Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1802951 times)

Offline X_RaY

  • Full Member
  • ****
  • Posts: 774
  • Germany
  • Liked: 993
  • Likes Given: 2144
... I am also more convinced by the theory that TE excitation is not possible...
The only reason why the TE mode has not been excited in the Meep software models run by aero is because aero has run Meep models using dipole antennas, as aero has explained, because he did not have a software means ready to simulate a loop antenna in Meep.  TE modes are more readily excited with a loop antenna, rather than a dipole antenna. X-Ray has suggested how to excite a TE mode with a dipole antenna but it requires to be done at a precise location and orientation which depends on the geometry.   

Theoretically there is no problem in exciting TE012 in the Yang/Shell actual fustrum geometry if suitable means are used.  NASA has reported practical problems exciting TE012 in their NASA report (http://www.libertariannews.org/wp-content/uploads/2014/07/AnomalousThrustProductionFromanRFTestDevice-BradyEtAl.pdf ).

Quote from: Brady et al
Prior to the TM211 evaluations, COMSOL analysis indicated that the TE012 was an effective thrust generation mode for the tapered cavity thruster being evaluated, so this mode was explored early in the evaluation process. Figure 22 shows a test run at the TE012 mode with an operating frequency of 1880.4 MHz. The measured quality factor was ~22,000, with a COMSOL prediction of 21,817. The measured power applied to the test article was measured to be 2.6 watts, and the (net) measured thrust was 55.4 micronewtons. With an input power of 2.6 watts, correcting for the quality factor, the predicted thrust is 50 micronewtons. However, since the TE012 mode had numerous other RF modes in very close proximity, it was impractical to repeatedly operate the system in this mode, so the decision was made to evaluate the TM211 modes instead

 Shawyer and TheTraveller report that Shawyer has excited TE012 and TE013 in Shawyer's EM Drives and so has Yang reported exciting the TE012 mode.

In a cylindrical waveguide, with planar wave fronts, it is simple to excite TE01 mode using a straight 1/4 lambda0 (external wavelength) stub antenna placed 1/4 lambdag (internal TE01 mode guide wavelength) away from an end plate.
Sorry, but that's wrong. Based on your drawing you want to excite the TE11.

TE01 and TE11 have very different guide wavelengths and thus different back plate to antenna spacing. As the external frequency is not changed, the 1/4 wave stud antenna length stays the same.

As an example for a waveguide of 200mm dia to be excited at TE01 at 2.45Ghz, the guide wavelength would be 0.1837m and for TE11 the guide wavelength would be 0.1310m. In each case the back plate to the antenna spacing would be 25% of the appropriate guide wavelength, so the excitation of the 2 modes requires a considerable difference in the antenna to the back plate spacing.
I have edit the post.
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1412830#msg1412830

Offline TheTraveller

The NASA and others would do it this way for example*.
YES its a loop in the right direction and at that position instead of a monopole  ---> TE01

*and of course there are other possibilities :)

EW use a side wall mounted loop antenna about 1.5 inches from the base to excite, I think it was, TM211 mode.
« Last Edit: 08/03/2015 06:49 PM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline X_RaY

  • Full Member
  • ****
  • Posts: 774
  • Germany
  • Liked: 993
  • Likes Given: 2144
The NASA and others would do it this way for example*.
YES its a loop in the right direction and at that position instead of a monopole  ---> TE01

*and of course there are other possibilities :)

EW use a side wall mounted loop antenna about 1.5 inches from the base to excite, I think it was, TM211 mode.

Again it will work, it's a question of the coupling factor (and how much energy you can put into the cavity).
I search for good solutions for such problems for over 10 years now. I do it with a well known Prof. of W engineering. I know what i am saying, believe it or not. If you like to do so, do it and measure and dont forget to post the results. OK?! I have no problem with that, its your turn

I am here to do good science only. Nothing else :) (don't like to "nitpicking" you!)
« Last Edit: 08/03/2015 07:15 PM by X_RaY »

Offline TheTraveller

I search for good solutions for such problems for over 10 years now. I do it with a well known Prof. of W engineering. I know what i am saying, believe it or not. If you like to do so, do it and measure and dont forget to post the results. OK?! I have no problem with that, its your turn

Can you please explain what bad and good coupling are in reference to an antenna design exciting a desired mode in a waveguide or resonant cavity?

