Experiment replication to observe the thrust in EmDrive device.

The device uses a magnetron to produce microwaves which are directed into a metallic, fully enclosed conically tapered high Q resonant cavity with a greater area at one end of the device, and a dielectric resonator in front of the narrower end. The inventor claims that the device generates a directional thrust toward the narrow end of the tapered cavity. The device (engine) requires an electrical power source to produce its reflecting internal microwaves but does not have any moving parts or require any reaction mass as fuel. If proven to work as claimed, this technology could be used to propel vehicles intended for all forms of travel including ground travel, marine travel, sub-marine travel, airflight and spaceflight. EmDrive is a device invented by Roger Shawyer in 1999 and replicate with success by a team from China led by Yang Juan and a team from Nasa this year. The device was also tested in vacuum with the thrust is sill present so the air convection or other possible air movement is ruled out.

I will replicate the experiment and try to observe the thrust.

Materials for the drive.

  • Cooper sheet 0.3mm (initialy intended 0.6mm)
  • transformer from a microwave oven (power ~ 800-1200W)
  • Magnetron from microwave oven: Anode cathode voltage ~ 4kV , and 3-4V @13A for the filament. Frequency 2,45Ghz.
  • solder, 4mm screws, pcb

Test equipment: Current measurement, voltage measurement, temperature measurement, micro-gram scale.




Frustrum 3D modeling in Autocad Inventor

emdrive homemade2

Connection diagram for the magnetron. Warning: charged capacitors can kill very easy. Always discharge the capacitor by putting 100kOhm resistor on the ends and also to the external case for your safety. After discharge put the ends in short circuit and wait for a couple of seconds to be absolute sure that there is no voltage.

emdriveAlmost all the materials arrived today:


Emdrive building

emdrive (4)emdrive (22)Today i will make the frustum to see the results.

emdrive (3) WP_20150513_00_22_34_ProToday after work, i will finish the setup and i will connect the frustum to a plate and suspend in the air from  4 nylon wires.

 After i power on  the temperature of the magnetron increased to 60 degree celsius.(140F) in around 5-6 seconds. If the magnetron does not have any load the temperature should rapidly increase i think, even though the microwave oven will not burn (overheat) if left on without any food inside.

In this paper : http://www.emdrive.com/IAC-08-C4-4-7.pdf they say that the thrust comes after 20 seconds you power the magnetron. But in 20 seconds the magnetron will be very hot without proper cooling ( or maybe because the magnetron has no load)

I still do not know if the waveguide in a microwave oven plays other role than just feed the microwave in to the cavity.

Another think i want to test is to try to reduce the current on the filament with a separate power supply in hope that i will decrease the power in  “search”of some thrust.

In a few days i will receive 2 plates of  PCB singe-sided, and i will try them instead of cooper ends.


Today i did the first test with the setup suspended in a pendulum. The power was applied  for 40 seconds. No thrust resulted :(

i will post the video soon.

Tomorrow i will move the magnetron above the middle of the frustum, to the small end. After power on for 40 sec temperature was 85 degree Celsius.

Next step will be adjusting the current of the filament and maybe the frequency by adding 2 separate coils over the magnets with adjustable current, to try to change the oscillating  frequency.



emdrive 008


Test No. 2

Modifications: magnetron moved to the smaller side

Coil added to the magnetron to try to adjust the frequency.

Still no visible thrust in the pendulum

WP_20150514_22_34_09_Pro WP_20150514_23_19_48_Pro WP_20150515_01_41_24_Pro



Test No 3, Thrust observed.

As you notice in the movie the weight of the foam on the frustum is 10.2gr and real weight is 3.58gr so the lever ratio is 1:2.894 in this way the real thrust was 0.508gr.

New tests will be done with the coil to see any change in thrust.

I will modify again the frustum and add adjustable length so resonance adjustment.

Emdrive test


I did not have time time to do any new setup.  Frequency counter has arrived, and i measured 2463Mhz.  . By changing the current in the coil around the magnet i will change the magnetic field created, overimpose to that of the magnet. With this change in magnetic field, the frequency output should change. I hope i can change enough to find the resonance frequency of the frustum and hope for higher thrust. The other method of finding the resonance is to adjust the length of the cavity. This can be done with a movable  plate and a screw . I can make that out of PCB.

frequency counter

frequency counter01




Hi, guys, i`m still alive . Sorry if i did not post anything this days. I noticed some guys think i died , relay strange. I do not have a Tweeter account by the way.

I flipped the cone in the original setup and i have the thrust downwards (scale goes positive). Unfortunately the thrust downwards is around 7 times smaller. difference on the scale is only 0.20 grams and is consistent with the power on and off .

Temperature discussion: during the tests the temperature of the frustum does not change to much maybe 1-2 degree.

The biggest change in the temperature is on thee fins of the magnetron. Can be as high as 80 degree Celsius. Definitely the air is going upward from the fins. (What is this meaning the the change in weight?)  The tests  shows that after power off the frustum weight is continue to decrease. up to – 0.30 grams at least. How we can explain this ?

Spring discussion:

Andy P. said something interesting : “When comparing the different thrusts, you will also have to take into account that in test 3.1 the thruster has to fight against the upward force of the spring onto which it is attached. This will lower the observed weight change on the scale, but does not necessarily mean the thrust is lower.”


This fight “against the spring” is real or not ? Lets assume this: you put 1kg on a scale and push TARE button. When you remove the weight it should not indicate -1Kg if the fight against the spring was real. Inside the scale is also a “spring” to keep the weight the the test should be the same.


I`m working the modify the cone now. Test No 4 will be with new setup.

Because i do not have a cooler to the magnetron i can not put a servomotor to continuously adjust the cavity length because  magnetron will heat fast. So i will need to manually adjust the length for each test to  observe the scale and then let the magnetron to cool ant test again.


First i will adjust in bigger steps 1cm smaller for each test.  then i will see witch one has the most thrust. After i will go around that value from mm to mm with the screw.

I do not own the picture with the adjustable setup. is from NasaSpaceflight forum.

emdrive 1b

Emdrive 4

emdrive 11

Emdrive 4

emdrive 10



emdrive 12


Unfortunately i can not continue tests for the moment because i moved from original location (another country) and i left the frustum, magnetrons, transformer, there. I was not able to carry all my stuff.

I will continue tests, but i do not know when. :(

  1. Anonymous says:

    What did you base the dimensions of the frustum cavity on?
    Very interesting, I’ll be sure to follow your progress.

