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#2400
by
flux_capacitor
on 09 Feb, 2017 10:30
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Can anyone confirm this one (Mono?)
Big_D=26cm
Height=30cm
Small_D=14cm
Resonant frequency: 2.4489Ghz
Excellent!
Using your dimensions my spreadsheet gives TE013=2.43769GHz
Feko TE013=2.449477GHz
At 14cm small diameter, cylindrical cut-off frequency (lower limit) is 2.6108GHz for TE013. The frequency you want to use is below that value so your diameter is below cut-off diameter. For that reason TheTraveller's spreadsheet can't find any Df or resonance for these dimensions at 2.4489Ghz.
I don't say your frustum won't resonate, it will. Just that Shawyer claims the produced force will be very small when using a small end diameter below the equivalent cylindrical cut-off diameter (or also too much above, by the way). the difficult trick would be to make the small end diameter as small as possible wrt to the resonant frequency, but always keeping it above the cut-off diameter.
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#2401
by
X_RaY
on 09 Feb, 2017 11:43
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Can anyone confirm this one (Mono?)
Big_D=26cm
Height=30cm
Small_D=14cm
Resonant frequency: 2.4489Ghz
Excellent!
Using your dimensions my spreadsheet gives TE013=2.43769GHz
Feko TE013=2.449477GHz
At 14cm small diameter, cylindrical cut-off frequency (lower limit) is 2.6108GHz for TE013. The frequency you want to use is below that value so your diameter is below cut-off diameter. For that reason TheTraveller's spreadsheet can't find any Df or resonance for these dimensions at 2.4489Ghz.
I don't say your frustum won't resonate, it will. Just that Shawyer claims the produced force will be very small when using a small end diameter below the equivalent cylindrical cut-off diameter (or also too much above, by the way). the difficult trick would be to make the small end diameter as small as possible wrt to the resonant frequency, but always keeping it above the cut-off diameter.
Since there is no independent experimental proof of this, I think its better someone goes beyond this "rule" and try it. A lot of other statements TT came up with in the past were nonsensical like:
#no radiation preasure at the sidewall
#no resonance beyond the cutoff diameter as calculated for a cylindrical WG
#...
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#2402
by
Kenjee
on 09 Feb, 2017 11:51
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Can anyone confirm this one (Mono?)
Big_D=26cm
Height=30cm
Small_D=14cm
Resonant frequency: 2.4489Ghz
Excellent!
Using your dimensions my spreadsheet gives TE013=2.43769GHz
Feko TE013=2.449477GHz
Cool, thnx, now look at the 2.4817Ghz on the same dimensions, I find this
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#2403
by
Monomorphic
on 09 Feb, 2017 12:52
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Can anyone confirm this one (Mono?)
Big_D=26cm
Height=30cm
Small_D=14cm
Resonant frequency: 2.4489Ghz
Sorry, I was asleep, but I am glad X_Ray could help you. With a small loop antenna, I get TE013 at 2.4506Ghz.
It was mentioned that this cavity has a small end with a diameter that is too small for cutoff. While I agree that we should try a cavity that stretches this rule, this cavity is an extreme example with the big end having higher surface currents than the small end. So not only are the surface currents highest on the sidewalls, the big end also has higher currents than the small end.
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#2404
by
Monomorphic
on 09 Feb, 2017 14:31
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It's been a long time since I recorded a walk-around of my test rig. Now that a bulk of the construction is complete, I only expect incremental changes such as higher power amps, an ADC, bi-directional coupler, and perhaps an additional battery. I forgot to mention the usb hub and spectrum analyser, in addition to the signal generator, are all powered by the secondary battery. The kangaroo PC has its own internal battery good for four hours.
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#2405
by
Kenjee
on 09 Feb, 2017 16:05
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As you may notice, most of the time I dont know what I`m doing but I have time to experiment with geometry.
So if you don`t mind I will post some of simulation that I find interesting.
This one is Mono`s dimensions with opposite spherical caps.
p.s. If its not relevant I`ll stop.
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#2406
by
TheTraveller
on 09 Feb, 2017 16:12
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Can anyone confirm this one (Mono?)
Big_D=26cm
Height=30cm
Small_D=14cm
Resonant frequency: 2.4489Ghz
Excellent!
Using your dimensions my spreadsheet gives TE013=2.43769GHz
Feko TE013=2.449477GHz
At 14cm small diameter, cylindrical cut-off frequency (lower limit) is 2.6108GHz for TE013. The frequency you want to use is below that value so your diameter is below cut-off diameter. For that reason TheTraveller's spreadsheet can't find any Df or resonance for these dimensions at 2.4489Ghz.
I don't say your frustum won't resonate, it will. Just that Shawyer claims the produced force will be very small when using a small end diameter below the equivalent cylindrical cut-off diameter (or also too much above, by the way). the difficult trick would be to make the small end diameter as small as possible wrt to the resonant frequency, but always keeping it above the cut-off diameter.
