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#2560 by Rodal on 18 May, 2016 13:43
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Yep, can do later this week. Seems I did notice several RL peaks when I first fired up the VNA. Did you order yours?Long day of yardwork and building. Frustum soldered shut. Need only silver epoxy on large base to complete, but small base is 100% done. So, ran another sweep. Pushed VNA to slowest scan and very narrow bandwidth. 63dB return loss and note soldering brought frequency down to abt 2.44 Ghz. Much closer to 2450 modeling target. 10 MHz is close enough. Variation was my hand-building at home. No CNC machining, no lathe, none of the stuff I wish I had. Cut copper by hand. Here's the sweep...time for bed.
Would it be possible to sweep the frustum from 1Ghz - 2.5Ghz? Curious to see that trace and if there are any other modes near. It may be possible to compare that trace with NASA's sweep to identify them.
What are the internal dimensions of Dave's latest truncated cone cavity?
Does it have the same dimensions as the NASA cavity, in order to allow direct comparison of the spectrum? -
#2561 by Monomorphic on 18 May, 2016 13:52
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Yep, can do later this week. Seems I did notice several RL peaks when I first fired up the VNA. Did you order yours?Long day of yardwork and building. Frustum soldered shut. Need only silver epoxy on large base to complete, but small base is 100% done. So, ran another sweep. Pushed VNA to slowest scan and very narrow bandwidth. 63dB return loss and note soldering brought frequency down to abt 2.44 Ghz. Much closer to 2450 modeling target. 10 MHz is close enough. Variation was my hand-building at home. No CNC machining, no lathe, none of the stuff I wish I had. Cut copper by hand. Here's the sweep...time for bed.
Would it be possible to sweep the frustum from 1Ghz - 2.5Ghz? Curious to see that trace and if there are any other modes near. It may be possible to compare that trace with NASA's sweep to identify them.
Yep. Not sure what Ham Radio Outlet's free shipping entails, but hopefully it will be here before the weekend. I'm tempted to just go ahead and order the RF Instruments Spec analyser and get it all over with. I have plenty of copper for one or two more frustums... -
#2562 by Monomorphic on 18 May, 2016 13:57
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Yep, can do later this week. Seems I did notice several RL peaks when I first fired up the VNA. Did you order yours?Long day of yardwork and building. Frustum soldered shut. Need only silver epoxy on large base to complete, but small base is 100% done. So, ran another sweep. Pushed VNA to slowest scan and very narrow bandwidth. 63dB return loss and note soldering brought frequency down to abt 2.44 Ghz. Much closer to 2450 modeling target. 10 MHz is close enough. Variation was my hand-building at home. No CNC machining, no lathe, none of the stuff I wish I had. Cut copper by hand. Here's the sweep...time for bed.
Would it be possible to sweep the frustum from 1Ghz - 2.5Ghz? Curious to see that trace and if there are any other modes near. It may be possible to compare that trace with NASA's sweep to identify them.
What are the internal dimensions of Dave's latest truncated cone cavity?
Does it have the same dimensions as the NASA cavity, in order to allow direct comparison of the spectrum?
Dave's dimensions are different, so direct comparison will not be possible. Traces from different size frustums can be compared - at least in sims i've done - and repeating patterns in the traces can be found.
This is an image where I matched e-field power, not RL, to mode patterns across three different frustum sizes. Albeit, these frustums were simply scaled. If Dave changed the dimension ratios, then it becomes more difficult.
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#2563 by FattyLumpkin on 18 May, 2016 14:41
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Dr. Rodal, the dimensions that I have for of Dave's frustum are: 8" H, 10" LD and 6.25 " SD
Also please see my answer to your question previous page. thanks, FL -
#2564 by Rodal on 18 May, 2016 14:47
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Dr. Rodal, the dimensions that I have for of Dave's frustum are: 8" H, 10" LD and 6.25 " SD
Hi, I need a link to the video you are referring to. In your message link: http://forum.nasaspaceflight.com/index.php?topic=39772.msg1535756#msg1535756 no link is provided to the video.
Also please see my answer to your question previous page. thanks, FL
It is time consuming to look for messages in NSF (even in previous pages, as there are many messages in the same page) because of a very poor search function.