  2. Blaine says:

    You having troubles? Very anxious for your results.

    • Blaine says:

      quoting from Todd D. over at nasaspaceflight.com

      From the thermal and A/m plots from EW, most of the resonance is happening at the big end. I would not put the magnetron in that space because the input there will probably perturb the waves. Shawyer put the input near the small end. I would put it “at” the small end, depending on wave polarization. The walls should do most of the reflecting, not the small end.

      Todd D.

      • Anonymous says:

        This is incorrect. Please refer to the thread you quoted that from. Shawyer had the input at the big end of at least 1 of the test articles.

        • Anonymous says:

          Actually, not incorrect, just not an assumption that was made by Shawyer. Eager to hear about the results of this attempt at replication 😀

  3. Steve says:

    Is the frustum dimension half the size of input frequency of magnetron?

  4. Anonymous says:

    Exciting to see the cavity being assembled as you showed in your newest pictures.

  5. Andre says:

    Hi, this is intriguing.
    I was hoping to build a mini EmDrive using modified intruder alarm (22 GHz) modules as these can be tuned by simply adjusting the voltage and physical dimensions of the Gunn diodes resonant cavity.

    • Andrew says:

      Problem is that you only get about 200 mW from one of those.
      That magnetron is pumping out between 700 W and 1.2 kW.

  6. Anonymous says:

    A recent message from Roger Shawyer to one of the NSF forum members: “… I feel I must emphasise the Health and Safety aspects of experimenting with EmDrive cavities. Exposure to a microwave power of 1ooW can lead to long term eye damage. A magnetron can cause blindness and sterilisation, whilst the
    high voltages involved can kill.
    The stored energy levels in a high 0, high power cavity can equate to a few grams of high explosive. In early experiments I burnt out five magnetrons and blew a small hole in a thin walled copper cavity following an internal discharge. High power EmDrive thrusters are dangerous and should only be operated with extreme care.
    I believe NASA has a duty to publicise the health and safety aspects of EmDrive experimentation before they get sued by some unfortunate experimenter.”

    • Dr Vel says:

      Can we therefore assume if you get flattened riding your skateboard in the middle of a busy interstate you will be suing the maker of skateboards, the builder of highways as well? My generation believed in taking personal responsibility of our actions, in researching and planning out what we did. Worrying about and being responsible for our own safety which implies studying, thinking of possible repercussions and dangers to our every action. How sad it is your generation does not think the same way. Because you have this mindset you not only bring about your own doom, you bring it upon others and destroy creativity and advancement for the entire world. You assume others should pay for your failures. I am glad to be old, to have grown up and lived the bulk of my life in a world unlike the one you are creating. I have always paid my own way and paid for my own mistakes. I doubt either can be said of any who think as you do.

      • Greg Parrott says:

        The attorneys in this country have fostered the ‘let’s sue’ mentality. The U.S. has by FAR the highest percentage of attorneys per capita of any country in the world. It is something like a hundredfold as many as in Japan.
        What’s worse, the laws that they themselves created are quite self serving in providing guaranteed employment. I learned firsthand how self serving it is. I worked at a company where all employees had to sign a 1 year non compete agreement to prevent employees from jumping to a competitor.
        Even though the attorneys signed it, the non compete is unenforceable against attorneys because of a legal precedent which essentially concludes that companies/people cannot be restricted from obtaining what they feel is the best legal counsel. As long as the attorney supposedly does not breach the confidence associated with their prior employment, the right of the company to obtain their choice of legal representation takes precedence over a non compete agreement, regardless of the attorney having signed it. How’s THAT for self serving?
        I asked one of several attorneys who left our company only immediately begin work with a competitor why this same principle shouldn’t apply equally to other professions. Why shouldn’t a company be free to hire the engineer of their choice as long as the engineer doesn’t breach confidentiality? The attorney could offer no reason other than the legal precedent.

  7. sfrank says:

    Dr. Rodal on the NSF forum has repeatedly suggested using an wire ring design for the end plates. This would theoretically trap the microwaves but allow air to flow thereby reducing internal temperature. If you’re having trouble sustaining operation because of overheating, perhaps try that. Search for “Cullen” on the forum post for a diagram of the ring end plate design.

  8. G says:


    Unde ai laboratorul? Te-as putea ajuta sa pui la punct un sistem de protectie. Neparat trebuie sa iti protejezi testurile tale de efectul microundelor.

    Ce mecanism de tuning folosesti?

    • tetru says:

      E in China. Nu in Romania.

    • iulian207 says:

      vad ca tipul asta nu are nici o greata sa stea langa microunde,ba chiar baga mana, eu am cavitatea complet inchisa si nu imi scapa microunde:

      • G says:

        Problema mare sunt ochii. Umorile ochiului prind foarte bine microundele si sunt foarte foarte sensibile la incalzire. Daca ai ghinion mare poti sa declansezi o cataracta ireversibila. Mecanismul e acelasi ca la fierberea albusului de ou.

        De asemena tesutul nervos poate fi afectat ireversibil prin expunere de doar cateva secunde. Din pacate simptomele apar la foarte mult timp de la expunere si sunt oribile.

        Iti recomand sa citesti toata aceasta pagina de wiki: http://en.wikipedia.org/wiki/Microwave_burn

        Sunt deacord ca tu ai cavitatea inchisa dar se poate intampla sa ai o defectiune care sa te expuna fie prin compromiterea cavitatii, fie prin scurgeri de la magnetron. Cel mai sigur iti faci o cusca faraday care sa te protejeze de experiment.

        • Owner Iulian says:

          Merci, prima chestie pe care am facut-o inainte sa ma apuc am citit despre problemele cauzade de expunerea la microunde.

  9. Anonymous says:

    Exciting to see whether the micro-gram scale will measure any thrust! Have you considered a teeter-totter setup where the setup allows you to see any reduction in the load resting on the micro-gram scale?

    • Owner Iulian says:

      I will try also this method

      • Anonymous says:

        Great job so far! You might want to try using a lever which will magnify the force/thrust to possibly be readable by a micro-gram scale.

        | Hanging |
        | EMdrive |–>|
        | lever
        —|— pivot
        | Scale |<—|

      • flux_capacitor says:

        Hi Iulian,

        Good job man! As explained on the NasaSpaceFlight forum and others here, your setup uses a spring that has a different resistance when you pull on it or push on it, hence the discrepancy in measurements between upwards and downwards thrusts.

