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#3320 by PotomacNeuron on 23 May, 2018 14:19
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Tajmar教授的腔体模态与杨涓教授的一致，极有可能是TE011模态，推力方向易出现180°反转。要确认推力是否来自腔体本身，可以采用对比法，将腔体替换成负载，看看是否依然存在推力，这个方法很简单
Translation:
Prof. Tajmar's cavity mode is consistent with Prof. Yang's, most likely TE011. The direction of thrust seems to reverse when the cavity is flipped 180°. To confirm whether the thrust comes from the cavity itself, you can use a comparative method by replacing the cavity with the load and see if the thrust still exists. This method is very simple.
Your translation mistranslated one sentence,QuoteTE011模态，推力方向易出现180°反转
TE011. The direction of thrust seems to reverse when the cavity is flipped 180°.
It should be: TE011 mode. The direction of thrust (of which) tends to reverse 180° (by itself due to some subtle changes of its environment/configuration etc).
Words in parentheses are mine. Oyzw's statement is consistent with what Yang and collegues found in their experiment, that the thrust direction was 180° from that from Shawyer's and their own theoretic or simulation work. -
#3321 by TheTraveller on 24 May, 2018 06:21
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This is the VNA sweep that looks for resonant rtn loss dips. Note how far down is the 1.865GHz dip when compared to the others. I have identified the modes of the other dips but not the 1.865GHz dip. A 55dB dip is not real especially when not confirmed by COMSOL or other such resonance analysis.
This suggests Tajmar was exciting a resonant coupler and not a resonant cavity mode.
Thus it is very likely little Rf energy entered the cavity and any that did could not excite a resonant mode.
I'm sure others here can take the EW cavity dimensions that Tajmar replicated, minus the EW dielectric and search for the resonant mode he excited at 1.865GHz?
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#3322 by TheTraveller on 24 May, 2018 08:28
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Paul March (then head EW engineer) did a scan of the cavity minus dielectrics. Resonant mode, with best Q was TE012, 2.167GHz, 3.85mN/kWrf
This is public info so why did Tajmar use a freq that was not cavity mode resonant & was not the highest Q?
Lorentz was measured & applied.
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#3323 by Monomorphic on 24 May, 2018 11:27
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I'm sure others here can take the EW cavity dimensions that Tajmar replicated, minus the EW dielectric and search for the resonant mode he excited at 1.865GHz?
This was already done by Frank Davies at NASA. COMSOL was used and TE212 found at 1880 Mhz (1.88 Ghz). I am assuming that is the mode as it is the closest to 1865 Mhz (1.865 Ghz).
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#3324 by Monomorphic on 24 May, 2018 11:32
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Another thing to note is the mode Tajmar claims is TM212 at 1971 Mhz (1.971 Ghz) was identified as Tx3xx by NASA using COMSOL.
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#3325 by PotomacNeuron on 24 May, 2018 11:45
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Paul March (then head EW engineer) did a scan of the cavity minus dielectrics. Resonant mode, with best Q was TE012, 2.167GHz, 3.85mN/kWrf
This is public info so why did Tajmar use a freq that was not cavity mode resonant & was not the highest Q?
Lorentz was measured & applied.
Those photos seems are about EW's 2014 paper. Their way of measuring Lorentz force was by replacing the cavity with a dummy load. However, the grounding schemes and lead configurations between the cavity exp and the dummy load exp were different, thus ground loop DC current were different, thus their way of measuring Lorentz force did not work. This was the main point of our 2015 arxiv paper, which was cited by Tajmar in his most recent paper. -
#3326 by TheTraveller on 24 May, 2018 12:09
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I'm sure others here can take the EW cavity dimensions that Tajmar replicated, minus the EW dielectric and search for the resonant mode he excited at 1.865GHz?
This was already done by Frank Davies at NASA. COMSOL was used and TE212 found at 1880 Mhz (1.88 Ghz). I am assuming that is the mode as it is the closest to 1865 Mhz (1.865 Ghz).
Jamie,
That analysis was with a dielectric at the small end. The mode was TE012.
