-
#1060 by ThereIWas3 on 31 Dec, 2015 21:54
-
The big stopper was it couldn't be modeled in meep but hasn't been put to sleep on my end.
I have found indication in the meep support mailing list that it can do circular polarization, though examples are hard to find. I have made inquiries. It does require using complex math and a custom 'source' definition. -
#1061 by X_RaY on 31 Dec, 2015 22:00
-
Happy new year!Good luck for all future experiments!
-
#1062 by ThereIWas3 on 31 Dec, 2015 22:25
-
Make it tuneble with the small plate coupled to the large via a Quartz rod through the center. The horn can now grow with thermal expansion and not loose resonance.
Would not the metal frustrum expand circumferentially as well as linearly? In a model where that may be significant it seems the only way to actually build one of these is to use a controlled digital osciallator and TWT amplifier, so that the frequency can be shifted lower in a controlled fashion as the cavity expands. If I was going to actually build one I might use X-band (10 GHz) because parts for that are easy to scrounge, and are much used by Hams. -
#1063 by SeeShells on 31 Dec, 2015 22:29
-
Then the issue becomes getting a circular polarizing antenna into the EMDrive cavity.The big stopper was it couldn't be modeled in meep but hasn't been put to sleep on my end.
I have found indication in the meep support mailing list that it can do circular polarization, though examples are hard to find. I have made inquiries. It does require using complex math and a custom 'source' definition.
I was thinking 2- 1/2 wave dipoles, 1/4 wave offset should give a circular polarizing pattern. and fit into the cavity or a modified backfire dipole.
Shell -
#1064 by rq3 on 31 Dec, 2015 23:09
-
Make it tuneble with the small plate coupled to the large via a Quartz rod through the center. The horn can now grow with thermal expansion and not loose resonance.
Would not the metal frustrum expand circumferentially as well as linearly? In a model where that may be significant it seems the only way to actually build one of these is to use a controlled digital osciallator and TWT amplifier, so that the frequency can be shifted lower in a controlled fashion as the cavity expands. If I was going to actually build one I might use X-band (10 GHz) because parts for that are easy to scrounge, and are much used by Hams.
Yes, this has been discussed, and ignored, ad nauseum. There has been slow acceptance of my idea that trying to tune a cavity to a magnetron is pointless, while frequency or phase locking the SOURCE to the changing frustum dimensions gives much more control of the experiment, which already has far too many variables.
A twit (TWT, or Traveling Wave Tube) amplifier would be hard pressed to provide the power output apparently required for the Emdrive to provide any meaningful "thrust". As I've said before, a klystron, or modern solid state amplifier, when driven by a good lab quality synthesizer would provide a microwave source capable of independant modulation in phase, frequency, and amplitude. Or all simultaneously (I/Q modulation).
Without this capability, it's all barking in the dark. Again, with a magnetron, if it appears to demonstrate thrust, you won't know why. If it doesn't, you won't know why.
There are very good reasons why magnetrons are used for nothing but heating and ripping atoms out of substrates (magnetron sputtering). They certainly aren't used in anything that requires tight, precise frequency control (like RADAR or resonant cavities).
And on the subject of resonant cavities; there seems to be a misconception that Q is an amplification effect. There have been posts that imply a 1 watt input to a cavity with a Q of 10,000 yields a cavity POWER of 10,000 watts. This is totally bogus. The Q value of a tuned cavity, of whatever shape or dimension, can only describe the circuit's ability to select for a particular frequency. The higher the Q, the tighter the bandwidth, and the energy NOT included in the selected bandwidth is either reflected to the source, or dissipated as heat.
Personally, I'm at a loss why no one here has approached firms like Agilent. When I worked for HP/Agilent as a microwave engineer, if someone had wandered into our field office, described what they were doing, and asked for help, I would have picked up the phone and called the dispatch center. Within a week I would have a "loaner" synthesizer, all the wavequide required, detectors, and maybe an 8510 vector network analyzer. I may catch hell for suggesting this (from my ex-employer), but has anyone tried? All they can do is say no. What have you to lose? I'm sure things have changed in the intervening years, but it's certainly worth a shot. No? Be assured that there were a few "off the street engineers" that got a firm "NO" from me, but there were more that got that phone call to the dispatch center.