        Glad to see you’re planning on using a teeter-totter balance. With your EmDrive on one side and weights on the right for equilibrium, it should be sensitive enough to show even the thinest thrust, and you can do it easily in the two directions. Inventor Roger Shawyer has done this a long time ago, but never released any footage.

        May you record at first the movement upwards, then reverse the frustum and record and compare the thrust downwards. Repeat the same process with the cavity embedded in a closed metallic nonmagnetic Faraday box, in order to eliminate spurious forces like air currents (and if you can, put the metal box inside a nonconductive plastic box also). All this will then get a lot more attention :)

        And take care!


  10. Anonymous says:

    (hopefully fixed the diagram)

    | Hanging |
    | EMdrive |–>|
    . |
    . | lever
    . |
    . —|— pivot
    . | Scale |<—|

  11. Anonymous says:

    I guess it deletes all the empty spaces.

    | Hanging |
    | EMdrive |–>|
    ……………….| lever
    ……………… |
    …………… —|— pivot
    ..| Scale |<—|

  12. iulian207 says:

    i already bought a scale but until i do not see any movement is useless.

  13. Moleculor says:

    What’s the sensitivity of your thrust measurement system? How heavy is the entire apparatus that is being pushed? I had the understanding that the amount of thrust being generated was so small that *visible* motion was practically out of the question, due to friction (if the object is on a surface) or gravity (in a pendulum situation).

  14. Mike W. says:

    It doesn’t look like you’re monitoring the chamber for resonance. I would add a very short probe a quarter guide wavelength from the opposite end your feeding power in and at 90 degrees from your feed probe. The probe shouldn’t be very long, 3/16″ because of the high power level and because you don’t want to lower the Q of the chamber. Find a suitable diode that will work at 2.5 GHz and monitor the DC Voltage with a high impedance Voltmeter. Watch for a sharp peak in voltage at resonance. You also need a way to tune the cavity. pull the cover off the small end and add about three inches of 3.5 to 4 inch diameter pipe. Cut a round disk and build a screw mechanism to move the disk forward and back. use 10 or more strips of shim stock to ground the disk to the inside of the pipe as it’s moved. If you can get your hands on a spectrum analyzer to pre-tune the chamber it would make things easier. Turn the power down on the magnetron so you can leave it on longer and adjust the tuning. Use the guts out of the oven you sacrificed to control the power. Increase the Q of the chamber by cleaning the oxide from the inside of the chamber. Fill it with vinegar and let it soak. Rinse it out and dry it. Last thing, it’s a lot easier to tune the chamber than trying to tune the magnetron. Hope this helps.

  15. pedraza says:

    Hi where did you get your dimensions I would also like to run some test we can possibly work together

  16. David says:

    EmDrive Test No.03 Success:

  17. Anonymous says:

    Coungratulations with the thrust! It’s incredible!

  18. tchernik says:

    Congratulations for this amazing result!

    One suggestion: turn the device upside down and re-run the test (and take video of course). If you see thrust in the other direction, you would calm down most objections related to hot air buoyancy.

    • Timothy says:

      No need. Hot air buoyancy would cause thrust in an upward direction. Notice when he turns the device on, the scale reads negative. That’s because it’s pushing down, not up. The device moves toward the direction of the big end.

      • sfrank says:

        Actually no, this was movement upwards. The scale went negative indicating a lesser load on the scale. Like Shawyer’s demonstration unit, this emdrive moves towards the small end. So Iulian could easily reverse this test to help show the same effect with the emdrive pointed down.

        But another counter argument to hot air buoyancy is that the effect cuts off pretty much instantaneously when power is switched off. Hot air wouldn’t cool that fast.

        • Timothy says:

          No, the EM drive is being measured on a lever. If the side with the EM drive goes down, the end on the gram scale goes up. In this video, the EM drive is moving toward the big end.

  19. […] Un investigador independiente fabrica su propio EmDrive y obtiene empuje […]

  20. ehem says:

    Great job !!! I suggest in future tests put all the device in glass box to cat suggestions about hot air or something.

  21. Johnny Karamazov says:

    Can’t wait for the next test, you’re doing sterling work here Sir. Without knowing where the alleged thrust is coming from, its imprudent to get too excited, but the mystery in itself is exciting enough for the time being. Keep up the good work and stay safe!

  22. Jim says:

    Can you reverse the thrust as well by flipping Em drive or polarity of the magnetron?

  23. Mike W. says:

    Your 3rd test showed the same 2-3 second delay on start-up as that shown on the NASA blog graph along with the slow drop-off in thrust over the next few seconds. Your results are the same as that already shown, good job! The slow start-up is due to the time for the magnetron filament to heat up, 2-3 seconds. The drop-off in thrust is most likely due to the expansion of your cavity as it warms up and the resonant frequency changing as it expands. It would be interesting to monitor the temperature of the cavity as you run your experiment. The coefficient of expansion for copper is about 10, not quite as high as aluminum. It looks like you used pretty thin copper which would heat up fast. You might try soldering fins along the long sides to see if the temperature curve shallows up. I know copper is expensive. Temperature guns aren’t too expensive at the hardware store.

  24. richard says:

    I hate to say it but what it looks like to me is that you have built a metal hot air balloon, Please turn it upside down and demonstrate downward thrust so that i can get excited.

    • Don says:

      Richard’s ‘metal hot air balloon’ seems like a valid question, is the chamber air tight? If so, by my quick math you should be seeing a buoyancy force of (approx) 25 milli-Newtons for a volume that size with air heated to 85C.

  25. dave says:

    Have you flipped it yet?

  26. Andrew says:

    A 25C temperature rise of the 9 litres air volume you have is sufficient to produce the -0.5 gm weight change you observed.
    So obviously you need to flip the device upside down and check again.

    17 hours ago you said you’d do that “in 2 hours”. Can we assume the worst? – i.e. that you still see -0.5 gm and so you’re measuring the weight of hot air?

  27. Malcolm says:

    Whilst it looks like your measured ‘trust’ may well be caused by hot air, don’t be put off if inverting the cone still result in an upward force. It seems strange to me that the force appears almost immediately the magnetron activates and disappears rapidly as well. I would have expected a hot air effect to drop off quite slowly.
    I’m wondering if the effect is similar to that of the spinning superconducting disk experiments performed by Podkletnov and is actually connected to gravity.
    The trust measurements of the EMDrive have I believe all been done horizontally and could be the result of an asymmetrical body that is somehow moderating gravity. The effect measured by NASA is incredibly small and I doubt your pendulum setup would result in a visual conformation.
    Perhaps go back to your horizontal experiment with it just touch (resting) against your electronic scales mounted vertically.
    Good luck, a very worthwhile endeavour.