Since there is no independent experimental proof of this, I think its better someone goes beyond this "rule" and try it. A lot of other statements TT came up with in the past were nonsensical like:
#no radiation preasure at the sidewall
#no resonance beyond the cutoff diameter as calculated for a cylindrical WG
#...
And yet the eddy current max density in the small end plate is much less than the max eddy current density in the ring on the side wall at the small end.
Very clearly showing the small end plate is operating beyond cutoff and very little energy is reaching the small end plate. I call that operating beyond cutoff.
Do you have another explanation as to why as the small end diameter reduces, at some point the end plate eddy currents start DECREASING as the small end side wall eddy current starts INCREASING?
Would you agree the decreasing small end plate eddy current density is indicating that less and less, as the diameter decreases, energy is reaching the small end plate? If not do you have some other explination why at some point in reducing small end plate diameter, it's eddy currents start to decrease?
FEKO can't model radiation pressure so why bring that issue up when discussion what FEKO can tell us about thruster design? I have yet to measure the radiation pressure on the side walls, so please don't make statements about my opinion. What you quoted was what Roger advises and I have passed on.
BTW the spreadsheet is not modeling the thruster as a cylinder. Guide wavelength is calculated at 65k points along the axis as the diameter alters. No need to do that with a cylinder.
When will you publish your spreadsheet for others to use and critique as I have done for many years?
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#2407
by
Donosauro
on 09 Feb, 2017 17:38
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Thanks, Monomorphic! It was nice to get such a complete view into your setup and general approach. Your transparency is commendable.
I look forward to seeing how this goes.
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#2408
by
WarpTech
on 09 Feb, 2017 17:53
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Can anyone confirm this one (Mono?)
Big_D=26cm
Height=30cm
Small_D=14cm
Resonant frequency: 2.4489Ghz
Excellent!
Using your dimensions my spreadsheet gives TE013=2.43769GHz
Feko TE013=2.449477GHz
...but how close are the other modes? This frustum is long and narrow, with a small angle. My understanding is there will be other modes very close to the TE013 frequency, that will interfere.
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#2409
by
TheTraveller
on 09 Feb, 2017 18:18
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Can anyone confirm this one (Mono?)
Big_D=26cm
Height=30cm
Small_D=14cm
Resonant frequency: 2.4489Ghz
Excellent!
Using your dimensions my spreadsheet gives TE013=2.43769GHz
Feko TE013=2.449477GHz
...but how close are the other modes? This frustum is long and narrow, with a small angle. My understanding is there will be other modes very close to the TE013 frequency, that will interfere.
WT,
The small end is very clearly in cutoff (very little small end plate eddy currents / very little energy reaching the small end plate vs the eddy currents in the sidewall ring at the small end), so why bother?
It amazes me that the guys here accept Roger's advise to use TE013 but ignore / reject his 0.82 small end cutoff rule even though the FEKO sims clearly show Small End cutoff occurring when looking at the small end plate eddy currents vs the side wall small end eddy currents?
Go figure as his dual advise (TE013 and 0.82 cutoff) are to be used together.
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#2410
by
X_RaY
on 09 Feb, 2017 18:30
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Can anyone confirm this one (Mono?)
Big_D=26cm
Height=30cm
Small_D=14cm
Resonant frequency: 2.4489Ghz
Excellent!
Using your dimensions my spreadsheet gives TE013=2.43769GHz
Feko TE013=2.449477GHz
At 14cm small diameter, cylindrical cut-off frequency (lower limit) is 2.6108GHz for TE013. The frequency you want to use is below that value so your diameter is below cut-off diameter. For that reason TheTraveller's spreadsheet can't find any Df or resonance for these dimensions at 2.4489Ghz.
I don't say your frustum won't resonate, it will. Just that Shawyer claims the produced force will be very small when using a small end diameter below the equivalent cylindrical cut-off diameter (or also too much above, by the way). the difficult trick would be to make the small end diameter as small as possible wrt to the resonant frequency, but always keeping it above the cut-off diameter.
Since there is no independent experimental proof of this, I think its better someone goes beyond this "rule" and try it. A lot of other statements TT came up with in the past were nonsensical like:
#no radiation preasure at the sidewall
#no resonance beyond the cutoff diameter as calculated for a cylindrical WG
#...
And yet the eddy current max density in the small end plate is much less than the max eddy current density in the ring on the side wall at the small end.
Very clearly showing the small end plate is operating beyond cutoff and very little energy is reaching the small end plate. I call that operating beyond cutoff.
Do you have another explanation as to why as the small end diameter reduces, at some point the end plate eddy currents start DECREASING as the small end side wall eddy current starts INCREASING?