I'm also amazed that no-one has suspended a 100 watt lightbulb from their balance beam, turned it on, and seen what kind of response they get. Or better yet, stuff the light bulb in their frustum and see what response they get. Try it. You might be surprised. After all, a dissipated watt is a dissipated watt, whether it's ultimate source is "long-wave" (microwave magnetron and copper), or shortwave (AC/DC infrared and tungsten).
Disclaimer: I've been following the "EmDrive" for many years. I personally think it will turn out to be polywater, but would dearly love to be convinced otherwise. -
#1065 by VAXHeadroom on 31 Dec, 2015 23:27
-
...
The issues appear to be with the Meep model. The electromagnetic field distribution in the Meep model has not been verified vs. exact solutions, experiments and independent COMSOL models insofar as the electromagnetic fields are concerned. To start with, 1% of a microsecond is thousands of times less than the tens of microseconds required to establish the standing waves for resonance. There are also many issues surrounding pre and post-processing of the data and convergence of the Meep model.
Things can get quite complicated when you must consider that the frustum isn't simply a cone with the resonance between the endplates alone but between the dual waveguide injectors. You have to look at it as almost two separate resonating cavities one playing off on the other. Microwave modes in a cavity can reflect of walls but also reflect off other modes to create a TE01 or about anything else you desire. It isn't a surprise when other modes can be present.
The exponential growth of the electromagnetic fields has not been addressed either.
Kudos to VaxHeadRoom for looking at this.
Thank you - that means a lot to me!QuoteOne cannot take for granted the output of a numerical model: it needs to be verified.
The huge error of 113 times on the material input leading to an unreasonable Q (and hence to unreasonable damping of electromagnetic modes) was only addressed during the past few days...
I *think* this was addressed in the model file I have, but aero will need to verify that...
Assuming this looks to be a reasonable result, I now have a toolpath with which I can create this output from a meep model in 24-48 hours (for the given simulation time and resolution we are currently using). Additionally, I was running the model with the highest spatial resolution I could fit into memory. A lower resolution may be reasonable for showing this mode shape which would mean either we can run it faster (produce the output in a shorter wall-clock time) or we can run it for a longer simulation time. With a lower resolution I can probably get this up to 10x the simulation time we are currently producing which would run about 48 hours for meep and another 1-2 to gen the graphic. I'm certainly willing to give that a go...HAPPY NEW YEAR TO ALL!! -
#1066 by oyzw on 31 Dec, 2015 23:39
-
An EM Drive on a "boat" floating in a liquid fluidQuoteWrought iron Posted at 2014-2-20 08:42
This is a good thing, ah, there is no experimental video ah, Yang did you move in?
No boat experiment can not be convincing.
Need TellMeAgain or someone else fluent in Chinese to provide better translation from the Chinese forums to interpret this information
Wrought iron's post:QuoteQuotepershine (another user) posted in 2014-2-19 23:35
You could not convince us if you do not do a boat experiment.
This is a good thing. Do you have a video of the experiment? Did yang recruit you?
And if you are curious, I am the Wrought iron who have debated with him for years.
Thank you. What does "boat experiment" mean specifically? Does it refer to:
1) an EM Drive on a rotary platform suspended on an air bearing as in SPR Shawyer experiment video of the EM Drive Demonstrator
2) An EM Drive on a "boat" floating in a liquid fluid
3) something else -
#1067 by OnlyMe on 31 Dec, 2015 23:41
-
Make it tuneble with the small plate coupled to the large via a Quartz rod through the center. The horn can now grow with thermal expansion and not loose resonance.