  28. Mike W. says:

    Don’t let the hot air comments detour you. Your results match those of the other tests deemed successful.

    The best way to increase the thrust is to increase the Q of your resonant cavity and drilling holes in it isn’t going to do that. The inside should be clean and smooth, free of dents and dings. If there is any solder flux that leaked inside while you were soldering it together, you should clean it up with flux solvent. The inside surface needs to be as conductive as you can get it. Oxide can be removed with vinegar then distilled water and dried. Use microwave finger stock on your tuning plate if you can get it, will increase the Q. You’re doing a fine job, keep moving forward.

    • Blaine says:

      Wow, someone who is thinking positively about all this. I also conquer with what you said Mike W. I think he needs to put the thing upside down and run the same tests as test 03 and a lot more people will be satisfied.

  29. Anonymous says:

    I fear that the inverted frustum test has been performed, and that the measured force is still -0.5.

    • pedraza says:

      As do I but I am confident that he will reveal results and if he does find error he reseal the subject and does retest with tougher constraints to keep credibility

    • Coltrane says:

      Or he has another job and is doing these tests when he has the time.

      • pedraza says:

        I was actually thinking the same or he’s making it suspenseful so we keep coming to his site I’m on here like 8 times a day checking up on it

  30. Andy P. says:

    To exclude hot air from being the reason for the thrust, could you try a ‘dry’ experiment in which you somehow heat the cavity to a specific temperature without activating the magnetron? It we would be living in the stone age, I would suggest an open fire, but we don’t, so there should be other options available! :)

    I am very excited and looking forward to further tests! Godspeed!

  31. PM_ME_BOOBIES says:

    I think that it’s been a failure too. I was so excited for the whole thing as well.

  32. PM_ME_BOOBIES says:

    It was what, 2 days ago he said he’d do it after work. Even if it is a failure, we may be able to help tell why, and it will help our understanding none the less.

    • helix005 says:

      I don’t think failure would be the correct word actually. Just no measured thrust. NASA have only been dealing with tiny amounts of thrust that would be far to small for Iulianls set up.

      • Johnny Karamazov says:

        Now that I’ve had time to reflect I’ve come to the realisation that this whole thing, whilst interesting, is ultimately meaningless. If he gets thrust with this set up, nobody in the scientific community would bat an eyelid. It’s just a fun little experiment that a bunch of people who should probably know better are getting overly excited about for little reason. You hit the nail on the head with your comment. But hey, it’s not this dude’s fault if a bunch of excited nerds (I include myself in that) get all excited at his home experimentation. More power to him, but lets not kid ourselves that this matters or proves anything either way.

        • pedraza says:

          Lmao I have liquid heluim if it works I replicate so it is a big deal for my own financial reason you think us school girls I’m sure there is more to most of our psyches then simple excitement.

          • Johnny Karamazov says:

            His set up is so ad-hoc and flawed that nobody will take it at all seriously, except people who disregard scientific rigour and decide to get excited that a very badly controlled experiment has produced meaningless results. Nobody will be able to reproduce his results in a controlled situation because nobody would be stupid enough to waste their time balancing their ‘EmDrive’ on a bookshelf with a homemade lever, whilst heating the internal cavity up to 85 Degrees Celsius and dancing with excitement when it produces exactly the kind of force you would expect from the volume of the cavity being heated in just such a manner.

            You want to believe, so you’ve left your brains at home. Any actual discoveries will come from NASA or the Chinese, this guy has just totalled a microwave for his own amusement, nothing more.

        • Timothy says:

          I strongly disagree. Reproducibility of results is one of the main principles of the scientific method. If an experiment is reproduced, and the scientist gets very different results, then determining the reason for the difference might lead to an important discovery.

          Even if the results are the same, how the EM drive actually produces thrust is unknown. Not many people have built one yet, or done many experiments using different variables. Not only has Iulin put himself in a position to do tests nobody has every tried before, he has also put himself in a position where he could make an accidental discovery at any moment. All it takes is for something unexpected to occur, or perhaps and observation that others might have missed, and then, a eureka moment!

          There’s no telling what may come of this. He may have an entirely serendipitous moment and randomly discover how high temperature super conductors work, which is another device that works with no known explanation. Anything can happen when you’re exploring the boundaries of what is known.

  33. Jim says:

    Shawyer and NASA measured thrust horizontally. Can hot air explain that?

    • Andrew says:

      Of course not. A vertical thrust measurement includes the weight difference between hot and cold air in the volume. A horizontal thrust measurement does not see this.

      • Anonymous says:

        Since thrust reaches a stable plateau after magnetron is turned on it might be real since hot air would contiuing heating up

        • Andrew says:

          Astute observation. It’s been suggested to me that sparking and arcing inside the cavity is a dominant mechanism for heating the air/water vapour. I believe the crackling can be heard on the video, but it isn’t on all the time. I surmise that’s because there’s a drop in density, and/or that the humidity has reached a minimum when all the water vapour is flash steamed and driven out.

        • pedraza says:

          The thrust begins to decrease this would be due to the heating of the cavity which decreases the q but it could be hot air escaping.

          • Anonymous says:

            I think this passing trough a maximum might be due to the magnetron frequency passing through the resonanzpoint of the cavity due to changing temperatures

  34. Rebecca says:

    Have you measured rf/em frequencies/activity outside cone/device top, bottom, sides, etc. during power up/down?

  35. Hi, Iulian!
    Please, post smth just to let us know that you are fine and that you didn’t get hurt during the tests.
    I think, a lot of people are a bit worried about you.
    Thanks a lot!

    • Natalie says:

      I agree, I’m starting to get worried that it exploded or something.

    • David says:

      I agree, just write, “Hi, i’m alive and busy”

      • pedraza says:

        You guys sound so needy. I’m not trying to be mean but let him do his work.( although I probably makes him feel good that we all keep commenting ) now here’s what we will do if he dies he will message

  36. Adam says:

    Two grams upwards thrust of a cavity at 85 C would be expected. More than that would not be. And two grams downwards really wouldn’t be.

