ham radio antenna using that stuff.