The examples I have used are from microwave tech books. Are they incorrect or are there better ways and if so why are the better ways better?
« Last Edit: 08/03/2015 07:20 PM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline X_RaY

  • Full Member
  • ****
  • Posts: 774
  • Germany
  • Liked: 993
  • Likes Given: 2144
I search for good solutions for such problems for over 10 years now. I do it with a well known Prof. of W engineering. I know what i am saying, believe it or not. If you like to do so, do it and measure and dont forget to post the results. OK?! I have no problem with that, its your turn

Can you please explain what bad and good coupling are in reference to an antenna design exciting a desired mode in a waveguide or resonant cavity?

The examples I have used are from microwave tech books. Are they incorrect or are there better ways and if so why are the better ways better?
OK. Give me a specific problem. Which mode do you like to excite?

PS:These books are really helpful, also helpful is to have experience.
Theory is right most time, but to bring special solutions into practice is a different thing.

If you have a resonator with some antenna, put it onto a VNA and you will se what happens. First one have to think about the problem, look into the books, think about again and try an experiment based on your thinking result. Than make corrections. If you dont get good results, go back thinking, calculate and try an updated experiment again and again and again.. thats the way how scientists do it. It needs time but it works

There are so much things caused that an experiment fails, even the math is correct (good news: most time it is) change only one detail and do it again and so forth
« Last Edit: 08/03/2015 07:49 PM by X_RaY »

Offline TheTraveller

I search for good solutions for such problems for over 10 years now. I do it with a well known Prof. of W engineering. I know what i am saying, believe it or not. If you like to do so, do it and measure and dont forget to post the results. OK?! I have no problem with that, its your turn

Can you please explain what bad and good coupling are in reference to an antenna design exciting a desired mode in a waveguide or resonant cavity?

The examples I have used are from microwave tech books. Are they incorrect or are there better ways and if so why are the better ways better?
OK. Give me a specific problem. Which mode do you like to excite?

PS:These books are really helpful, also helpful is to have experience.
Theory is right most time, but to bring special solutions into practice is a different thing.

Lets start simple and excite TE01 in a 200mm diameter circular waveguide using 2.45GHz (121.9mm wavelength) as the external drive frequency.

I get 164.0mm as the cutoff wavelength and 182.2mm as the guide wavelength. To excite I would place the 30.5mm long stub antenna (1/4 wavelength of the external frequency) at a right angle to the side wall length axis and 45.6mm away from an end plate (1/4 of the guide wavelength).

Is there a better way?

« Last Edit: 08/03/2015 08:10 PM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline deltaMass

  • Full Member
  • ****
  • Posts: 955
  • A Brit in California
  • Liked: 671
  • Likes Given: 275
TheTraveller's post that graphed Shawyer's turnable velocity ( http://forum.nasaspaceflight.com/index.php?topic=37642.msg1411849#msg1411849 ) made me curious to see how that lined up with the "power off" event in the video ( http://www.emdrive.com/fullDMtest188.mpg ). Attached are my results.

To try to be consistent with TheTraveller's data, each 'rotation tick' is half of each line-separated segment on the turntable. There will be a small amount of drift from switching between one of the little black rods rotating around to another. The point's location on the time axis will also jitter a little, since I was only recording times with second resolution.
The plot is POSITION vs. TIME.
Here's some post-processing for velocity and acceleration. It could benefit from a better filter algorithm. But you get a rough idea. It doesn't make a lot of sense, does it?
« Last Edit: 08/03/2015 08:02 PM by deltaMass »

Offline TheTraveller

TheTraveller's post that graphed Shawyer's turnable velocity ( http://forum.nasaspaceflight.com/index.php?topic=37642.msg1411849#msg1411849 ) made me curious to see how that lined up with the "power off" event in the video ( http://www.emdrive.com/fullDMtest188.mpg ). Attached are my results.

To try to be consistent with TheTraveller's data, each 'rotation tick' is half of each line-separated segment on the turntable. There will be a small amount of drift from switching between one of the little black rods rotating around to another. The point's location on the time axis will also jitter a little, since I was only recording times with second resolution.
The plot is POSITION vs. TIME.
Here's some post-processing for velocity and acceleration. It could benefit from a better filter algorithm. But you get a rough idea. It doesn't make a lot of sense, does it?