Tajmar did not use a dielectric. -
#3327 by TheTraveller on 24 May, 2018 12:16
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Paul March (then head EW engineer) did a scan of the cavity minus dielectrics. Resonant mode, with best Q was TE012, 2.167GHz, 3.85mN/kWrf
This is public info so why did Tajmar use a freq that was not cavity mode resonant & was not the highest Q?
Lorentz was measured & applied.
Those photos seems are about EW's 2014 paper. Their way of measuring Lorentz force was by replacing the cavity with a dummy load. However, the grounding schemes and lead configurations between the cavity exp and the dummy load exp were different, thus ground loop DC current were different, thus their way of measuring Lorentz force did not work. This was the main point of our 2015 arxiv paper, which was cited by Tajmar in his most recent paper.
What Paul did was to remove the cavity, replacing it with a dummy load at the same location, moving nothing else.
This discussion is about Tajmar exciting his cavity at a freq it was not resonant at.
If you have cavity resonant data that supports a resonant mode at 1.865GHz for the cavity without a dielectric please post it. -
#3328 by Monomorphic on 24 May, 2018 12:18
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That analysis was with a dielectric at thr small end.
Tajmar did not use a dielectric.
This analysis does not use a dialectric. It comes from Frustum Modes Overview 2A, which is without dialectric. That is discussed here: https://forum.nasaspaceflight.com/index.php?topic=38203.1680
I have also confirmed this analysis long ago with FEKO. No dialectric.
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#3329 by TheTraveller on 24 May, 2018 12:36
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That analysis was with a dielectric at thr small end.
Tajmar did not use a dielectric.
This analysis does not use a dialectric. It comes from Frustum Modes Overview 2A, which is without dialectric. That is discussed here: https://forum.nasaspaceflight.com/index.php?topic=38203.1680
I have also confirmed this analysis long ago with FEKO. No dialectric.
Jamie,
1.8806 GHz at TE012 with 2 dielectric discs is the data Paul shared.
Here is a phone image of his slide. Apologies for the poor image quality.
I can't find any non dielectric resonant mode at 1.865GHz. Can you?
Plus the way too low VNA rtn loss of -55dB strongly suggests it is a self resonant coupler freq.
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#3330 by PotomacNeuron on 24 May, 2018 12:43
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Paul March (then head EW engineer) did a scan of the cavity minus dielectrics. Resonant mode, with best Q was TE012, 2.167GHz, 3.85mN/kWrf
This is public info so why did Tajmar use a freq that was not cavity mode resonant & was not the highest Q?
Lorentz was measured & applied.
Those photos seems are about EW's 2014 paper. Their way of measuring Lorentz force was by replacing the cavity with a dummy load. However, the grounding schemes and lead configurations between the cavity exp and the dummy load exp were different, thus ground loop DC current were different, thus their way of measuring Lorentz force did not work. This was the main point of our 2015 arxiv paper, which was cited by Tajmar in his most recent paper.
What Paul did was to remove the cavity, replacing it with a dummy load at the same location, moving nothing else.
True but the grounding scheme and lead configuration were also changed.QuoteThis discussion is about Tajmar exciting his cavity at a freq it was not resonant at.
If you have cavity resonant data that supports a resonant mode at 1.865GHz for the cavity without a dielectric please post it.
I knew. I posted the unrelated reply because you added an unrelated statement to the discussion, "Lorentz was measured & applied." I just do not want people to be misled into believing that "3.85mN/kWrf" was real. -
#3331 by Monomorphic on 24 May, 2018 12:57
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1,880.6 GHz at TE012 with 2 dielectric discs is the data Paul shared.
I can't find any non dielectric resonant mode at 1.865GHz. Can you?
Plus the way too low VNA rtn loss of -55dB strongly suggests it is a self resonant coupler freq.
Please check what I wrote again: " TE212 found at 1880 Mhz (1.88 Ghz)" I did not write TE012 at 1.88 Ghz.
However, I think you could be correct about them exciting a resonant coupler and not the cavity as if you look closely, there is a RL dip at 1.88 Ghz, where we would expect TE212. There shouldn't be anything at 1.865 Ghz.
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#3332 by TheTraveller on 24 May, 2018 13:29
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1,880.6 GHz at TE012 with 2 dielectric discs is the data Paul shared.