Would not the metal frustrum expand circumferentially as well as linearly? In a model where that may be significant it seems the only way to actually build one of these is to use a controlled digital osciallator and TWT amplifier, so that the frequency can be shifted lower in a controlled fashion as the cavity expands. If I was going to actually build one I might use X-band (10 GHz) because parts for that are easy to scrounge, and are much used by Hams.
Yes, this has been discussed, and ignored, ad nauseum. There has been slow acceptance of my idea that trying to tune a cavity to a magnetron is pointless, while frequency or phase locking the SOURCE to the changing frustum dimensions gives much more control of the experiment, which already has far too many variables.
A twit (TWT, or Traveling Wave Tube) amplifier would be hard pressed to provide the power output apparently required for the Emdrive to provide any meaningful "thrust". As I've said before, a klystron, or modern solid state amplifier, when driven by a good lab quality synthesizer would provide a microwave source capable of independant modulation in phase, frequency, and amplitude. Or all simultaneously (I/Q modulation).
Without this capability, it's all barking in the dark. Again, with a magnetron, if it appears to demonstrate thrust, you won't know why. If it doesn't, you won't know why.
Personally, I'm at a loss why no one here has approached firms like Agilent. When I worked for HP/Agilent as a microwave engineer, if someone had wandered into our field office, described what they were doing, and asked for help, I would have picked up the phone and called the dispatch center. Within a week I would have a "loaner" synthesizer, all the wavequide required, detectors, and maybe an 8510 vector network analyzer. I may catch hell for suggesting this (from my ex-employer), but has anyone tried? All they can do is say no. What have you to lose? I'm sure things have changed in the intervening years, but it's certainly worth a shot. No? Be assured that there were a few "off the street engineers" that got a firm "NO" from me, but there were more that got that phone call to the dispatch center.
I'm also amazed that no-one has suspended a 100 watt lightbulb from their balance beam, turned it on, and seen what kind of response they get. Or better yet, stuff the light bulb in their frustum and see what response they get. Try it. You might be surprised. After all, a dissipated watt is a dissipated watt, whether it's ultimate source is "long-wave" (microwave magnetron and copper), or shortwave (AC/DC infrared and tungsten).
The light bulb caused me to think back, as dangerous as that may be in my case.., in Yang's data she (I assume) calculated that out of 200 watts of raw magnetron power there was only a practical output of 13 watts.
If that is true the only way to accurately simulate the thermal effects, would be first to run the frustum with the magnetron recording the actual temperature of the frustum.., and then use a dimmiable light bulb to bring up the dummy load to match....
Even then there will be problems with a mismatch in the way the microwaves heat the frustum and the way a light bulb would. The light bulb will heat all surfaces reasonably equally.., remember that Shell said the walls felt cool, while the endplates felt warm. No numbers but it suggests that the microwaves do not heat the walls and end plates in a uniform manner, as would be expected from a heat source like a light bulb. -
#1068 by rq3 on 31 Dec, 2015 23:55
-
Make it tuneble with the small plate coupled to the large via a Quartz rod through the center. The horn can now grow with thermal expansion and not loose resonance.
Would not the metal frustrum expand circumferentially as well as linearly? In a model where that may be significant it seems the only way to actually build one of these is to use a controlled digital osciallator and TWT amplifier, so that the frequency can be shifted lower in a controlled fashion as the cavity expands. If I was going to actually build one I might use X-band (10 GHz) because parts for that are easy to scrounge, and are much used by Hams.
Yes, this has been discussed, and ignored, ad nauseum. There has been slow acceptance of my idea that trying to tune a cavity to a magnetron is pointless, while frequency or phase locking the SOURCE to the changing frustum dimensions gives much more control of the experiment, which already has far too many variables.
A twit (TWT, or Traveling Wave Tube) amplifier would be hard pressed to provide the power output apparently required for the Emdrive to provide any meaningful "thrust". As I've said before, a klystron, or modern solid state amplifier, when driven by a good lab quality synthesizer would provide a microwave source capable of independant modulation in phase, frequency, and amplitude. Or all simultaneously (I/Q modulation).