It is what it is.

Will get much better data in around 2 months as my build should start in 6 weeks.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline deltaMass

  • Full Member
  • ****
  • Posts: 955
  • A Brit in California
  • Liked: 671
  • Likes Given: 275
It is what it is.
Good grief, man. Is that the best you can come up with?
It is, after all, a Stone Tablet of data handed down by your Guru.

Or do you recommend we do science by ignoring the data that doesn't fit our preconceptions?
« Last Edit: 08/03/2015 08:10 PM by deltaMass »

Offline TheTraveller

It is what it is.
Good grief, man. Is that the best you can come up with?
It is, after all, a Stone Tablet of data handed down by your Guru.

Or do you recommend we do science by ignoring the data that doesn't fit our preconceptions?

Does that include ignoring Shawyer's and Prof Yang's Force measurement data because you don't believe the group velocity is different at each end and therefore their data is rubbish and can't be trusted?

The rotary table data is what it is. Data is data. Looking at the time versus distance Blue curve it is clear the table was initially accelerating and then stopped accelerating when the power was removed.

BTW POSITION is DISTANCE. So the Dark Blue original plot is Distance moved (y) versus Time to do the move (x).

Just looked at how you massaged the Excel data to get those crap looking curves. Why did you do that? Did you think no one would look at your Excel spreadsheet?
« Last Edit: 08/03/2015 08:35 PM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline rfmwguy

  • EmDrive Builder (retired)
  • Senior Member
  • *****
  • Posts: 2165
  • Liked: 2681
  • Likes Given: 1124
There is growing evidence (I think) that TM is the critical mode and not TE. While I'm not trying to throw stones, it is the direction I am going with my theory.

http://processmodeling.org/theory/physics/kinetic.htm

<snip>

"The conclusion - The kinetic energy of the electron is identical to its magnetic energy."

<snip>

"6. General conclusion. - Kinetic energies are electromagnetic energies

Kinetic energies can, in certain conditions, be restructured (converted) into tangible particles and vice versa, tangible particle can be restructured into field ones, i.e. into kinetic energy.

Kinetic energy is conveyed from one object to another in the form of electromagnetic waves (photons)."

Offline Blaine

  • Member
  • Posts: 58
  • Spring Hill, KS
  • Liked: 45
  • Likes Given: 122
It is what it is.
Good grief, man. Is that the best you can come up with?
It is, after all, a Stone Tablet of data handed down by your Guru.

Or do you recommend we do science by ignoring the data that doesn't fit our preconceptions?

Does that include ignoring Shawyer's and Prof Yang's Force measurement data because you don't believe the group velocity is different at each end and therefore their data is rubbish and can't be trusted?

The rotary table data is what it is. Data is data. Looking at the time versus distance Blue curve it is clear the table was initially accelerating and then stopped accelerating when the power was removed.

BTW POSITION is DISTANCE. So the Dark Blue original plot is Distance moved (y) versus Time to do the move (x).

For the love of the EmDrive dude, please think...
Weird Science!

Offline deltaMass

  • Full Member
  • ****
  • Posts: 955
  • A Brit in California
  • Liked: 671
  • Likes Given: 275
I'd be pleased to read interpretations from someone capable of analysing the data.
In the interim, I'm pondering using a Savitzky-Golay filter or something simpler perhaps.

The raw data consists actually of a sequence t(x), where the x-values increment. What's required is a robust way to generate x(t). Suggestions welcome.

Best would be a way to do it inside Excel.
« Last Edit: 08/03/2015 09:00 PM by deltaMass »

Offline TheTraveller

There is growing evidence (I think) that TM is the critical mode and not TE. While I'm not trying to throw stones, it is the direction I am going with my theory.

http://processmodeling.org/theory/physics/kinetic.htm

<snip>

"The conclusion - The kinetic energy of the electron is identical to its magnetic energy."

<snip>

"6. General conclusion. - Kinetic energies are electromagnetic energies

Kinetic energies can, in certain conditions, be restructured (converted) into tangible particles and vice versa, tangible particle can be restructured into field ones, i.e. into kinetic energy.

