-
#2020 by Notsosureofit on 20 Jan, 2016 16:29
-
Digging through my vast (ok ... half vast) library of old physics books, I found (unread) "Systems with Small Dissipation" by Braginsky, Mitrofanov and Panov. ISBN 0-226-07073-5
Good chapters on superconducting cavity resonators and Dielectric filled.
My main interest is in chap. IV, "Self-Excited Oscillators".
There is a small section (11.) on Gravitational Antennae. -
#2021 by Notsosureofit on 20 Jan, 2016 16:50
-
Digging through my vast (ok ... half vast) library of old physics books, I found (unread) "Systems with Small Dissipation" by Braginsky, Mitrofanov and Panov. ISBN 0-226-07073-5
That's a great Russian book, the translation to English was edited by the great Kip Thorne, advisor to the movie Interstellar
Good chapters on superconducting cavity resonators and Dielectric filled.
My main interest is in chap. IV, "Self-Excited Oscillators".
There is a small section (11.) on Gravitational Antennae.
do you have the translation to English or are you reading it in Russian ?
Professor of Physics at CalTech
English, haven't HAD to read any Russian since my language exam !
-
#2022 by Rodal on 20 Jan, 2016 17:00
-
...English, haven't HAD to read any Russian since my language exam !
Remember those days when being able to read Russian technical articles was "de rigueur" for anybody working in Aerospace, Physics or Science !
-
#2023 by Notsosureofit on 20 Jan, 2016 17:05
-
#2024 by Rodal on 20 Jan, 2016 17:10
-
Here's a google ref
https://www.researchgate.net/profile/Jerzy_Krupka2/publication/228347721_Frequency_domain_complex_permittivity_measurements_at_microwave_frequencies/links/02e7e51cf27f5db8cd000000.pdf
Thanks, it is an overview of measurement techniques, but no table of values for different media
Has values for yttrium iron garnet -
#2025 by Notsosureofit on 20 Jan, 2016 17:20
-
Here's a google ref
https://www.researchgate.net/profile/Jerzy_Krupka2/publication/228347721_Frequency_domain_complex_permittivity_measurements_at_microwave_frequencies/links/02e7e51cf27f5db8cd000000.pdf
Thanks, it is an overview of measurement techniques, but no table of values for different media
Has values for yttrium iron garnet
Von Hippel used to make those kind of measurements for the "Model" atmosphere. He wanted to set up a post-doc to combine my acoustic technique w/ his setup. He had an "idea" (didn't give me details) , but couldn't get funding. (Would have meant 5 simultaneous equations !) Nice tea and cookies though !
Hmm.. http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA288986
-
#2026 by Rodal on 20 Jan, 2016 17:28
-
Here's a google ref
https://www.researchgate.net/profile/Jerzy_Krupka2/publication/228347721_Frequency_domain_complex_permittivity_measurements_at_microwave_frequencies/links/02e7e51cf27f5db8cd000000.pdf
Thanks, it is an overview of measurement techniques, but no table of values for different media
Has values for yttrium iron garnet
Von Hippel used to make those kind of measurements for the "Model" atmosphere. He wanted to set up a post-doc to combine my acoustic technique w/ his setup. He had an "idea" (didn't give me details) , but couldn't get funding. (Would have meant 5 simultaneous equations !) Nice tea and cookies though !
Extremely impressed !
I only knew Von Hippel from reading his books, (from his lab came the research and people leading to the transistor and other fundamental material science breakthoughs ), while you knew him personally !
-
#2027 by Notsosureofit on 20 Jan, 2016 17:38
-
Here's a google ref
https://www.researchgate.net/profile/Jerzy_Krupka2/publication/228347721_Frequency_domain_complex_permittivity_measurements_at_microwave_frequencies/links/02e7e51cf27f5db8cd000000.pdf
Thanks, it is an overview of measurement techniques, but no table of values for different media
Has values for yttrium iron garnet
Von Hippel used to make those kind of measurements for the "Model" atmosphere. He wanted to set up a post-doc to combine my acoustic technique w/ his setup. He had an "idea" (didn't give me details) , but couldn't get funding. (Would have meant 5 simultaneous equations !) Nice tea and cookies though !
Extremely impressed !
I only knew Von Hippel from reading his books, (from his lab came the research and people leading to the transistor and other fundamental material science breakthoughs ), while you knew him personally !
Not well, as it turned out, but personally, enough to get a good impression !
"Von Hippel laments that ‘the securing of funds for
the creation and maintenance of facilities as well as
for the salaries of staff and students falls also to the
unhappy lot of the research professor in charge’. "
-
#2028 by Rodal on 20 Jan, 2016 17:42
-
Update on FEKO.