  37. Jim says:

    I don’t quite understand how the negative weight reading could be from hot air. I thought the reason heated air rises is because it expands and is therefore less dense than the surrounding air. But the air in the copper cavity cannot expand…can it? And if it can’t expand, how can it become less dense than the outside air and rise?

    • Natalie says:

      There are a couple of holes in the device through which the hot air could escape, making the density of the air inside the cavity reduce.

    • Andrew says:

      The cavity is not sealed. It has a volume of about 9 litres. Therefore when the air inside it (and its associated water vapour) is heated, it can escape so as to assume the lower density it must have at the same pressure. Therefore that 9 litres of air now weighs less when the air is heated.

  38. jacob says:

    omg has he died? where is he? anyone checked romania news for death by microwave? i so sad he might be dead. he was a visionary.

  39. rg says:

    The simple “hot air” test is to provide a calibration with ‘hot air’ perhaps simply place a light bulb just below the cone and turn it on and off to see the effect of hot air producing the effect. Do this alternating with the microwave power. Add some light bulb heat to the microwave power. Ideally take the temperature of the air inside the cone while testing with the light bulb heater. What about building a simple microwave Faraday cage around the whole apparatus for safety sake.

    • Andrew says:

      The most direct way to decouple a vertical thrust measurement from changes in air mass due to heating, is to enclose the device in something sealed. A plastic bag will do, provided new phantom thrusts are not generated by:
      1. A changing footprint on the floor; so keep it held up above the floor.
      2. Bag thickness not too small; else it will tend to balloon and create buoyancy.
      3. Not prefilled with air, else again buoyancy as it fills with hotter air; so prefill.

  40. lurker says:

    Please inform us if you are ok, the dangers of suffering burns or beryllium poisoning have us all worried.

    • Michael says:

      I posted a message to a person on his Facebook with the same last name as Iulian saying people are beginning to get concerned. Hopefully they can pass a message to him.

      • Anonymous says:

        Hi ,
        Assuming that the demonstration power on/offs in the video where done in close succsesion: the zero readings drifted from 0.02 in the first run to average 0.11 in the following. Could that be the hot air lift like it would be in a hot air balloon being heated with hot gas?

      • Anonymous says:

        The heating of the air inside the frustrum would be limited by the short power on phases and the heatsink effekt of the copper walls exposed to ambient temperature so one would probably expect a value way below 0.5 celsius of heat increment.

  41. Anonymous says:

    Sorry should be 0.5 gram lift increment

  42. xavier says:

    I really like this initiative, but I have the feeling that the upside-down test may have failed.
    Anyway I wish I’m wrong.

  43. Anonymous says:

    I just read in shawyers emdrive home page how they measured acceleration.
    Looks quite tricky .he says this vertical suspended method willnot work.acceleration has to be measured under dynamic condition (under acceleration?)read it .according to him the chinese did it that way as well

    • David says:

      Can you please share a direct link or add a quote from shawyers published info ?


    • pedraza says:

      i found the same information that is why testing it is such a issue I will most likely create my own and build for self confirmation as well as the need to try this in super conduction condition which should rise q by 4 powers creating a useable amount of thrust. the best metal I can come up with that is easily accessible seems to be copper because I can bring that down to 4 k to put it in super conduction conditions using helium but I am still drawing out designs as helium will suffocate you if you use it wrong and it is a super fluid so its like trying to keep ants in a jar except the ants evaporate and kill you

  44. Dear Iulian,

    Could you please update with the results of the inverted EmDrive test? Even if said test results in an upward thrust again, it does not mean failure. Together we can come up with an improved set up if you like?

    Kindest regards.


  45. Anonymous says:

    I am anxiously waiting for the results of the upside down test. Has something happened?
    Even if the result was negative, please report your findings.

  46. 1000001100000111000111110001111 says:

    If you are not going to perform any more experimentations please let us know so that we can leave you in peace. Thank you.

  47. seventeenaardvarks says:


  48. Hans says:

    Many people are worried about the results of test number 4. Please give an update, even if the thrust in test number 3 was due to air buoyancy.

    • seventeenaardvarks says:


  49. seventeenaardvarks says:


  50. seventeenaardvarks says:


  51. seventeenaardvarks says:


    • Quantum Natalie says:

      If this is true, I’m very sorry to hear this. I guess he was over confident in his ability to control the microwaves safely. R.I.P.

  52. Anonymous says:

    Chill out! He isn’t dead. Holy crap. Its like you people are on drugs.

  53. Anonymous says:

    it is ridiculous to hurt himself to die in this way

  54. dave says:

    Iulian is fine and is working on the project. He will post when he is finished.

  55. Anonymous says:

    Hi David
    Its:emdrive force measurement

  56. Stephen says:

    Hi lulian, good to see the new pictures. Was worried you disappeared in a Warp bubble for a moment! ;). Good luck with the next experiments.

  57. Blaine says:

    Ha, it wasn’t all hot air after all!

  58. Andrew says:

    We can figure out the true thrust now (T=thrust, a=air effect, in gm-wt)
    T + a = -0.54
    -T + a = +0.54/7
    solving by eliminating ‘a’ gives
    T = 0.31 gm-wt

    • Anonymous says:

      Just an idea:there will be a heat gradient inside the frustrum from bottom to top.now invertet the wide end is up and deformation of the frustrum due to heat expansion will be diffrent affecting resonance of the frustrum diffrent
      That will affect the q factor diffrent and might explain the factor of 7

  59. Stephen says:

    Did you already check out the ecat world site it’s a different technology but you might find it interesting. After reading your other projects I’m quite curious what applications and uses someone like you could come up with if you get this technology to work someday.

    • Holly says:

      Most agree the ecat is nonsense. And as the “inventor” doesn’t want people to know how it works, it’s smells like a huge scam. Something he’s done before.

      • Stephen says:

        Still my hope is its real, and that the truth is more beautiful. I still think the website I mentioned is worth a read. I like their open science approach. At least we are seeing a great experiment here with the EM drive and it is possibly showing some good results :)

  60. Hans says:

    Thank you for the update! These are very good news indeed. As the scale shows 0,2g downwards thrust (negated by air buoyancy) with the frustum inverted and 0,5g with the frustum oriented with the small end upwards (enhanced by air buoyancy), perhaps the difference between these could be used to work out the approximate thrust.