It would save me time if you would provide the video link, and again the time in the video as follows:
video link: .....
time at which Dr. White talks in the video: ...
both in your same message. This would be easiest to me. Thanks. I am multi-tasking with my day-business as I type. -
#2565 by Rodal on 18 May, 2016 14:52
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Dr. Rodal, the dimensions that I have for of Dave's frustum are: 8" H, 10" LD and 6.25 " SD
So Dave's dimensions are smaller than NASA's by 1 inch both in Big D and in Length, but same small diameter, so rfmwguy does not have the same proportional ratio as the NASA frustum (rfmwguy's frustum is truncated sooner than NASA's):
Also please see my answer to your question previous page. thanks, FL
inches
NASA rfmwguy
LENGTH 9 8
BIG D 11 10
SMALL D 6.25 6.25 -
#2566 by Monomorphic on 18 May, 2016 15:10
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Dr. Rodal, the dimensions that I have for of Dave's frustum are: 8" H, 10" LD and 6.25 " SD
So Dave's dimensions are smaller than NASA's by 1 inch both in Big D and in Length, but same small diameter, so rfmwguy does not have the same proportional ratio as the NASA frustum (rfmwguy's frustum is truncated sooner than NASA's):
Also please see my answer to your question previous page. thanks, FL
Not only that, but he also injects RF through middle of the big end. It will probably be easier to compare the real trace to a trace from FEKO. -
#2567 by Rodal on 18 May, 2016 15:18
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So rfmwguy changed the frustum dimensions from those he previously tested? at emdrive wiki experimental http://emdrive.wiki/Experimental_Results he has a longer length than NASA with approximately the same Big D and Small D, for his previous tests.Dr. Rodal, the dimensions that I have for of Dave's frustum are: 8" H, 10" LD and 6.25 " SD
So Dave's dimensions are smaller than NASA's by 1 inch both in Big D and in Length, but same small diameter, so rfmwguy does not have the same proportional ratio as the NASA frustum (rfmwguy's frustum is truncated sooner than NASA's):
Also please see my answer to your question previous page. thanks, FL
Not only that, but he also injects RF through middle of the big end. It will probably be easier to compare the real trace to a trace from FEKO.
What calculations is Dave referring to when he discusses his expected resonance natural frequency with his new dimensions?...soldering brought frequency down to abt 2.44 Ghz. Much closer to 2450 modeling target....
What model gives 2.45 GHz for Dave's new dimensions?
Is Dave's expected 2.45 GHz natural frequency based on a FEKO run for his new dimensions (shorter than NASA and smaller Big D than NASA) ?
inches
NASA rfmwguy (dimensions from FattyLumpkin)
LENGTH 9 8
BIG D 11 10
SMALL D 6.25 6.25 -
#2568 by Rodal on 18 May, 2016 16:02
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Dr. Rodal, the dimensions that I have for of Dave's frustum are: 8" H, 10" LD and 6.25 " SD
So Dave's dimensions are smaller than NASA's by 1 inch both in Big D and in Length, but same small diameter, so rfmwguy does not have the same proportional ratio as the NASA frustum (rfmwguy's frustum is truncated sooner than NASA's):
Also please see my answer to your question previous page. thanks, FL
Not only that, but he also injects RF through middle of the big end. It will probably be easier to compare the real trace to a trace from FEKO.
Did you run FEKO for rfmwguy's new dimensions?
Was Dave's intention in shortening his frustum and making the Big D smaller to get Dave's frustum to resonate in the very strange TM31x mode (so strange that NASA COMSOL's analyst was not able to assign a "p" value to it)?
Does FEKO confirm that Dave's new dimensions are small enough to resonate at 2.45 GHz in this very strange mode shape TM31x?
what is the approximate "p" value for this mode shape in FEKO for Dave's new dimensions?
or is FEKO showing Dave's new frustum dimension resonating at 2.45 GHz in another mode shape, perhaps TE213 ?
Is Dave trying to excite a TE mode shape or a TM mode shape?
If so, why make the frustum with dimensions to resonate in TM31x or TE213 instead of TM212 (NASA mode) or TE013 or TE012 (Shawyer and Yang's modes)?
Many questions
Would be interesting to know what is expected for Dave's experiment, before he actually runs it.
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#2569 by mwvp on 18 May, 2016 16:47
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Great discussion, yet...
...
In the particle viewpoint, the photon, traveling at the speed of light in vacuum c, has a momentum
where ν (Greek letter "nu") is the frequency and λ is the wavelength, where the frequency of the photon is the speed of light in vacuum c divided by the wavelength. Hence, as the wavelength of the photon decreases, its frequency must increase (and vice-versa).
...
My point is, we transmit or excite a fixed number of cycles-per-second into a waveguide. If the waveguide is filled with a higher permiability or permittivity material, the wavelength of the energy in the waveguide changes, the wave-vector (cycles/meter of waveguide) will change, but for any point in it, the cycles-per-second does not.
Similarly, in an optic fiber or hollow metallic guide, the path of the energy may be folded more or less according to its frequency, again resulting in a different wavelength and wave vector with respect to free space, but for any point, the cycles-per-unit time has not changed.
I guess this is the core of the Abraham-Minkowski issue; if we use a higher permiability/permittivity material or fold the path of the energy, we increase the energy-density and now Planks' constant demands we increase a photon momentum and frequency.
This can hardly be so (or so I would think). So we speak of energy being stored in the material, or the near-field.
To change the subject a bit, I now think I see how using a dielectric can result in static thrust, in contrast to my former fervent conviction that thrust in an EM Drive can only result dynamically due to Doppler shift in anisotropic dissipative tapered guide.
If a dielectric (such as polyethylene, Er~2), is used, I presume half the energy is in the vacuum field, and half polarizing the PE dipole moments. The wavelength and wave vectors in free space and PE will be different, a differing E and M potential will be present with consequent forces.
In other words, there are two fields or mode-patterns to consider; the one in free space and the one in the dielectric. Two different simulations should be run, and a difference calculated. Now although there will be one superposition of the two fields that would be experimentally measured, there will be consequent forces on the dielectric (and what's mechanically connected to it) to consider.
But when such a dielectric moves, it will drag (Fresnel drag) the stored EM energy in its inertial frame, reducing dynamic/Doppler forces that would otherwise result. -
#2570 by Rodal on 18 May, 2016 17:04
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Great discussion, yet...
I see how one can view it that way, prior to the data from Shawyer and NASA on dielectrics, but in view of the following experimental information:...
In the particle viewpoint, the photon, traveling at the speed of light in vacuum c, has a momentum
where ν (Greek letter "nu") is the frequency and λ is the wavelength, where the frequency of the photon is the speed of light in vacuum c divided by the wavelength. Hence, as the wavelength of the photon decreases, its frequency must increase (and vice-versa).
...
My point is, we transmit or excite a fixed number of cycles-per-second into a waveguide. If the waveguide is filled with a higher permiability or permittivity material, the wavelength of the energy in the waveguide changes, the wave-vector (cycles/meter of waveguide) will change, but for any point in it, the cycles-per-second does not.
Similarly, in an optic fiber or hollow metallic guide, the path of the energy may be folded more or less according to its frequency, again resulting in a different wavelength and wave vector with respect to free space, but for any point, the cycles-per-unit time has not changed.
I guess this is the core of the Abraham-Minkowski issue; if we use a higher permiability/permittivity material or fold the path of the energy, we increase the energy-density and now Planks' constant demands we increase a photon momentum and frequency.
This can hardly be so (or so I would think). So we speak of energy being stored in the material, or the near-field.
To change the subject a bit, I now think I see how using a dielectric can result in static thrust, in contrast to my former fervent conviction that thrust in an EM Drive can only result dynamically due to Doppler shift in anisotropic dissipative tapered guide.
If a dielectric (such as polyethylene, Er~2), is used, I presume half the energy is in the vacuum field, and half polarizing the PE dipole moments. The wavelength and wave vectors in free space and PE will be different, a differing E and M potential will be present with consequent forces.
In other words, there are two fields or mode-patterns to consider; the one in free space and the one in the dielectric. Two different simulations should be run, and a difference calculated. Now although there will be one superposition of the two fields that would be experimentally measured, there will be consequent forces on the dielectric (and what's mechanically connected to it) to consider.
But when such a dielectric moves, it will drag (Fresnel drag) the stored EM energy in its inertial frame, reducing dynamic/Doppler forces that would otherwise result.
1) Shawyer claims that he used dielectrics and the performance was inferior to the one without dielectrics. Upon reviewing the dielectrics he used (from his patents) one concludes that Shawyer used inorganic dielectrics with very high relative permittivity =38, precisely the ones that would result in greater difference between Abraham and Minkowski
2) When NASA used dielectrics similar to Shawyer (inorganic dielectrics with very high relative permittivity =38) NASA obtained similar results to Shawyer: inferior performance: insignificant values of anomalous force. Probably due to decrease in Q without an overriding benefit.
3) When NASA used anisotropic organic polymers as an insert, having a relative permittivity closer to 2, which is closer to the value of vacuum or air than to the inorganic dielectrics used by Shawyer, they obtained the highest values of anomalous force.
4) Hence the value of the polymer inserts used by NASA cannot be justified by the relative permittivity, as this runs contrary to the experimental data of both NASA and Shawyer.
5) The value of NASA's polymer insert can instead be justified on the basis of Prof. Woodward's hypothesis: it is the piezoresistive effect and the ELECTRO-STRICTIVE FORCE of the material that matters rather than the difference in permittivity. The experimental data from Shawyer and NASA indicate that this is not a dielectric effect. Hence the experimental data does not support the Abraham/Minkowski theory (polymer with rel.permittivity=2 gives much higher effect than inorganic dielectric with rel.permittivity=38), it rather rules against it, and instead may support Prof. Woodward's hypothesis. -
#2571 by Fugudaddy on 18 May, 2016 17:22
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Interesting new paper regarding non-integer Planck values for photons:
Title: "There are many ways to spin a photon: Half-quantization of a total optical angular momentum"
Link:
http://advances.sciencemag.org/content/2/4/e1501748.full
From the abstract:
The angular momentum of light plays an important role in many areas, from optical trapping to quantum information. In the usual three-dimensional setting, the angular momentum quantum numbers of the photon are integers, in units of the Planck constant ħ. We show that, in reduced dimensions, photons can have a half-integer total angular momentum. We identify a new form of total angular momentum, carried by beams of light, comprising an unequal mixture of spin and orbital contributions. We demonstrate the half-integer quantization of this total angular momentum using noise measurements. We conclude that for light, as is known for electrons, reduced dimensionality allows new forms of quantization.
seemed interesting, esp. in regards to their non-whole integer Planck constants...
Ronald
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#2572 by zen-in on 18 May, 2016 19:04
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Interesting new paper regarding non-integer Planck values for photons:
Title: "There are many ways to spin a photon: Half-quantization of a total optical angular momentum"
Link:
http://advances.sciencemag.org/content/2/4/e1501748.full
From the abstract:
The angular momentum of light plays an important role in many areas, from optical trapping to quantum information. In the usual three-dimensional setting, the angular momentum quantum numbers of the photon are integers, in units of the Planck constant ħ. We show that, in reduced dimensions, photons can have a half-integer total angular momentum. We identify a new form of total angular momentum, carried by beams of light, comprising an unequal mixture of spin and orbital contributions. We demonstrate the half-integer quantization of this total angular momentum using noise measurements. We conclude that for light, as is known for electrons, reduced dimensionality allows new forms of quantization.
seemed interesting, esp. in regards to their non-whole integer Planck constants...
Ronald
Planck's constant is a constant = 6.62607004 × 10-34 m2 kg / s. What the author refers to in his abstract is the half-integer quantization of the total angular momentum. This theory about photon orbital energies does not change Planck's constant. -
#2573 by FattyLumpkin on 18 May, 2016 19:30
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Dr Rodal, sorry for the inconvenience, here is the link: As aforementioned I'd start at 4105 FL
I've reiterated the questions I had below. -
#2574 by X_RaY on 18 May, 2016 19:32
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FYI
Q-study of TE01p in the truncated Brady-cone using higher "p"-values.
http://forum.nasaspaceflight.com/index.php?topic=39214.msg1536095#msg1536095
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#2575 by gustavo on 18 May, 2016 19:45
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My studies on the EmDrive based on Ray Tracing is done, paper is attached.