I can't find any non dielectric resonant mode at 1.865GHz. Can you?
Plus the way too low VNA rtn loss of -55dB strongly suggests it is a self resonant coupler freq.
Please check what I wrote again: " TE212 found at 1880 Mhz (1.88 Ghz)" I did not write TE012 at 1.88 Ghz.
However, I think you could be correct about them exciting a resonant coupler and not the cavity as if you look closely, there is a RL dip at 1.88 Ghz, where we would expect TE212. There shouldn't be anything at 1.865 Ghz.
Jamie,
I have identified modes for the 4 rtn loss dips to the right of that massive -55dB rtn loss dip. But nothing for 1.865GHz.
Agree the little rtn loss dip is probably TE212.
Should add that Tajmar said he did not know what the excited mode was. -
#3333 by SeeShells on 24 May, 2018 13:30
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Just got on this morning reading these posts and I must say you both seemed to have shown why the Tajmar's team only showed Lorentz forces. Very nice detective work.1,880.6 GHz at TE012 with 2 dielectric discs is the data Paul shared.
I can't find any non dielectric resonant mode at 1.865GHz. Can you?
Plus the way too low VNA rtn loss of -55dB strongly suggests it is a self resonant coupler freq.
Please check what I wrote again: " TE212 found at 1880 Mhz (1.88 Ghz)" I did not write TE012 at 1.88 Ghz.
However, I think you could be correct about them exciting a resonant coupler and not the cavity as if you look closely, there is a RL dip at 1.88 Ghz, where we would expect TE212. There shouldn't be anything at 1.865 Ghz.
My Best,
Shell
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#3334 by TheTraveller on 24 May, 2018 13:46
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Just got on this morning reading these posts and I must say you both seemed to have shown why the Tajmar's team only showed Lorentz forces. Very nice detective work.1,880.6 GHz at TE012 with 2 dielectric discs is the data Paul shared.
I can't find any non dielectric resonant mode at 1.865GHz. Can you?
Plus the way too low VNA rtn loss of -55dB strongly suggests it is a self resonant coupler freq.
Please check what I wrote again: " TE212 found at 1880 Mhz (1.88 Ghz)" I did not write TE012 at 1.88 Ghz.
However, I think you could be correct about them exciting a resonant coupler and not the cavity as if you look closely, there is a RL dip at 1.88 Ghz, where we would expect TE212. There shouldn't be anything at 1.865 Ghz.
My Best,
Shell
Shell,
Thanks.
As we both know, Rf microwave engineering is not easy. Tajmar needs a well experienced microwave engineering on his team that would instantly tell them a -55dB rtn loss on a VNA scan is false.
Plus where is the Smith Chart showing a nice round circle, crossing the centre line at 50 ohm impedance and showing equal amounts of L and C energy on both sides of resonance? -
#3335 by flux_capacitor on 24 May, 2018 14:08
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McCulloch's opinion of the media reaction to the Tajmar EmDrive test:
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#3336 by SeeShells on 24 May, 2018 14:12
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McCulloch's opinion of the media reaction to the Tajmar EmDrive test:
A farmer, an engineer, and a physicist were all asked to build a chicken coop. The farmer says, “Well, last time I had so many chickens and my coop was so and so big and this time I have this many chickens so I’ll make it this much bigger and that oughtta work just fine.” The engineer tackles the problem by surveying, costing materials, reading up on chickens and their needs, writing down a bunch of equations to minimize the cost per chicken, taking into account the lay of the land and writing a computer program to solve the problem. The physicist looks at the problem and says, “Let’s start by assuming a spherical chicken in a vacuum...”. -
#3337 by flux_capacitor on 24 May, 2018 14:26
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Paul March (then head EW engineer) did a scan of the cavity minus dielectrics. Resonant mode, with best Q was TE012, 2.167GHz, 3.85mN/kWrf
This is public info so why did Tajmar use a freq that was not cavity mode resonant & was not the highest Q?
Lorentz was measured & applied.