Without this capability, it's all barking in the dark. Again, with a magnetron, if it appears to demonstrate thrust, you won't know why. If it doesn't, you won't know why.
Personally, I'm at a loss why no one here has approached firms like Agilent. When I worked for HP/Agilent as a microwave engineer, if someone had wandered into our field office, described what they were doing, and asked for help, I would have picked up the phone and called the dispatch center. Within a week I would have a "loaner" synthesizer, all the wavequide required, detectors, and maybe an 8510 vector network analyzer. I may catch hell for suggesting this (from my ex-employer), but has anyone tried? All they can do is say no. What have you to lose? I'm sure things have changed in the intervening years, but it's certainly worth a shot. No? Be assured that there were a few "off the street engineers" that got a firm "NO" from me, but there were more that got that phone call to the dispatch center.
I'm also amazed that no-one has suspended a 100 watt lightbulb from their balance beam, turned it on, and seen what kind of response they get. Or better yet, stuff the light bulb in their frustum and see what response they get. Try it. You might be surprised. After all, a dissipated watt is a dissipated watt, whether it's ultimate source is "long-wave" (microwave magnetron and copper), or shortwave (AC/DC infrared and tungsten).
The light bulb caused me to think back, as dangerous as that may be in my case.., in Yang's data she (I assume) calculated that out of 200 watts of raw magnetron power there was only a practical output of 13 watts.
If that is true the only way to accurately simulate the thermal effects, would be first to run the frustum with the magnetron recording the actual temperature of the frustum.., and then use a dimmiable light bulb to bring up the dummy load to match....
Even then there will be problems with a mismatch in the way the microwaves heat the frustum and the way a light bulb would. The light bulb will heat all surfaces reasonably equally.., remember that Shell said the walls felt cool, while the endplates felt warm. No numbers but it suggests that the microwaves do not heat the walls and end plates in a uniform manner, as would be expected from a heat source like a light bulb.
And that is exactly why experimenters need to be able to determine how much energy is being dissipated in the frustum. It DOES NOT MATTER what surface it is being dissipated from, IT ONLY MATTERS how much energy is being dissipated. Vector network analysis of the microwave injection will tell accurately what is being injected and reflected. The delta is heat. Heat (from whatever source), and magnetic forces from lead wires are the two MAJOR variables in this experiment.
Again, as a "sub-experiment", suspend a 100 watt bulb from the experimental balance beam. Turn it on. Measure the beam displacement. Turn it off. Measure the beam displacement. What do you see? If you add microwaves in a sealed can, is there a difference? Do it again with the same 100 watt bulb in the sealed can, but no microwaves. Is there a difference?
Then do the whole sequence again, with and without microwaves, with the can inverted from its previous position. Do each of these 100 times, with exact timing for application of applied energy, presence of expected energy, and recorded displacement for each.
Then do it all again under hard vacuum. Less than 10-6 torr. That's 0.000001 torr. Decent industial vacuum. Anything grosser than that will invoke molecular rebound effects (see Crook's radiometer). -
#1069 by ThereIWas3 on 01 Jan, 2016 00:02
-
There are several ways to create a circulaly polarized wave. crossed dipoles is one. A thin dielectric placed at a 45 degree angle within a cylindrical waveguide already fed with linearly polarization can do it too, as well as an end fed helical spring.
I know my Meep code is using the corrected permittivity numbers and I think aero has made the same fix. -
#1070 by SteveD on 01 Jan, 2016 00:27
-
Don't know, maybe a Lot of excess heat. Isn't it better to clean up the magnetron output before insertion?
that's not A magnetron on the end but a waveguide. The magnetron is a 1/4 wavelength snub antenna with a cap launcher on the end.I think this would be an interesting shape to investigate. It is an exponential horn with a flat plate at the small end (where the sides are nearly parallel) and spherical at the other, with radius chosen so that there is a right angle where it meets the flaring horn.
RF to be introduced at the center of the small end in the center of the small plate. The plate could be moved in and out to adjust for resonance.