Lite will not run my frustum and I've heard others telling me the same thing.
Also: (quote) Full FEKO evaluation license valid for 45 days is no longer available. Only the FEKO LITE version which is a restricted version is available to download for free.(end quote)
Nice user interface and I was able to model my frustum and the change I wanted quite quickly but that's where it stopped. They want you to buy the full version and I'm waiting for some pricing.
Shell
"The other" thread is now showing dielectric insert designs thanks to FEKO (while in this thread we are just talking about dielectrics ):
https://www.reddit.com/r/EmDrive/comments/41slhi/the_islandplaya_virtual_em_drive/
This includes a FEKO a S-parameter plot (never seen an S-parameter plot produced by Meep users ), including calculation of the frequency bandwidth
Acknowledgement to Island Playa and FEKO for the images below
-
#2029 by rfmwguy on 20 Jan, 2016 17:45
-
#2030 by rfmwguy on 20 Jan, 2016 18:23
-
Notice something wrong with the S- parameter plot Doc? Might be a good idea not to praise it too muchUpdate on FEKO.
Lite will not run my frustum and I've heard others telling me the same thing.
Also: (quote) Full FEKO evaluation license valid for 45 days is no longer available. Only the FEKO LITE version which is a restricted version is available to download for free.(end quote)
Nice user interface and I was able to model my frustum and the change I wanted quite quickly but that's where it stopped. They want you to buy the full version and I'm waiting for some pricing.
Shell
This NSF thread better up its game, as "the other" thread continues to make rapid progress by leaps and bounds, now modeling dielectric insert designs thanks to FEKO (while in this thread we are just talking about dielectrics ):
https://www.reddit.com/r/EmDrive/comments/41slhi/the_islandplaya_virtual_em_drive/
Look at how Island Playa (acknowledged below) was able to readily produce with FEKO a S-parameter plot (never seen anything like that produced by Meep users ), including calculation of the frequency bandwidth
Acknowledgement to Island Playa for the images below, Excellent work !
-
#2031 by sghill on 20 Jan, 2016 18:27
-
Doc, has anyone done the math to show what the equivalent force would be at 1kW using Einstein's cylinder shape? Also, are there any reasons to assume an asymmetrical shape might not add to the effect?Einsteins paper...posted elsewhere, linked here as well. A cylinder in space and imparted motion due to radiation applied:
http://einsteinpapers.press.princeton.edu/vol2-trans/214?ajax
This was precisely the point made by NSF user WarpTech, (Todd we miss ya ) in classic exchanges he had in these threads with NSF user DeltaMass (we miss you too ). Unfortunately the EM Drive's claimed self-acceleration does not appear to be explainable on this basis because of...the relatively puny energy change involved in the EM Drive cannot be used to justify the claimed "anomalous force" (off by orders of magnitude...)
Back to the whiteboard and keep your eyes on the Notsosureofit hypothesis, who remains here (from time to time )...
I remember that exchange, and I still find it the most compelling theory for EMDrive operation- in particular as it also allowed for the warping measured at EW that set off the whole press feeding frenzy last spring. And no CoM violation!
Rodal, would you mind pointing me to the discussion of the energy change problem (that it was too small) that closed off that theory?
The entire reason we use a resonant chamber for anything is to get orders of magnitude more effect from small inputs.
-
#2032 by Rodal on 20 Jan, 2016 19:01
-
Doc, has anyone done the math to show what the equivalent force would be at 1kW using Einstein's cylinder shape? Also, are there any reasons to assume an asymmetrical shape might not add to the effect?Einsteins paper...posted elsewhere, linked here as well. A cylinder in space and imparted motion due to radiation applied:
http://einsteinpapers.press.princeton.edu/vol2-trans/214?ajax
This was precisely the point made by NSF user WarpTech, (Todd we miss ya ) in classic exchanges he had in these threads with NSF user DeltaMass (we miss you too ). Unfortunately the EM Drive's claimed self-acceleration does not appear to be explainable on this basis because of...the relatively puny energy change involved in the EM Drive cannot be used to justify the claimed "anomalous force" (off by orders of magnitude...)
Back to the whiteboard and keep your eyes on the Notsosureofit hypothesis, who remains here (from time to time )...
I remember that exchange, and I still find it the most compelling theory for EMDrive operation- in particular as it also allowed for the warping measured at EW that set off the whole press feeding frenzy last spring. And no CoM violation!
Rodal, would you mind pointing me to the discussion of the energy change problem (that it was too small) that closed off that theory?
The entire reason we use a resonant chamber for anything is to get orders of magnitude more effect from small inputs.
Mmm. I would not call the discussion "closed off" but unfortunately ended by the fact that DeltaMass is not longer a NSF user and the fact that at about that time WarpTech stopped contributing to these threads.