Those photos seems are about EW's 2014 paper. Their way of measuring Lorentz force was by replacing the cavity with a dummy load. However, the grounding schemes and lead configurations between the cavity exp and the dummy load exp were different, thus ground loop DC current were different, thus their way of measuring Lorentz force did not work. This was the main point of our 2015 arxiv paper, which was cited by Tajmar in his most recent paper.
What Paul did was to remove the cavity, replacing it with a dummy load at the same location, moving nothing else.
True but the grounding scheme and lead configuration were also changed.QuoteThis discussion is about Tajmar exciting his cavity at a freq it was not resonant at.
If you have cavity resonant data that supports a resonant mode at 1.865GHz for the cavity without a dielectric please post it.
I knew. I posted the unrelated reply because you added an unrelated statement to the discussion, "Lorentz was measured & applied." I just do not want people to be misled into believing that "3.85mN/kWrf" was real.
White et al. (2017) in "Measurement of Impulsive Thrust from a Closed Radio-Frequency Cavity in Vacuum", Journal of Propulsion and Power, 33(4), part C "Vacuum campaign", section 8 "Error Sources", point 3 page 838:
"The third error is magnetic interaction, which has the potential for a false positive resulting from dc currents in power cables interacting during test article operation with ambient magnetic fields (e.g., local Earth field, magnetic damper) to generate a torque displacement on the pendulum. All dc power cables are a twisted pair or twisted shielded pair to minimize magnetic interaction. The test article is tested in forward, reverse, and null thrust orientations, but dc power cable routing and orientation is the same for all three configurations (power cables come in from the top of the test article), meaning any false positives will be the same magnitude and polarity for all three tests. This is not observed during the test campaign."
Eagleworks did not address the potential issue of DC ground loops, but their wires and electronics being fixed, such currents would have been the same whatever the cavity direction, so they would have been detected and could have been quantified if they occurred and affected the cavity behavior during forward and reverse tests. In such two tests, the grounding scheme was the same. -
#3338 by meberbs on 24 May, 2018 14:51
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I am disappointed.
Just got on this morning reading these posts and I must say you both seemed to have shown why the Tajmar's team only showed Lorentz forces. Very nice detective work.1,880.6 GHz at TE012 with 2 dielectric discs is the data Paul shared.
I can't find any non dielectric resonant mode at 1.865GHz. Can you?
Plus the way too low VNA rtn loss of -55dB strongly suggests it is a self resonant coupler freq.
Please check what I wrote again: " TE212 found at 1880 Mhz (1.88 Ghz)" I did not write TE012 at 1.88 Ghz.
However, I think you could be correct about them exciting a resonant coupler and not the cavity as if you look closely, there is a RL dip at 1.88 Ghz, where we would expect TE212. There shouldn't be anything at 1.865 Ghz.
My Best,
Shell
Monomorphic and SeeShells, you have demonstrated with your experiments a commitment to the scientific method. But now on the prompting of one poster here who has repeatedly failed at entry-level physics, you jump on an explanation without any empirical evidence.
Never mind that no one has ever measured a large peak in any experiment reported here due to a "resonant coupler."
Never mind that it makes no sense for such a coupler to have such a high Q despite all the difficulty that everyone here knows goes into making high Q systems.
Never mind that they have a 3 stub tuner keeping more energy in the RF cavity, leading to lower reflections, so they should have a deep trough at the tuned frequency.
Never mind that TT claimed "not confirmed by COMSOL" in a post where he had attached a picture of the COMSOL simulation they did.
You apparently are giving up on science, and taking the path of jumping on the first explanation you are given that contradicts an experiment with a result you don't like.McCulloch's opinion of the media reaction to the Tajmar EmDrive test:
Is everyone who has looked at the emDrive losing their minds? McCulloch has seemed reasonable before, but unless this was accompanied by an actual detailed explanation of a problem with the experiment, this comic is the equivalent of him plugging his ears and loudly saying "LALALA I CAN'T HEAR YOU."
His comparison of this experiment to a dead chicken rather than a live one is significantly worse than any media treatment of this I have seen. -
#3339 by flux_capacitor on 24 May, 2018 15:06
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On the contrary, I enjoyed McCulloch's cartoon. He has a good sense of humor.
Would like a sound comment from X_Ray about that 55dB dip of the S11 return loss.