As I wrote at the NSF EM Drive forum, the ammonia molecule readily undergoes nitrogen inversion at room temperature. The resonance frequency is 23.79 GHz, corresponding to microwave radiation of a wavelength of 1.260 cm. The absorption at this frequency was the first microwave spectrum to be observed.  

Ammonia has been used for Masers at 24 GHz for these reasons: to enhance the power of the signal, since ammonia emits at 24 GHz.

If using ammonia, please follow safety procedures:

Inhalation: Ammonia is irritating and corrosive. Exposure to high concentrations of ammonia in air causes immediate burning of the nose, throat and respiratory tract. This can cause bronchiolar and alveolar edema, and airway destruction resulting in respiratory distress or failure. Inhalation of lower concentrations can cause coughing, and nose and throat irritation. Ammonia's odor provides adequate early warning of its presence, but ammonia also causes olfactory fatigue or adaptation, reducing awareness of one's prolonged exposure at low concentrations.
Children exposed to the same concentrations of ammonia vapor as adults may receive a larger dose because they have greater lung surface area-to-body weight ratios and increased minute volumes-to-weight ratios. In addition, they may be exposed to higher concentrations than adults in the same location because of their shorter height and the higher concentrations of ammonia vapor initially found near the ground.
Skin or eye contact: Exposure to low concentrations of ammonia in air or solution may produce rapid skin or eye irritation. Higher concentrations of ammonia may cause severe injury and burns. Contact with concentrated ammonia solutions such as industrial cleaners may cause corrosive injury including skin burns, permanent eye damage or blindness. The full extent of eye injury may not be apparent for up to a week after the exposure. Contact with liquefied ammonia can also cause frostbite injury.
Ingestion: Exposure to high concentrations of ammonia from swallowing ammonia solution results in corrosive damage to the mouth, throat and stomach. Ingestion of ammonia does not normally result in systemic poisoning.

This may or may not be related to the unknown
physics at work or it may amount to a simpler demonstration of the force involved…   http://gizmodo.com/sunlight-and-graphene-could-one-day-power-a-spaceship-1707535183

I love that you are calling it Baby EmDrive now  :)

Turns out there is a wiki about the EM drive which I just found and think is very useful as a starting point for newly interested people:

http://emdrive.echothis.com/Main_Page

it also contains a link with a very nice derivation of the resonant frequency of a conical cavity as used in these experiments, useful to determine the optimal dimensions of the frustum:

http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html

beware though that the author of the page behind this last link is very skeptical. I still think that the equations on that page are very useful to determine optimal frequency given certain dimensions of the frustum or vice versa.

Boffins at NSF say fill her up with ammonia gas at 23.79 GHz for double happiness super powers.

Thanx. Do you have a link to that reference?

http://forum.nasaspaceflight.com/index.php?topic=37642.msg1379763#msg1379763

Someone further down timidly wondered if this could be tested on your little guy.

Been reading up on this for the past few days, did hear about it in the past but used to be on the 'that cant be right'-bandwagon, things are looking better and better though, and i gotta say i'm impressed that people are trying to create EM drives at home (though i agree that the 'iulian207' youtuber should shield his prototype, this is his blog btw) and actually succeeding at it, even if on small scale.

I found these videos of a presentation by Roger Shawyer from a few months ago, where he talks about a second generation (and also some quite far out idea's, but still decent videos)

Why using powers of a few watts only? More exactly: are you carefully going steps by steps, starting with a few watts, before planning to brute-force the EmDrive with say, 100 kilowatts? If so, when? 

With just a few watts, you will measure at best very week thrust signatures, in micronewtons, like Eagleworks, that can be measured only with a very sensitive balance. What would be the point of such an experiment if it's not intended to be ran in a vacuum? The next step, with a 1kW or 2kW magnetron: the same level of thrust will be achieved with a poorly designed cavity. Or perhaps you will be lucky to reach hundreds of millinewtons with a clever designed cavity (frustum machined and polished, high Q with highly reflective gold-plated convex and concave end plates, right design factor, matched adaptative resonance tuning…) and doing so, maybe surpass Shawyer's and the Chinese publicly known devices. This may be felt touching the frustum with the palm of your hand. But again, the measure will be shown by a balance. 

For those thrust levels, people will pertinently keep ranting about spurious causes like experimental errors, EM interactions, ambient air currents, hot air jets, buoyancy and whatnot. And they will keep asking for an expensive CubeSat experiment. They will be right.

So why not trying tens or even hundreds of kilowatts with TWTs or klystrons that are readily available on the market? With 2-3 GHz microwave frequencies at cavity sizes comparable to Shawyer's flight thruster test article. You could also try the 10 to 30 GHz range. This is a little trickier because we still don't know the effect, positive or negative, of higher frequencies on thrust. But at those higher frequencies, the cavity is smaller and lighter so you can stack several of them and let them work together.

Injecting 10-100kW into the frustum, it would get very hot, very fast. This is NOT a problem: just cool it with liquid nitrogen (way cheaper than liquid helium). I'm not saying we need to build a superconducting EmDrive (not yet). Just use a copper or aluminum frustum, and cool it with liquid nitrogen. You don't even need to let it run for minutes. Just a few seconds or tens of seconds will be enough for the generator frequency to lock to the resonant frequency of the thruster, following the initial warm up period. And If your EmDrive jumps and hits the ceiling, It would be interesting to check who, among the jaw-dropped crowd, will raise to claim such a catapult thrust is due to hot air circulating currents.

Ok, we´ll do all these things - next weekend after work ;-)

Seriously - thanx for the ideas. We´ll perform several different experiments. Some of them may be not as convincing but can be achieved very fast, so even if they fail it won´t be wasted time. We can increase the power if the experiment fails. Others require more planning and time. But as we are not an institution with deadlines we just have fun trying it.

Anyone remember bob lazar and his element 117 waveguide gravity thruster...

http://www.gravitywarpdrive.com/Gravity_Generator.htm

Oh yeah, I remember that weirdo.  Dude was unhinged, but it was entertaining.  That said, this has some merit, and it might actually be a real thing. 

Will you guys create a tutorial....PLEASE!!!  If you do, it may be what helps nudge the governments of the world to pay attention.  When the EMDrive takes on mass appeal, gears will turn.

This was just on reddit:

https://www.youtube.com/watch?v=Rbf7735o3hQ

Wow, nice!
Someone commented that this might be an effect caused by the air inside heating up making the cavity lighter by the hot air balloon effect.
The builder said he will try the device upside down soon.
I am excited if he really got thrust. It´s fantastic if this device really works.

Please shield yourself a bit better than that guy :P

Yep. A grounded faraday cage around it should be ok.

Turns out its not all about the hot air balloon effect after all! I'm excited.  He posted the results.  Hopefully your team just as well if not better.

Here is some data found on thread 2 over at http://nasaspaceflight.com.

http://forum.nasaspaceflight.com/index.php?topic=36313.msg1374359#msg1374359

That´s a great sheet. Will be very helpful for the big thruster.
I´ll double check it with the reverse engineered values from several pictures.

I would love to try and help you with this experiment, as I recently disassembled my microwave oven.  But alas, I have no "cone".  Could this work without the cone?

Watch... it'll just so happen some common plumbing part has the optimal cone shape for this...  http://www.homedepot.com/p/Unbranded-Everbilt-Water-Heater-Vent-Hood-EB40665/204834530

Thanx for the hint. The cone has to be calculated according to the feed frequency, else it won´t work. We will machine cones for 2.45 GHz and for 25 GHz

I'm curious as to how it scales.  Do the relative dimesions scale with frequency (the cone slope change), or is there an optimal shape that just scales up and down in size?  If the cone is close enough, maybe you can tune the RF to match the cone.  (I don't know if you can 'tune' a magnetron like other RF generators)

It should scale linearly, because - according to the paper - the cavity is a deformed resonator. They give a formula to calculate the quality factor. Anyway they propose to alter the diameters and height and the wave injector values within some range to tune the optimum resonant frequency.

(The asymmetrical structure alters the resonance frequency, so they propose to alter the height of the cone for cmpensation)

A good frequency tuning would be a nice feature, but many affordable rf sources don´t have that feature.

Could you maybe write this quality factor formula you mention and this diameter and height tuning procedure in the project log? Or perhaps a ref to the paper?

It´s here: http://www.emdrive.com/NWPU2010translation.pdf

It´s a deformed waveguide, so it scales linearly according to the wavelength.
But there are for sure many factors depending on material, wall angle and the whole geometry.
I think there is no existing optimal formula yet. You can compare it to the first experiments with aviation. It took a long time from first experiments with functional wings to advanced simulation models. That´s the exciting part about it. It´s something new do discover :)

During the first two weeks of April of this year,  NASA Eagleworks may have finally obtained conclusive results.  This time they used a short, cylindrical, aluminum resonant cavity excited at a natural frequency of 1.48 GHz with an input power of 30 Watts.  (in the NASA article.)  So you may be able to use a different style/easier to machine cavity.

Much better link:

http://swdllc.paresspacewarpresearch.org/Construction/ConstructionAndEngine.htm

When big breaks in science and technology occur,
there are many examples of simultaneous discoveries. For example, calculus was
independently invented by Newton and Leibniz, evolution recognized by Darwin
and Wallace. While looking more deeply into the Eagleworks story, I noticed
some material I had overlooked about some physics professor in Omaha making the
same sort of warp bubble phenomena producing FTL measurements in a laser beam
fired into his device. Could the two different types of devices have something
in common (asymmetric EM fields)?  http://www.geeksnack.com/2015/03/10/functional-warp-drive-apparently-bending-space-time-omaha-garage/

CHEMONUCLEAR  FUSION CAN POWER  EM Drive spaceships.

Chemonuclear Fusion is a type of low energy nuclear fusion that has
been shown to produce energy in two experiments. Aneutronic nuclear
fusion can provide unlimited electric power without polluting the
environment with radioactive waste and greenhouse emissions.
Chemonuclear processes in small dense white dwarf stars accelerate
the rate of nuclear fusion and cause them to explode in spectacular
supernova explosions.

The Chemonuclear Fusion Project is soliciting
volunteers to help our crowdfunding and educational campaigns. Our
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This sound pretty esoterical - but on the other hand, the EMdrive was also considered as esoterical. I wish that it works.

The Shawyer stuff I read doesn't talk about quantum plasma. Its somebody else's  theory. 

I have'nt seen anything credible about  bubbles in space time. Nothing deep in the published. literature.

Good luck.. Looking forward to taking the engine out of the spare car and making it vacuum proof :-)

You really should do a kickstarter for this, a lot of people out there would chip in...

Ok. I´ll choose a microwave where I won´t need to open the casing.
I´ll use a waveguide to pick up the RF from the internal waveguide in the cook chamber.

Th eagleworks announced it will publish results of their ;latest tests in two months in July.

Great. Excited to see them.

Roger Shawyer now says that there is limit to the speed that his EM thruster can develop before it starts eating up huge amounts of energy and its efficiency goes way lower. It has to do with special relativistic dynamics . Can somebody tell me if this is correct?

 My understanding is that at higher speeds the reference frame of the back resonator wall is catching up with the slower group velocity microwaves and nullifying the effect of differential group velocities. So less electromagnetic pressure is being exerted on the front wall of the resonator.  Is that going on at  subrelativistic speeds?

I don´t exactly know the theory. Maybe the density of the vacuum virtual plasma is changing with increasing speed.