...@frobnicat, thank you for taking the time to write up a very nice reply and you have some great ideas as well as some nasty problems. You're right on with the thinking that I could increase sensitivity by submerging the whole drive and the problems that would occur because of it. Heating as in a hot tub environment isn't going to happen, sorry that's just for me and... This was the thing we saw in ASW when we did a frustum shape cavity and submerged it with a little antenna popping out of the water. Power it on and the length on the antenna would change. Totally baffled everyone. I'm going to think some more on this and I might have an idea but let me bounce it around between my ears for a bit.And thanks again,Shell

...(*) This is also obvious in Todd's picture:where it is obvious that as θ -> Pi/2, or 2θ -> Pi, the cone angle becomes 180 degrees, the walls of the truncated cone (denoted as "tapered waveguide" in Todd's drawing) become a line, and the "truncated cone" height goes to zero, such that the truncated cone becomes the base in Todd's picture. The cylinder drawn by Todd to the right of the cone (denoted as "straight waveguide" in Todd's drawing) is a completely different structure that is not present in Zeng and Fan's discussion. Zeng and Fan only discuss the cone (there is no cylinder next to it). Keep your focus on the cone in Todd's picture and you will see the cone flatten out to a line as θ -> Pi/2, or 2θ -> Pi.

Quote from: Rodal on 06/12/2015 10:02 PM...(*) This is also obvious in Todd's picture:where it is obvious that as θ -> Pi/2, or 2θ -> Pi, the cone angle becomes 180 degrees, the walls of the truncated cone (denoted as "tapered waveguide" in Todd's drawing) become a line, and the "truncated cone" height goes to zero, such that the truncated cone becomes the base in Todd's picture. The cylinder drawn by Todd to the right of the cone (denoted as "straight waveguide" in Todd's drawing) is a completely different structure that is not present in Zeng and Fan's discussion. Zeng and Fan only discuss the cone (there is no cylinder next to it). Keep your focus on the cone in Todd's picture and you will see the cone flatten out to a line as θ -> Pi/2, or 2θ -> Pi.Jose,We are talking around each other. Thank you for going through all that. I understand what you are saying about spherical coordinates and r => infinity as theta => 0, gives a cylinder now. However, my drawing represents a traveling wave propagating down a cylindrical hollow waveguide, that is terminated by either a plate, cone, frustum or coupler. This interpretation comes from what Zeng and Fan wrote;"In recent years, hollow metallic waveguides with a conical taper have been investigated in view of their applicability as couplers."They are talking about traveling waves in a waveguide, so I drew the diagram as such... In this application, the cylinder is terminated with a conical section called an "attenuator". The half-angle theta of that section goes from a cylinder at theta=0, just as you said above, to a flat plate at theta=pi/2. At any angle in between, you can truncate the cone with another cylindrical wave guide, plate, sphere, cone or whatever, which is what I attempted to show, that the end section could be "anything".I hope we are on the same page now. The smaller the angle, the greater the phase shift of the reflected wave relative to the standing waves. If the angle is large, the phase difference between a flat-ended cylinder and a truncated cone will be negligible, where a small angle will have a large phase difference between a flat-ended cylinder and a longer truncated cone.Todd

My interpretation of kr on these diagrams is, 2pi x number of wavelengths. So these diagrams show 5, 10, 15 wavelengths. You can understand that a frustum that is 1/2 wavelength long, does not have enough length to absorb much energy, and it should be several wavelengths long I think. It makes a good resonator, but a very poor thruster.Todd

I don't mean to stick my nose into your discussions, but doesn't the half angle also go to zero when height goes to infinity?

Quote from: aero on 06/12/2015 04:01 PM...I wish someone else would do some FDTD runs so I would have someone to discuss wierd resiults with.Since I went to a bit of trouble installing it, I'll run through the tutorial and the try loading the file you posted. Hopefully I can figure it out.A question (perhaps the first of many); I assume Meep is solving Maxwell's 4 equations, two static equations (Gauss' law for E and B) and two for electrodynamics.Do the near-field/evanescent waves result from the contributions of the two static equations?Does the fine-structure constant have anything to do with the near-field/evanescent waves and Maxwell's equations?I read some paper posted here about (4-wave mixing?) and photon-photon scattering/acceleration.Obviously, I don't even understand enough to ask the right question the right way.

...I wish someone else would do some FDTD runs so I would have someone to discuss wierd resiults with.