Would you agree the decreasing small end plate eddy current density is indicating that less and less, as the diameter decreases, energy is reaching the small end plate? If not do you have some other explination why at some point in reducing small end plate diameter, it's eddy currents start to decrease?
FEKO can't model radiation pressure so why bring that issue up when discussion what FEKO can tell us about thruster design? I have yet to measure the radiation pressure on the side walls, so please don't make statements about my opinion. What you quoted was what Roger advises and I have passed on.
BTW the spreadsheet is not modeling the thruster as a cylinder. Guide wavelength is calculated at 65k points along the axis as the diameter alters. No need to do that with a cylinder.
When will you publish your spreadsheet for others to use and critique as I have done for many years?
Can anyone confirm this one (Mono?)
Big_D=26cm
Height=30cm
Small_D=14cm
Resonant frequency: 2.4489Ghz
Excellent!
Using your dimensions my spreadsheet gives TE013=2.43769GHz
Feko TE013=2.449477GHz
...but how close are the other modes? This frustum is long and narrow, with a small angle. My understanding is there will be other modes very close to the TE013 frequency, that will interfere.
WT,
The small end is very clearly in cutoff (very little small end plate eddy currents / very little energy reaching the small end plate vs the eddy currents in the sidewall ring at the small end), so why bother?
It amazes me that the guys here accept Roger's advise to use TE013 but ignore / reject his 0.82 small end cutoff rule even though the FEKO sims clearly show Small End cutoff occurring when looking at the small end plate eddy currents vs the side wall small end eddy currents?
Go figure as his dual advise (TE013 and 0.82 cutoff) are to be used together.
It seems you got a problem with the fact that the wave will more and more reflected at the sidewall instead of the endplate when the small diameter is below the cutoff diameter because your spreadsheet can't calculate this situation?? What else is the problem where exactly the reflection take place?
There is more than one way to overcome this problem using the well known equations.
I explaned the basic ideas I use in the past several times. Sorry but as far as I see you could do the work by yourself even it takes a while.
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#2411
by
Monomorphic
on 09 Feb, 2017 18:31
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This one is Mono`s dimensions with opposite spherical caps.
I don't think you are using the dimensions for the current as-built TE013 emdrive I am testing. It looks too long and narrow. My current dims are:
Big_D: 29.9cm
Height: 24cm
Small_D: 17.8cm
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#2412
by
TheTraveller
on 09 Feb, 2017 18:37
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This one is Mono`s dimensions with opposite spherical caps.
I don't think you are using the dimensions for the current as-built TE013 emdrive I am testing. It looks too long and narrow. My current dims are:
Big_D: 29.9cm
Height: 24cm
Small_D: 17.8cm
Glad to see your small end plate is clearly NOT in cutoff as it's eddy current are significantly greater than the upper small end side wall eddy currents. This is as it should be as per Roger's TE013 and 0.82 cutoff advise.
Nicely done!
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#2413
by
TheTraveller
on 09 Feb, 2017 18:40
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It seems you got a problem with the fact that the wave will more and more reflected at the sidewall instead of the endplate when the small diameter is below the cutoff diameter because your spreadsheet can't calculate this situation?? What else is the problem where exactly the reflection take place?
There is more than one way to overcome this problem using the well known equations.
I explaned the basic ideas I use in the past several times.
No problem at all.
The FEKO reduced small end plate eddy currents vs the small end side wall eddy currents SHOUT OUT there is LESS Rf energy reaching the small end plate. If you can't see the small end plate is in cutoff, ie less Rf energy reaching it, well there is little to discuss.
FEKO is clearly showing any who will listen that Roger's 0.82 cutoff small end rule works. Yet you ignore the reducing small end plate diameter reducing (below cutoff) eddy current data that FEKO produces. Why?
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#2414
by
Rodal
on 09 Feb, 2017 18:57
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One interpretation of this is that Shaywer (who, although being the inventor of the EM Drive, has failed to report a single experiment performed in a vacuum chamber, although he has been at this for decades now) has measured an experimental artifact due to thermal convection heating of the end plate.
Following Shawyer's cut-off rule and TE013:
ends up with much greater heating (surface losses W/m^2) of the small end plate than the big end plate. Such heating will result in a reduction of the density of the adjacent air, and hence into natural thermal convection, as a region of smaller density of air will be produced adjacent to the small end, and this will "suck" the EM Drive towards the small end.
Naturally, if the EM Drive is made with dimensions such that the small end is in cut-off conditions, the small end will be less and less heated, and this will result in smaller and smaller such forces due to thermal convection.
It is likely that builders conducting this experiment under ambient pressure will also measure these thermal convection forces.