    {x+y= 5, x-y= 2}

    Reduce[{x + y == 5, x – y == 2}, {x, y}, Reals]
    {{x == 7/2, y == 3/2}}

    Thrust: =7/2=3,5g= 34.3 Millinewton in both frustum configurations.
    Buoyancy =3/2=1,5g

    MW of the magnetron?

    • Holly says:

      I do believe that Iulian meant that he was getting a downward “thrust” with AND without power to the magnetron. So, basically no movement at all.

  61. Jbarr says:

    You’re doing great work sir.

  62. David says:

    Even though there is less thrust, i find these results amazing:

    Test No 3.1 Frustum upside down position

  63. Andy P. says:

    Good news, quite intriguing!! :)

    When comparing the different thrusts, you will also have to take into account that in test 3.1 the thruster has to fight against the upward force of the spring onto which it is attached. This will lower the observed weight change on the scale, but does not necessarily mean the thrust is lower.

    • iulian207 says:

      I do not think the down force should be smaller because of “fight to the spring”. Think of this: If you have a scale and you push TARA with 1kg on the scale, when you remove the 1kg weight you shoud see -1Kg. So everything is reversible. There is already a big force in the sale to try to resist the pressure.

    • Mikhail R says:

      I agree. The whole construction is springy, so moving this bucket (i mean enginge) upward should be actually easier (requires less energy/force) then moving it down. Author shuld try to put the scales right under the engine (wthout any constructions that uses strings and flexible sticks) to measure the real thrust when upside down. Just put in on the scales, that’s all you need :)

  64. LoreChano says:

    I think it stops working in the last attempts because it have hot air inside. That’s why it stops working right. The first attempt is the better.

  65. Timothy says:

    Don’t be discouraged by the low reading. In test 3.1, I think the piece holding the bar is acting as a fulcrum, which is messing up your reading. I believe it is producing more downward thrust than your test data shows. You may need to devise a better method of measuring the thrust.

    Not only does the positive reading prove that the device is producing thrust that cannot be attributed to hot air, it also suggests that if the device is producing any upward thrust due to hot air the downward thrust of the device is strong enough to overcome it. I suspect that if you preformed this experiment in a vacuum, your thrust measurements would be higher and more accurate.

  66. Andrew says:

    Yes, the balance is far from ideal. Yes, the difference in mass between hot and cold air plays a role in what’s measured. Yes, the readings were unstable. But…the key takeaway here is that the net measured weight change flipped from up to down when the frustum was flipped upside down. That means that we need to keep paying attention.

  67. Hans says:

    Exciting to see the adjustable setup being built!

  68. Timothy says:

    The “fight against the spring” is a real thing. It’s called Hooke’s law. The upward force of the spring will be proportional to its extention. This means the more the device pulls down on the lever, the more the spring will pull it back up.

    • Lars says:

      Although Hooke’s law is real for sure, a “fight against the spring” should not change the reading on your scale. If you have a hanging scale, like what you use to weigh a suitcase (or fish if you are into that), the weight of your suitcase/fish does not change whether you attach it via a spring or directly.

      • Andy P. says:

        You’re right, it won’t change. But your problem is not applicable in this case: It is not about the weight of the scale but about the thrust that is needed to excert a force on the spring to extend it. This required force increases proportionally with the extension of the spring. Hence , the thrust required in test 3.1 to exert the same ‘apparent’ weight change as in test 2 is much higher. Since the setup didnt change (except for vertical) the thrust observed in test 3.1 is expected to be much lower.

        • Lars says:

          The situation I sketched is indeed not equal to Iulian’s setup i realize now. But since the spring is in both experiments extended to the same amount (up to were the arm is resting on the scale), the same force is on the spring in either case.
          In my opinion there is no fight agains the spring, but I agree that an experimental setup that would not give rise to such uncertainty is preferred.

  69. Timothy says:

    You could build a simple podium. It wouldn’t need to be expensive at all. First, you’d need a non-permanent adhesive (putty would be ideal because it’s also reusable), and use it to attach a structural cylinder (pvc pipe, a plastic cup, whatever you have available) to the scale. On top of this attach the sheet of copper you were using to shield your scale from microwaves. Then, put another structural cylinder on top of that. Place some feet around the base of the scale to prevent tipping. Finally, you can attach the EM Drive with your non-permanent adhesive to the top and preform your measurements.

    • Andrew says:

      You could buy a bigger scale, to eliminate the spring doubts.
      I also think that many are willful to give you small donations through Paypal, as long as you describe how you will spend them, what equipment do you need and you keep showing us your experiments (like you are doing).

  70. Curt says:

    Next thing that needs to be ruled out is any Lorentz force produced by the magnetron. Can it be mounted upside down in the chamber?
    Can you try putting compasses next the EM drive to see if the copper is getting magnetized and interacting with the earths magnetic field.

  71. Terry Newton says:

    Nice to see reversal of thrust direction when flipped! one possible reason for the difference in magnitude might be deformation of the chamber – this thing is very sensitive to resonance so even small shape changes can have a big effect. The tunable approach is wise.. might need retuning when flipped due to sagging effects. Regarding hot air… I’ve never noticed the air inside a microwave oven getting hot and the thrust disappears almost instantly when power is removed.

    Might want to try monitoring the input power using a kilowatt meter or just the amps through one of the AC input legs using a clamp-on ammeter. If anything to calculate thrust/power ratio but could be input power changes due to resonance.

  72. Jim says:

    The EmDrive has been ridiculed by other scientists because Sawyer does not take into account of the sidewalls into his calculations. They say that the microwaves also push down on the sidewalls so no net positive force in any direction is created.
    However, I think I have an idea that may improve the net force of the EmDrive. Microwaves bounce around inside the EmDrive before that energy is converted to heat. What if the sidewalls were made of a metal that converted the energy to heat more rapidly than the flat-ends? For example, the sidewalls could be made off copper and the flatends could be made of tin. Tin heats up more slowly than copper so the microwaves would bounce off the tin generating a force. When the microwaves hit the copper sidewalls some of that force is converted to heat quicker than the tin, and therefore there will less force on the sidewalls as compared to the tin.
    So, if the EmDrive is multicompound with tin ends and copper sides then a bigger force will be generated.

    • Andrew says:

      Jim – a creative idea, except that you’re using classical physics to get an answer, and the thrust resulting is predicted to never exceed that of a photon rocket. The measurements made by the Chinese and by Shawyer purport to be 1000 times higher than this, for a given power input level. So I wouldn’t get too excited about conventional optimisations.

  73. iulian207 says:

    0.5 grams multiplied by 1000 means half a kilogram. The ma thrust in Chinese experiminet was only 30 grams (this if we talk about first movie. because on the second one you need to subtract the upward force from the heat)

  74. Jim says:

    Or, to increase Q have tin side walls and silver ends.

  75. Vendicar Decarian says:

    You are not controlling for variations in buoyancy as he chamber changes shape and the air inside is heated.

    Hot air = less dense air = and upward push on he chamber.

    The balance method of detecting the thrust is lame.

    What you need to do is place the power supply and frustum in a box, free from movements of free air, and supported by a mono-filament wire

    The wire will twist if any thrust is generated, and the angle of twist will determine to a good accuracy the amount of force generated.

    Attaching a flat surface mirror onto the wire just above the support will allow you to reflect a laser pointer beam across the room and measure minute changes in the twist of the wire.

    If you intend to pass current through the supporting wire, then make sure you also include a dummy resistive load as a control, so that you can subtract away the twist that results from the heating of the support wire.

  76. TheTraveller says:

    To test the linearity of your balance system use 2 coins of equal mass.

    Put one coin on top of the centre of the frustum. Null the scale. Remove the coin and note weight reduction. Repeat 5 times and calc average.

    Next put one coin on top of the centre of the frustum. Null the scale. Add one coin on top of the 1st and note weight increase. Repeat 5 times and calc average.

    You now know how your balance system reports equal weight gain and loss. You can then use the measured factors to adjust the weight changes produced by your EM Drive in either orientation.

  77. Timothy says:

    I don’t understand why everyone is using Copper. Aluminum reflects microwaves too, and it’s also lighter and cheaper.

    • Blaine says:

      I agree Timothy. We need to use something besides copper sometime in the future. I was thinking about donating to Iulian too.

      • Timothy says:

        Cost is one thing, but weight is also an important issue if he ever wants the device to move. Copper is 2.36 times heavier than aluminum. In order to produce movement, the ratio of the force of the thrust to all other forces acting against it must be more than one. For example, if you are trying to make an object fly in a vacuum, the upward thrust to weight ratio must be greater than one. If he wants to use the device to power a bicycle, he will be fighting the forces of gravity, friction, and wind resistance. He’s nowhere near producing enough thrust to power a bicycle yet, but getting the device to move itself would be a good intermediary goal along the way.

    • Iulian(owner) says:

      Cooper ads a much better q factor to the walls.

      • Timothy says:

        Thanks for responding! I’m actually a biologist, so I’m learning quite a bit from reading your updates.

        • pedraza says:

          copper is also easier to create a super conduction conditions

          copper about 4 k
          aluminum about 1.5 k

          2.5 degree difference but hell of a cost difference

  78. Mike W. says:

    To raise the Q, the most bang for the bucks is to silver plate the inside. Probably can get it done for $50 or less. This is from an old microwave engineer.

  79. Blaine says:

    Hmmm…I feel like a little kid saying this, but I wonder if your going to post your new test sometime today Iulian. Keep up the good work and thanks.

  80. mezz dog says:

    i’m so hyped/warped

  81. Harald Schmitt says:

    First, we should evaluate if there is an interaction with the earth magnetic field.
    In this case we normally expect a force parallel to the ground.
    But maybe we have an interaction also with the electric field inside in an unkown kind.

    To evaluate this interactions, I recommend to create a large magnetic field outside of your test preparation.

    I suggest to vary the outer magnetic field and check if the results are changing.
    Please let me know your results if follow my suggestions and realize the tests.

  82. Harald Schmitt says:

    what I noticed is the delay of the effect. After you turn on, it needs a second before be effect shows.
    Does the microwave needs this time for the creation or our balance.
    If not, maybe the time is important to create the effect.

  83. Mike says:

    “what I noticed is the delay of the effect. After you turn on, it needs a second before be effect shows.”

    The magnetrons generally use a heated filament cathode, microwaves are not generated until this heats up and starts emitting electrons(thermionic emission). If you listen carefully you can hear the point where the transformer goes under load (@ 4.06 in the video) it also interferes with the video sound at this point!

  84. Frank says:

    I eagerly away test #4, this is so exciting! It’s one thing to hear bits and pieces from NASA but another to have someone who is actually communicating to those who are interested!

    Can’t wait, keep up the great work!

  85. nilabrk says:

    There was talk on NSF that adding atmosphere may increase performance. In the baby em drive’s case it was ammonia gas (resonates at the ghz freq required for the cavity). For the microwave versions it would be, of course, simple old water. It was speculated that this may have accounted for the lower effects in a vacuum (the Eagle Works drive was not a pressure vessel). Could be a bit of a hairy experiment though.

  86. Bob Sanborn says:

    I notice that everyone is using a magnetron. This has the advantage of high power but the frequency is fixed by the cavities in the device. You could use a PLL tied to a servo to change the tapered cavity’s resonence but would it not be much simpler to make the tapered cavity the frequency determining element in a very basic oscillator and/or modify the magnetron such that
    the tapered cavity becomes the direct frequency determining component for the magnetron??


  87. nick testein says:

    re Bob Sanborne; frequency is determined by the speed in which the electrons pass by the cavities not the cavities alone. The fixed magnets on a magnetron and the current driving it determine this spin and its speed. Alter magnetic field, alter frequency.

  88. Harald says:

    To check if something like a “Warpfield” is created, you are able to check it by changing the arrangement of the gauges:
    Place the scale on top of the device and measure the weight of an aluminum cone.
    Because the field may interacts also a little bit outside, then you might be able to measure a change.
    You can also use a pendulum. If it changes its orientation and/or oscillation period, then the effect is also felt outside.

  89. Jon says:

    I want to see anther video!!!!

    • b0nafide says:

      I am also eagerly awaiting the next results, whatever they may turn out to be. Iulian may be looking into a spectrum analyzer, if so perhaps the next test will not occur until his setup has been improved.

      Iulian has a head start on the other replications that are taking place. But we may get to see results from other projects this summer, it seems like the hackaday.io project is nearing it’s first test for example, and others are aiming for tests this summer. The question of whether or not the effect is real and scalable should be answered soon I think.

  90. Nicholas Crook says:

    Try rotating it while it’s operational

  91. Stephen says:

    All the best for your move and getting your stuff transported over eventually. Looking forward to seeing your tests when again when you are settled in and ready.