Quote from: mwvp on 06/12/2015 07:34 PMQuote from: aero on 06/12/2015 04:01 PM...I wish someone else would do some FDTD runs so I would have someone to discuss wierd resiults with.Since I went to a bit of trouble installing it, I'll run through the tutorial and the try loading the file you posted. Hopefully I can figure it out.A question (perhaps the first of many); I assume Meep is solving Maxwell's 4 equations, two static equations (Gauss' law for E and B) and two for electrodynamics.Do the near-field/evanescent waves result from the contributions of the two static equations?Does the fine-structure constant have anything to do with the near-field/evanescent waves and Maxwell's equations?I read some paper posted here about (4-wave mixing?) and photon-photon scattering/acceleration.Obviously, I don't even understand enough to ask the right question the right way.I'm sorry, but I'm no expert on the internal operation of Meep. I've found a few background papers but not one that describes FDTD and Meep in the same context. Here is one paper that may interest you but doesn't answer your specific questions.http://web.ics.purdue.edu/~pbermel/pdf/Farjadpour09.pdfAnd if you have problems operating meep, ask and I'll try to answer .

2 Pi r /wavelength = 5

Quote from: aero on 06/12/2015 04:01 PMI'm still fooling with meep, trying to get some 3D images and yesterday I had an interesting accident with the code. Using what I thought was a sealed "Bradycone" cavity in 3D, I continued to see extensive RF energy outside the cone. Of course that can not be as we understand things. I made a Force/Power run and meep measured 10+ times ideal photon rocket.On further investigation i discovered that I had modeled the dielectric shifted in the Y direction - sideways - instead of axially. (Meep uses different coordinates in 3D that in 2D, it seems) So with the dielectric penetrating the center of one of the sidewalls of the cone (still oriented with dielectric and cavity ends parallel) F/P was 10 times higher than typical. OH, and this model won't resonate, that's where my investigation started.I don't know if the above is meaningful but I found it interesting. I wish someone else would do some FDTD runs so I would have someone to discuss wierd resiults with.I have Meep up and running on Ubuntu 15.04 and have been posting on thread 2 an image and video of a 2d simulation with a dielectric. If you point to the latest version of your model I can try to run it.

I'm still fooling with meep, trying to get some 3D images and yesterday I had an interesting accident with the code. Using what I thought was a sealed "Bradycone" cavity in 3D, I continued to see extensive RF energy outside the cone. Of course that can not be as we understand things. I made a Force/Power run and meep measured 10+ times ideal photon rocket.On further investigation i discovered that I had modeled the dielectric shifted in the Y direction - sideways - instead of axially. (Meep uses different coordinates in 3D that in 2D, it seems) So with the dielectric penetrating the center of one of the sidewalls of the cone (still oriented with dielectric and cavity ends parallel) F/P was 10 times higher than typical. OH, and this model won't resonate, that's where my investigation started.I don't know if the above is meaningful but I found it interesting. I wish someone else would do some FDTD runs so I would have someone to discuss wierd resiults with.

And if you have problems operating meep, ask and I'll try to answer .

...A) the FD scheme is extremely demanding of computer resources. It can be mainly justified for nonlinear constitutive equations, that need small time incrementation in the time domain.

...B) I haven't seen enough information yet on what one would be modelling with Meep for the EM Drive. What constitutive equations? where do we get the constitutive parameters from ? imaginary values of susceptibility? coupling coefficients? nonlinear constitutive parameters? (not available in the Internet)

...Unless you emit something to the outside: one needs to either emit mass or energy to the outside to have propulsion.

Video alert: A couple of weeks ago, NY hosted the world science festival. One of the panel discussions was about our friend, dark energy and the expanding universe. It remains a little understood force, but progress has been made since 1998. Video is long, but panel commentary is very interesting imo. http://pdvod.new.livestream.com/events/00000000003e0055/a7e1cbca-faa0-4b68-8689-6096c858a39e_678.mp4?start=1298&end=6900&__gda__=1434172981_c0fafb8efe0110980ff2e55b4730aa11

And would you post a link to "thread 2" as I have no idea where to view your meep posts.

Re. the Baby EmDrive data: if friction be modelled going as w^{2}, then in the absence of a driving forcew(t) -> e^{-t}Unfortunately, the shape of that does not fit the shape of the undriven data, which is roughly a straight line of negative slope.Therefore the friction model isn't right.Neither does friction going as w fit: it yieldsw(t) -> 1/(1 + t)The friction model which fits the data is constant frictional force, independent of the rotational velocity.I've already analysed that and shown that the driving force cannot be determined without more data about the experiment. Specifically we need to know eithera) the frictional torque, orb) the moment of inertia of the cavity platform (I) AND the lever arm (R) of the cavityIn any case, I am abandoning the w^{2} friction model.