Concerning finding those classic discussions, it is a matter of searching for WarpTech, (and or DeltaMass), EM Drive, NSF, energy with Google Advanced Search. I don't recall specifically in what thread and at what time those discussions took place. -
#2033 by rfmwguy on 20 Jan, 2016 19:03
-
Nope, wrong concern. Links or credit are no problem. See the problem on the S11 model/plot?
Notice something wrong with the S- parameter plot Doc? Might be a good idea not to praise it too muchUpdate on FEKO.
Lite will not run my frustum and I've heard others telling me the same thing.
Also: (quote) Full FEKO evaluation license valid for 45 days is no longer available. Only the FEKO LITE version which is a restricted version is available to download for free.(end quote)
Nice user interface and I was able to model my frustum and the change I wanted quite quickly but that's where it stopped. They want you to buy the full version and I'm waiting for some pricing.
Shell
This NSF thread better up its game, as "the other" thread continues to make rapid progress by leaps and bounds, now modeling dielectric insert designs thanks to FEKO (while in this thread we are just talking about dielectrics ):
https://www.reddit.com/r/EmDrive/comments/41slhi/the_islandplaya_virtual_em_drive/
Look at how Island Playa (acknowledged below) was able to readily produce with FEKO a S-parameter plot (never seen anything like that produced by Meep users ), including calculation of the frequency bandwidth
Acknowledgement to Island Playa for the images below, Excellent work !
It is NSF policy that all images from other Internet sources should be generously credited and acknowledged to the authors of the intellectual property. I hope you are not now discouraging NSF users in this thread to disregard following this NSF policy.
Specifically, at the start of this thread you wrote:Quote from: RMFWGUYPlease acknowledge the authors and respect copyrights.
FEKO is a great program, by a Professor in Germany, do you have some specific criticism against the way that FEKO calculates the S-parameter?
(edit) - Suffice it to say, this is one of the worst examples of cavity modeling I've seen is a long, long time. Anybody who wants to know why, they can PM me. All I'm going to say is the model is severely flawed and its not the software best I can tell, its the inputs. Any Te & Tm modal analysis would be a waste of time...don't even bother is my opinion. Think others already picked up on this. -
#2034 by Notsosureofit on 20 Jan, 2016 19:15
-
Haven't fully followed up on those complex quantities. (good excuse for a "secret sauce")
Edit: (just made it to computer) Yes ... your edit is correct. Note all real gasses will have some imaginary components which will lower (?) the Q. By how much is a question.
Just got back again.. (troublesome vacuum equipment, as per usual)
Anyway, to continue, as the dielectric constant is increased, the frequency of the resonances decreases so the size of the cavity decreases for the same frequency and the Q decreases for the same surface conductivity as well as by the loss tangent of the dielectric. That may be close to breakeven or a slight loss ? -
#2035 by Star One on 20 Jan, 2016 19:34
-
Quickly all build us a probe to reach the new planet nine & then one for Tabby's star whilst you're at it.
-
#2036 by Rodal on 20 Jan, 2016 19:51
-
Haven't fully followed up on those complex quantities. (good excuse for a "secret sauce")
Edit: (just made it to computer) Yes ... your edit is correct. Note all real gasses will have some imaginary components which will lower (?) the Q. By how much is a question.
Just got back again.. (troublesome vacuum equipment, as per usual)
Anyway, to continue, as the dielectric constant is increased, the frequency of the resonances decreases so the size of the cavity decreases for the same frequency and the Q decreases for the same surface conductivity as well as by the loss tangent of the dielectric. That may be close to breakeven or a slight loss ?
Yes, as the dielectric constant is increased the natural frequency decreases, for example for NASA, the natural frequency decreased from around 2.16 GHz to around 1.9 GHz, less than 15% decrease
The Q also decreases, as the result of the loss tangent. But here observe what we learned from NASA: it was much better to use HDPE as a dielectric than to use Neoprene rubber as a dielectric. Although Neoprene rubber had a larger real part of the permittivity, Neoprene has also a much larger tan delta which resulted in lower Q and much lower "anomalous force".
Using HDPE (and PTFE which was almost as good, but HDPE appears better) they decreased the natural frequency just a little (less than 15) with minimal decrease in Q (they got Q=20,000) because HDPE has such a small value of tan delta.
Also, of course the size of the dielectric plays a role. They amount of volume taken by the HDPE is relatively small and placed at the small end.
That's regarding polymers as a dielectric.
___________________________
I don't have the tan delta for Ammonia (let me know if you find a value), but strictly going on the fact that Ammonia is used so successfully in Masers (of course due to emitting at 24 GHz) it seems that Ammonia is certainly worth a try -
#2037 by RFPlumber on 20 Jan, 2016 19:51
-
Update on FEKO.