  92. John Newell says:

    Good Luck :-)

    Alternative theory of operation at above sight.

    John Newell

  93. Iron says:

    Good work Sir! 😉 & thanks for what your trying.

    Remember your doing it for you, not these idiots & that’s whats important m8.

    P.s God bless, hope it works! & are you recruiting crew yet? (I’m a good cook & OK with a gun).

  94. The resonant cavity you made has a lot of visible irregularities. Small irregularities (possibly even microscopic) will drastically lower the q factor.

    When is the Eagle works going to publicizes their latest experiment? I heard it might be in August. I’m looking forward to those.

  95. Joshua says:

    The magnetron frequency is determined by the physical geometry of its internal vanes which resonate. I don’t think you will have much success varying its frequency by changing its magnetic field. Anyway, keep up the excellent work! Try to get a copy of labview and some better scale instrumentation.

  96. Anonymouse Scientist says:

    I saw your “success” video. I hope you know that mass is calculated ASSUMING that the gravitational pull of the earth is constant. When you place a lever on the scale you increase the force on the scale and you end up with a multiplicative factor to the mass. If you were legitimate you would find the difference of the multiplicative factors with/without power applied. You did not do this.

    • Umm says:

      “As you notice in the movie the weight of the foam on the frustum is 10.2gr and real weight is 3.58gr so the lever ratio is 1:2.894 in this way the real thrust was 0.508gr.”

      Is this what you were looking for? He was explicit in stating that the measured force on the scale was not the same as the actual force exerted by the fustrum and calculated the ratio. It has all been discussed months ago.

      Unless I am totally missing what you are trying to stay (I really don’t think you mean to say the earth’s gravity is somehow different when the power is turned on…) :)

  97. […] There has been a tremendous upwelling of amateur scientific interest in the EmDrive. Although the microwave cavity needs to be made very precisely, and tuning microwave resonance is not simple, building one does not require great resources. As well as a lively technical discussion on NasaSpaceflight.com, there is now an EmDrive wiki, listing more than a dozen projects to replicate Shawyer’s drive. At least one experimenter, Romanian electrical engineer Berca Iulian, has posted positive results online and invited comment. […]

  98. Jimmy Johnson says:

    Your 3D Cad drawings are beautiful, your videos are well done, and your fabrication skills are impressive. What is lacking in your experiments is a better understanding of RF engineering. The equipment to be successful in what you are trying to do is very expensive, microwave network vector analyzer, high power circulators, very high power VSWR meter, spectrum analyzers, etc. There are however some available tools and practical tricks that you can use to give you a better chance of seeing meaningful results.

    First, if you are actually delivering the magnetron power to the cavity, then the cavity will heat up and the magnetron will run as cool as it does powering an oven with bowl of water. The better the match, the more heating in the cavity and the less in the magnetron.

    Second, the truncated cone resonator you are using can support a number of electromagnetic modes (resonant field patterns). If you are able to match the cavity to the magnetron, that does not mean you have excited the correct mode to produce thrust. You should be able to determine the excited mode by means of very lightly coupled probes into small holes in the cavity walls. For each mode pattern there will be places in the cavity where the field is maximum or zero.

    Third, because the cavity geometry is axisymmetric, you can use the free RF program Superfish to determine the modes in the cavity, the best place to excite each mode, and the Q of each cavity mode. Superfish will run fine on a PC. Many accelarators far more complex than what you are doing were designed using Superfish and its support programs. The program will allow you to see the fild patterns for the different cavity modes, which is helpful.

    Finally, the post that discussed the lethality and dangers of high power microwaves systems is something to pay heed. The biggest killer for the microwave system is the DC power supply. The RF parts will not likely kill you but you can get some serious sirface burns even without a very good match between the magnetron and the cavity. A rule to keep in mind is that the power circulating in the cavity is Q times the power from the magnetron when you have achieved a match. The Q of the cavity you are using should be in the thousands, say 5,000 including the joints and large holes. At match with a 1 KW magnetron the RF fields in the cavity for a cavity Q of 5000 are equal to those of a 5 MW source. The safety concerns are not to instill fear or deter your investigation, just information for you to take appropriate safety precaution.

    Good testing and good luck.

    Jimmy Johnson

  99. Guy Thomas says:

    This is just simply amazing and awesome work – well done!

  100. […] casalingo stava per essere testato in open science tre mesi fa, ma il tentativo si è subito arenato. Nel marzo 2014 "la NASA" provava il Cannae Drive inventato dall'ing. Guido Fetta e un dummy […]

  101. […] википедия (на английском языке). В мае 2015 года румынский инженер собрал EmDrive самостоятельно и провёл независимое исследование […]

  102. Borys Latysh says:

    Проверка опыта немецких физиков с помощью бытовой печки СВЧ. Украина, Днепропетровск. 31.07. 2015 https://youtu.be/CUojfkAtPds

  103. Jimmy Johnson says:

    Unfortunately I do not read Russian, but the Borys Latysh’s youtube post visual is a very good comment on the problem of electromagnetic interference. The metal cantilever makes an excellent pickup to enhance the transfer of the magnetron microwaves to the scale. A very quick and dirty estimate of the effect of EMI (electromagnetic interference) can be made by placing the scale inside of a fine screen box that is soldered closed. The screen will be visible and the scale can be turned off and one with a thin rod. There will be an effect from the spring constant of the mesh box, but that can be calibrated out.

    Jimmy Johnson

  104. Randall says:

    could you email me and let me know the cost to build one??? i’m intrested in researching this but i do not have the tools or skills to build this!

  105. Burkhard says:

    hi julian

    please repeat your Emdrive test with a encapsulated Emdrive

    hang it up on a string and watch wether the Emdrive is rotating

    try both directions

  106. rodney says:

    Why do you not use a tapered waveguide in your setup?

  107. Luiz says:

    And if use 4 magnetron converting emissions in the center of the mounting radius?
    Have you considered this?
    The adjustment of the change in frequency was a good idea. I could continue this test this idea using the magnetron 4 together.

  108. pippogsm says:

    Ce se mai aude? Ard de nerabdare :)

  109. ZeuS says:

    Just a wacky idea, if the irregularity between EM waves is generating the force. How would it respond if other than air, like another airy-medium was inside the copper container ? and/or if “it”/air was compressed ? … I’m no science major, just a imaginary response to what I can grasp from theories on EM Drive