Kinetic energy is conveyed from one object to another in the form of electromagnetic waves (photons)."

Both Shawyer and Prof Yang say TE mode delivers more Force.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline deltaMass

  • Full Member
  • ****
  • Posts: 955
  • A Brit in California
  • Liked: 671
  • Likes Given: 275
It is what it is.
Good grief, man. Is that the best you can come up with?
It is, after all, a Stone Tablet of data handed down by your Guru.

Or do you recommend we do science by ignoring the data that doesn't fit our preconceptions?

Does that include ignoring Shawyer's and Prof Yang's Force measurement data because you don't believe the group velocity is different at each end and therefore their data is rubbish and can't be trusted?

The rotary table data is what it is. Data is data. Looking at the time versus distance Blue curve it is clear the table was initially accelerating and then stopped accelerating when the power was removed.

BTW POSITION is DISTANCE. So the Dark Blue original plot is Distance moved (y) versus Time to do the move (x).

Just looked at how you massaged the Excel data to get those crap looking curves. Why did you do that? Did you think no one would look at your Excel spreadsheet?
I am quite tired of your aggressive, truculent tone. You come off like a teenager with an inferiority complex. Please cease and desist. It is unutterably tiresome how you flip into aggressive mode at the drop of a hat.

I already made it clear that this was very rough. I already made it clear that the filtering needs improvement. What you see as "massaging" is actually crude low-pass filtering.

Offline X_RaY

  • Full Member
  • ****
  • Posts: 774
  • Germany
  • Liked: 993
  • Likes Given: 2144
I search for good solutions for such problems for over 10 years now. I do it with a well known Prof. of W engineering. I know what i am saying, believe it or not. If you like to do so, do it and measure and dont forget to post the results. OK?! I have no problem with that, its your turn

Can you please explain what bad and good coupling are in reference to an antenna design exciting a desired mode in a waveguide or resonant cavity?

The examples I have used are from microwave tech books. Are they incorrect or are there better ways and if so why are the better ways better?
OK. Give me a specific problem. Which mode do you like to excite?

PS:These books are really helpful, also helpful is to have experience.
Theory is right most time, but to bring special solutions into practice is a different thing.

Lets start simple and excite TE01 in a 200mm diameter circular waveguide using 2.45GHz (121.9mm wavelength) as the external drive frequency.

I get 164.0mm as the cutoff wavelength and 182.2mm as the guide wavelength. To excite I would place the 30.5mm long stub antenna (1/4 wavelength of the external frequency) at a right angle to the side wall length axis and 45.6mm away from an end plate (1/4 of the guide wavelength).

Is there a better way?
OK first with BD and SD equal to 200mm the wavelength iside the waveguide is: 2*91,906mm=183,812mm(lambda) at 2,45 GHz
not 182.2mm (no problem with that difference).

There are some possibilities:
1) use a bended stub antenna in direction of the E field (goes around the center)
2) use a waveguide coupling like tajmar
3) use a set of dipoles near one of the end plates
4) or a loop like in the NASA cone
5) waveguide slot/iris in the endplate (works like a single dipole)

All of that will work as well and i think almost better than the stub in your drawing.

Test it with a VNA. If it isn't work (only one options) i will take my hat.
« Last Edit: 08/03/2015 10:12 PM by X_RaY »

Offline TheTraveller

It is what it is.
Good grief, man. Is that the best you can come up with?
It is, after all, a Stone Tablet of data handed down by your Guru.

Or do you recommend we do science by ignoring the data that doesn't fit our preconceptions?

Does that include ignoring Shawyer's and Prof Yang's Force measurement data because you don't believe the group velocity is different at each end and therefore their data is rubbish and can't be trusted?

The rotary table data is what it is. Data is data. Looking at the time versus distance Blue curve it is clear the table was initially accelerating and then stopped accelerating when the power was removed.

BTW POSITION is DISTANCE. So the Dark Blue original plot is Distance moved (y) versus Time to do the move (x).

Just looked at how you massaged the Excel data to get those crap looking curves. Why did you do that? Did you think no one would look at your Excel spreadsheet?
I am quite tired of your aggressive, truculent tone. You come off like a teenager with an inferiority complex. Please cease and desist. It is unutterably tiresome how you flip into aggressive mode at the drop of a hat.