Fabrication might be difficult, unless you had access to a manufacturer of brass instruments.
Rf insertion in the small end might produce a null as oer Rfmwguy's first run.
He might have been better off using the waveguide attached to the magnetron to the top like in the picture with a Z-match hole in the top plate. IMHO.
How badly would using a resonance absorption isolator for the waveguide break things?
Shell
Wondering if it would be able to protect the antenna if the cavity tried to dump into it. -
#1071 by R.W. Keyes on 01 Jan, 2016 00:52
-
Arc-Fault Interrupters will ruin all the fun!
Why I'll not be playing around with my magnetron on New Years Eve.
Happy New Year Everyone!!!!
Shell -
#1072 by SeeShells on 01 Jan, 2016 00:53
-
Why couple the copper of the frustum together where all the thermal expansions can link together causing a almost a chaotic thermal deformation where you will be hard pressed to make sure your incoming RF will even excite anything even if you lock it? Stabilize the frustum first, allow it to thermally grow in a controlled way first, then phase lock it if you need it.Make it tuneble with the small plate coupled to the large via a Quartz rod through the center. The horn can now grow with thermal expansion and not loose resonance.
Would not the metal frustrum expand circumferentially as well as linearly? In a model where that may be significant it seems the only way to actually build one of these is to use a controlled digital osciallator and TWT amplifier, so that the frequency can be shifted lower in a controlled fashion as the cavity expands. If I was going to actually build one I might use X-band (10 GHz) because parts for that are easy to scrounge, and are much used by Hams.
Shell -
#1073 by SeeShells on 01 Jan, 2016 01:02
-
HAPPY NEW YEAR
-
#1074 by rfmwguy on 01 Jan, 2016 01:41
-
From one of my old posts in T3
Then the issue becomes getting a circular polarizing antenna into the EMDrive cavity.The big stopper was it couldn't be modeled in meep but hasn't been put to sleep on my end.
I have found indication in the meep support mailing list that it can do circular polarization, though examples are hard to find. I have made inquiries. It does require using complex math and a custom 'source' definition.
I was thinking 2- 1/2 wave dipoles, 1/4 wave offset should give a circular polarizing pattern. and fit into the cavity or a modified backfire dipole.
Shell
http://www.readymaderc.com/store/index.php?main_page=product_info&cPath=11_45_48&products_id=1538
-
#1075 by SeeShells on 01 Jan, 2016 02:38
-
Have this one made with a 3D printer that would allow you to wrap the guides a 10 Gauge solid copper wire.
From one of my old posts in T3
Then the issue becomes getting a circular polarizing antenna into the EMDrive cavity.The big stopper was it couldn't be modeled in meep but hasn't been put to sleep on my end.
I have found indication in the meep support mailing list that it can do circular polarization, though examples are hard to find. I have made inquiries. It does require using complex math and a custom 'source' definition.
I was thinking 2- 1/2 wave dipoles, 1/4 wave offset should give a circular polarizing pattern. and fit into the cavity or a modified backfire dipole.
Shell
http://www.readymaderc.com/store/index.php?main_page=product_info&cPath=11_45_48&products_id=1538
This is small enough to insert into the large end.
Shell
-
#1076 by SteveD on 01 Jan, 2016 03:31
-
An EM Drive on a "boat" floating in a liquid fluid
How about pushing a balloon? Less issues with fluids, intuitively clearer what the implications might be. -
#1077 by TheTraveller on 01 Jan, 2016 05:05
-
Have learned Oyzw has a TE013 molded frustum for sale.
Yes ！ D - big: D - 290 mm small: 170 mm L - center: 240 mm TE013（pure copper sheet （ thickness 1.25 mm ））. If you need TE012, I can modify the mould.
Asking for more detailed engineering data.
Hi Oyzw,
Attached is the data analysis for your TE013 frustum.
TE013 resonance (assuming you can excite TE013) is around 2.53 GHz with a unloaded Q of around 60k. Private data from Oyzw suggest the TE013 resonance range is 2.54 to 2.55 Ghz. So we agree.
Could improve the predicted Force generation of approx 0.126N/kW by reducing the small end diameter (generates a higher Shawyer Design Factor) but you would also need to modify the length to obtain the same TE013 resonance.
Would also suggest the resonance is a bit high at 2.53 GHz, which could stop it being driven by a freq splatter cleaned up maggie as Shell and myself are working on. Well really just Shell now as my tight focus is now on the spherical end plate 100W Rf amp with VSWR best freq tracking build.
Phil
-
#1078 by VAXHeadroom on 01 Jan, 2016 06:06
-
Have this one made with a 3D printer that would allow you to wrap the guides a 10 Gauge solid copper wire.
From one of my old posts in T3
Then the issue becomes getting a circular polarizing antenna into the EMDrive cavity.The big stopper was it couldn't be modeled in meep but hasn't been put to sleep on my end.
I have found indication in the meep support mailing list that it can do circular polarization, though examples are hard to find. I have made inquiries. It does require using complex math and a custom 'source' definition.
I was thinking 2- 1/2 wave dipoles, 1/4 wave offset should give a circular polarizing pattern. and fit into the cavity or a modified backfire dipole.
Shell
http://www.readymaderc.com/store/index.php?main_page=product_info&cPath=11_45_48&products_id=1538
This is small enough to insert into the large end.
Shell
I have a 3D printer. Just let me know if something is needed!
-
#1079 by xexorian on 01 Jan, 2016 06:10
-
Happy new years everyone!
I have been following the EMDrive discussion since before it was even here on the NSF forums. I'm just curious why no one has taken into account that mass=energy, and continues to try to come up with a general theory of how it would work, and then to evolve that theory into real physics equations.
With my limited knowledge even I can acknowledge that something like the conversion of energy seems plausible. Rockets work by expelling gas, (consuming gas), why would a hypothetical as-of-yet-unknown device not be able to convert electrical energy (which has an equivalent of mass) into kinetic energy or thrust?
Also; barring all the allegations that it breaks the COE. I find this very doubtful. As has been stated by many, one the thing has yet to lift off the ground, or move itself (as in the apparatus that could be defined as the engine). Two, there is apparently a lot of heat loss, and as with any other classical phenomenon such as friction, the generation and loss of heat seems to fit the conversion of energy. In other words, it would seem as if 'work' is being done.
And, finally, all of the people who say at an expected velocity the thrust excedes the input, that seems ridiculous, obviously adding any sort of weight or 'friction' would suspend any further increase in velocity.
IE: If your spaceplane is flying at a million miles a second and crashes into an object not moving at a million miles a second, there will be a transfer of energy to mass, and your spaceplane, assuming it could survive such a thing, would SLOW DOWN. You would not be able to generate more energy from this, it seems really ridiculous there are people calling it a perpetual motion device.
power in =/= power out, clearly, by any of the conducted tests. This seems to fit the conservation of energy and the laws of thermodynamics, the only thing fringe about it at this point is if it's producing thrust or if the ways we have been measuring it are measuring the expansion of metal due to thermal effects.
I think the light bulb test rq3 posited would be an excellent candidate to test this critique and super cheap. Anyone can still go pickup 3 or 4 100w light bulbs from a Home Depot (in the USA) and wire up a light rack that can be held or even mounted very cheaply to test the effects of thermal expansion of the metal involved in the experiment from different angles, on different parts, and see if any of it correlates to a heat map.
Not only that, thermal cameras are considerably cheaper than they were when Jurassic Park came out in theaters back in 1993. Surely one could be used to view the heat of the metal from a hypothetical device and visually map out where the metal is being heated by the electromagnetic waves inside of their setup.
ps.
"If you always put limit on everything you do, physical or anything else. It will spread into your work and into your life. There are no limits. There are only plateaus, and you must not stay there, you must go beyond them."
-Bruce Lee