Lite will not run my frustum and I've heard others telling me the same thing.
Also: (quote) Full FEKO evaluation license valid for 45 days is no longer available. Only the FEKO LITE version which is a restricted version is available to download for free.(end quote)
Nice user interface and I was able to model my frustum and the change I wanted quite quickly but that's where it stopped. They want you to buy the full version and I'm waiting for some pricing.
Shell
There are other programs beside FEKO.
RFPlumber has access to COMSOL and has used it effectively. COMSOL can readily calculate the natural frequencies and mode shapes of cavities with asymmetrically placed dielectrics. Also COMSOL can readily display numerical values of the electromagnetic fields in SI units for a 3-D truncated cone that is readily digested and understood.
Sorry, I am not likely to be spending much more time on this effort other than to write a summary paper. At this point the "EmDrive" at DIY level is obviously just an RF playground. There is literally zero credible evidence that any experiment to date has produced any abnormal force anywhere above the noise level. Note the word credible above, as it is simply unbelievable to what extremes people are willing to bend and massage the facts in order tokeep the illusion alive, stay in business, get more fundingwhatever their agenda is. This was a fun exercise in RF techniques, but even more so this was just another sad encounter with human nature. -
#2038 by Notsosureofit on 20 Jan, 2016 20:05
-
Haven't fully followed up on those complex quantities. (good excuse for a "secret sauce")
Edit: (just made it to computer) Yes ... your edit is correct. Note all real gasses will have some imaginary components which will lower (?) the Q. By how much is a question.
Just got back again.. (troublesome vacuum equipment, as per usual)
Anyway, to continue, as the dielectric constant is increased, the frequency of the resonances decreases so the size of the cavity decreases for the same frequency and the Q decreases for the same surface conductivity as well as by the loss tangent of the dielectric. That may be close to breakeven or a slight loss ?
Yes, as the dielectric constant is increased the natural frequency decreases, for example for NASA, the natural frequency decreased from around 2.16 GHz to around 1.9 GHz, less than 15% decrease
The Q also decreases, as the result of the loss tangent. But here observe what we learnt from NASA: it was much better to use HDPE as a dielectric than to use Neoprene rubber as a dielectric. Although Neoprene rubber had a larger real part of the permittivity, Neoprene has also a much larger tan delta which resulted in lower Q and much lower "anomalous force".
Using HDPE (and PTFE which was almost as good, but HDPE appears better) they decreased the natural frequency just a little (less than 15) with minimal decrease in Q (they got Q=20,000) because HDPE has such a small value of tan delta.
Also, of course the size of the dielectric plays a role. They amount of volume taken by the HDPE is relatively small and placed at the small end.
That's regarding polymers as a dielectric.
___________________________
I don't have the tan delta for Ammonia (let me know if you find a value), but strictly going on the fact that Ammonia is used so successfully in Masers (of course due to emitting at 24 GHz) it seems that Ammonia is certainly worth a try
So the idea is to let the frequency fall (not a problem w/ a variable source) and optimize the thickness of (still got to look at that) the dielectric at the small end (I agree, that is the best position) using some dielectric w/ a minimum loss tangent. -
#2039 by Rodal on 20 Jan, 2016 20:15
-
I very much appreciate the fact that you spent your valuable time in this effort, and that you conducted your experiment and calculations in a very professional way.Update on FEKO.
Lite will not run my frustum and I've heard others telling me the same thing.
Also: (quote) Full FEKO evaluation license valid for 45 days is no longer available. Only the FEKO LITE version which is a restricted version is available to download for free.(end quote)
Nice user interface and I was able to model my frustum and the change I wanted quite quickly but that's where it stopped. They want you to buy the full version and I'm waiting for some pricing.
Shell
There are other programs beside FEKO.
RFPlumber has access to COMSOL and has used it effectively. COMSOL can readily calculate the natural frequencies and mode shapes of cavities with asymmetrically placed dielectrics. Also COMSOL can readily display numerical values of the electromagnetic fields in SI units for a 3-D truncated cone that is readily digested and understood.
Sorry, I am not likely to be spending much more time on this effort other than to write a summary paper. At this point the "EmDrive" at DIY level is obviously just an RF playground. There is literally zero credible evidence that any experiment to date has produced any abnormal force anywhere above the noise level. Note the word credible above, as it is simply unbelievable to what extremes people are willing to bend and massage the facts in order tokeep the illusion alive, stay in business, get more fundingwhatever their agenda is. This was a fun exercise in RF techniques, but even more so this was just another sad encounter with human nature.
If you ever have more time to spend in this area, your continued involvement will continue to be most appreciated