In paper it is described how the algorithm was made, and it is discussed some results obtained for some cases.
I'm running some simulations now with higher number of iterations (reflections), but it will take a longer time to get the results. Still with some issues with preallocating memory on the algorithm.
The studies were made considering a continuous beam of photons being reflected inside a truncated cone cavity.
The asymmetry of the cone geometry causes an imbalance in the angle of incidence between the two ends, which I believe is the main cause for the resulting net thust. Calculations with a geometry of a cylinder resulted in zero thrust.
Thrust is towards small end. -
#2576 by Monomorphic on 18 May, 2016 20:02
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The studies were made considering a continuous beam of photons being reflected inside a truncated cone cavity.
Great work! Two things: 1. Can you fun the simulation for a truncated cone with rounded endplates with the same center radius? 2. Suggest also running the simulation with the laser firing less randomly and more like the angle shown in this image.
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#2577 by FattyLumpkin on 18 May, 2016 20:08
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Dr. Rodal, I'll reiterate my questions re Sonny's talk so you don't have to go to previous pages to find them. Sonny says "able to get into" referring to power injected into the frustum. My question was: is there something preventing him from "getting" more power into the frustum? The reason for the question: for the NASA frustum the TE012 mode generated the best thrust for the amount of power that was injected. Why was not more power injected into the frustum... (an amount greater than 2.6 Watts)?
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#2578 by Rodal on 18 May, 2016 20:12
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Dr Rodal, sorry for the inconvenience, here is the link: As aforementioned I'd start at 4105 FL
Thank you so much for bringing this to our attention.
First observation is once again the EXCELLENT agreement between NASA's predicted Q factor and NASA's measured Q factor. There has been a lot of talk in the EM Drive pages questioning the validity of Q predictions, but such questioning runs against the experimental fact that NASA obtained excellent agreement between their predicted Q and measured Q, which goes to show the quality of their COMSOL Finite Element analysis.
Now to your question: yes it is indeed interesting that Dr. White says that NASA was able to input only 2.6 watts into mode shape TE012 while they were able to input many times as much into mode shape TM212.
It is not clear why this was so, but I agree that indeed it is noteworthy. Dr. White makes the point that although they were to get the highest force/inputPower for this mode shape TE012 than any other mode shape, they were unable to repeat the test because he says the proximity of other natural frequency resonances in the vicinity of this resonance made it too difficult to reproduce. I don't know the reason for their difficulty in reproducing this test result but it is noteworthy that this may be related to their inability to push more power into it. It is also noteworthy that this mode shape (TE012) is the same mode shape for which they did not get a significant anomalous force even when successfully inputting 10 times higher input power, at a higher frequency of resonance, without the polymer insert. It should also be pointed out that this mode shape is a transverse electric mode (TE012) that is notoriously more difficult to excite than the TM modes, and that this mode shape was the one used by Shawyer for his Demonstrator experiment.
My main guess is that NASA's difficulty in repeating this test and inputting more power into this mode shape (TE012) has to do with the way they tried to excite it, using a small loop near the inner surface of the cone,
which is not where the maximum Blongitudinal field intensity occurs, to try to excite the axial magnetic field that takes place in the longitudinal direction with a TE mode. Other experimenters have also run into difficulties in exciting TE mode shapes, not just experimentally, but also numerically, using Meep or using Feko. Prof. Collin discusses in one of his books the fact that it is more difficult to excite TE mode shapes, and so does the CERN School when discussing microwave cavities for particle accelerators.
If you encounter difficulties in exciting a mode shape, you are certainly going to run into difficulties into pushing a lot of power into it, when you happen to excite it. -
#2579 by Monomorphic on 18 May, 2016 20:19
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The studies were made considering a continuous beam of photons being reflected inside a truncated cone cavity.
Great work! Two things: 1. Can you fun the simulation for a truncated cone with rounded endplates with the same center radius? 2. Suggest also running the simulation with the laser firing less randomly and more like the angle shown in this image.
This is what that looks like for the first few dozen reflections.