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#2415
by
TheTraveller
on 09 Feb, 2017 19:00
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It seems you got a problem with the fact that the wave will more and more reflected at the sidewall instead of the endplate when the small diameter is below the cutoff diameter because your spreadsheet can't calculate this situation?? What else is the problem where exactly the reflection take place?
There is more than one way to overcome this problem using the well known equations.
I explaned the basic ideas I use in the past several times.
No problem at all. The reduced small end plate eddy currents vs the small end side wall eddy currents SHOUT OUT there is LESS Rf energy reaching the small end plate. If you can't see the small end plate is in cutoff, ie less Rf energy reaching it, well there is little to discuss.
Of course there the eddy currents are smaller in this case because of the sine / cosine switch to there hyperbolic version at the magic diameter, but the wave function have to satisfy the boundery conditions. Again what is the problem when the wave is refected at the sidewall rather than at the endplate?
Think of a photon with diameter of a ball equal to the cutoff diameter (yes crude analogy 
) which will reflected in a cone. What's the problem if there is no endplate?
So you accept Roger's 0.82 rule works to maintain a higher eddy current / energy hitting the small and plate than hitting the small end side wall eddy current ring? This is critical.
Now factor in differential end plate radiation pressure, that FEKO can't simulate. To do that you need to use the SPR Force equation and especially the Df equation, which again FEKO can't simulate.
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#2416
by
X_RaY
on 09 Feb, 2017 19:04
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It seems you got a problem with the fact that the wave will more and more reflected at the sidewall instead of the endplate when the small diameter is below the cutoff diameter because your spreadsheet can't calculate this situation?? What else is the problem where exactly the reflection take place?
There is more than one way to overcome this problem using the well known equations.
I explaned the basic ideas I use in the past several times.
No problem at all.
The FEKO reduced small end plate eddy currents vs the small end side wall eddy currents SHOUT OUT there is LESS Rf energy reaching the small end plate. If you can't see the small end plate is in cutoff, ie less Rf energy reaching it, well there is little to discuss.
FEKO is clearly showing any who will listen that Roger's 0.82 cutoff small end rule works. Yet you ignore the reducing small end plate diameter reducing (below cutoff) eddy current data that FEKO produces. Why?
Of course the eddy currents at the end plate are smaller in this case because of the sine / cosine of the standing wave is switching to there hyperbolic version at the magic diameter and the related field strength falls off faster beyond it, however the wave function have to satisfy the boundery conditions. Again what is the problem when the wave is refected at the sidewall rather than at the endplate?
Is it of interest were the losses take place?
If so, why?
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#2417
by
TheTraveller
on 09 Feb, 2017 19:09
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One interpretation of this is that Shaywer (who, although being the inventor of the EM Drive, has failed to report a single experiment performed in a vacuum chamber, although he has been at this for decades now) has measured an experimental artifact due to thermal convection heating of the end plate.
EW has clearly shown and stated there IS NO FORCE GENERATION DIFFERENCE BETWEEN ATMO AND VAC. You did read their peer reviewed paper?
As the heating of the end plates, sorry but neither SPR's data nor the EW data supports your statement. Care to provide the data that supports your statement?
BTW SPR has measured a static force with the thruster vertical, which eliminates thermal heating effecting the results as attached. I'm surprised you are unaware of that data?
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#2418
by
Rodal
on 09 Feb, 2017 19:09
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#2419
by
TheTraveller
on 09 Feb, 2017 19:13
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It seems you got a problem with the fact that the wave will more and more reflected at the sidewall instead of the endplate when the small diameter is below the cutoff diameter because your spreadsheet can't calculate this situation?? What else is the problem where exactly the reflection take place?
There is more than one way to overcome this problem using the well known equations.
I explaned the basic ideas I use in the past several times.
No problem at all.
The FEKO reduced small end plate eddy currents vs the small end side wall eddy currents SHOUT OUT there is LESS Rf energy reaching the small end plate. If you can't see the small end plate is in cutoff, ie less Rf energy reaching it, well there is little to discuss.
FEKO is clearly showing any who will listen that Roger's 0.82 cutoff small end rule works. Yet you ignore the reducing small end plate diameter reducing (below cutoff) eddy current data that FEKO produces. Why?
Of course the eddy currents at the end plate are smaller in this case because of the sine / cosine of the standing wave is switching to there hyperbolic version at the magic diameter and the related field strength falls off faster beyond it, but the wave function have to satisfy the boundery conditions. Again what is the problem when the wave is refected at the sidewall rather than at the endplate?
Is it of interest were the losses take place?
If so, why?
Not much reason to design a thruster where the small end energy is thermalised in the eddy current ring at the small end of the side wall.
The goal is to get the photons to transfer momentum into the small end plate and not into the eddy current ring at the cutoff end of the small end eddy current ring. That requires the small end plate to operate ABOVE cutoff.
) which will reflected in a cone. What's the problem if there is no endplate?