I already made it clear that this was very rough. I already made it clear that the filtering needs improvement. What you see as "massaging" is actually crude low-pass filtering.

Could say the same thing about your clearly incorrect theory of the group velocity not altering at each end or energy moving in a waveguide at phase velocity, so on and so on. Despite me showing you that you are wrong, you still believe that you are correct as otherwise your disbelief system of the EMDrive being real and Shawyers test data being real will start to fall apart.

Now you start again, trying to prove your theory that the rotary table never accelerated is correct and to do so you start massaging data to show no acceleration occurred.

Here is the reported test summary data. The EMDrive moved a 100kg mass a distance of 1.85m, with a max power on final velocity of 2cm/sec, after 80 sec of acceleration.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline TheTraveller

I search for good solutions for such problems for over 10 years now. I do it with a well known Prof. of W engineering. I know what i am saying, believe it or not. If you like to do so, do it and measure and dont forget to post the results. OK?! I have no problem with that, its your turn

Can you please explain what bad and good coupling are in reference to an antenna design exciting a desired mode in a waveguide or resonant cavity?

The examples I have used are from microwave tech books. Are they incorrect or are there better ways and if so why are the better ways better?
OK. Give me a specific problem. Which mode do you like to excite?

PS:These books are really helpful, also helpful is to have experience.
Theory is right most time, but to bring special solutions into practice is a different thing.

Lets start simple and excite TE01 in a 200mm diameter circular waveguide using 2.45GHz (121.9mm wavelength) as the external drive frequency.

I get 164.0mm as the cutoff wavelength and 182.2mm as the guide wavelength. To excite I would place the 30.5mm long stub antenna (1/4 wavelength of the external frequency) at a right angle to the side wall length axis and 45.6mm away from an end plate (1/4 of the guide wavelength).

Is there a better way?
OK first with BD and SD equal to 200mm the wavelength inside the waveguide is: 2*91,906mm=183,812mm(lambda) at 2,45 GHz
not 182.2mm (no problem with that difference).

There are some possibilities:
1) use a bended stub antenna in direction of the E field (goes around the center)
2) use a waveguide coupling like tajmar
3) use a set of dipoles near one of the end plates
4) a loop like in the NASA cone

All of that will work as well and i think almost better than the stub in your drawing.

Test it with a VNA. If it isn't work (only one options) i will take my hat.

Ok understand your point. Interesting. Especially the curved antenna to follow the transverse E field.

BTW what equation did you use to get the guide wavelength? Did you use c in atmo of vac?

Now how about exciting this in TE013?
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline WarpTech

  • Full Member
  • ****
  • Posts: 1229
  • Do it!
  • Vista, CA
  • Liked: 1296
  • Likes Given: 1751
TheTraveller's post that graphed Shawyer's turnable velocity ( http://forum.nasaspaceflight.com/index.php?topic=37642.msg1411849#msg1411849 ) made me curious to see how that lined up with the "power off" event in the video ( http://www.emdrive.com/fullDMtest188.mpg ). Attached are my results.

To try to be consistent with TheTraveller's data, each 'rotation tick' is half of each line-separated segment on the turntable. There will be a small amount of drift from switching between one of the little black rods rotating around to another. The point's location on the time axis will also jitter a little, since I was only recording times with second resolution.
The plot is POSITION vs. TIME.
Here's some post-processing for velocity and acceleration. It could benefit from a better filter algorithm. But you get a rough idea. It doesn't make a lot of sense, does it?

Looks about right to me. Acceleration stops when the power is turned off, the velocity "slowly" decreases from there due to friction. Since there is very little friction, it keeps moving at nearly the same speed for quite a while but the acceleration stops when it's supposed to.
Todd

Offline demofsky

  • Full Member
  • *
  • Posts: 165
  • Liked: 96
  • Likes Given: 1662
Wow!  Is everyone crabby today!!!   :o

Actually, I have been waiting for this.  It has been my personal experience that, when dealing a very complex knowledge domain, that just before anyone  "Groks" that domain they start to get really quite crabby.  It is like a rite of passage it seems - growth pains!  :)

Edit: Clarification.

« Last Edit: 08/03/2015 09:26 PM by demofsky »

Tags: