Due to the assumption of the impact on Q regarding small end below cutoff I did a few short sims using FEKO.

What I found is surprising but thats the result. It implies, that Q is higher in the case with the undersized small plate.

The only differences are the cavity size itself and an adjustment of the loop antenna to get an reflection coefficient less than 0.1 (linear magnitude).







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We show that a light pulse is associated with a mass density wave (MDW). We also prove that the transfer of mass with the light wave, the photon mass drag effect, gives an essential contribution to the total momentum of the light wave, which becomes equal to the Minkowski momentum.

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The same kind of description can be used for electromagnetic wave propagation in a waveguide. The effective mass of the confined photons will then be equal to meff = ω0/c2, where ω0 is the cut-off frequency for the specific mode of

propagation.

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Eq. (47) is called the Dirac-like equation of photons with the effective mass m.

I wanted to address a lot of the comments here but your image makes a good illustration of the two cone types. We can easily see that current will be stimulated on the end plate in the short configuration while no current is stimulated on the small end plate of the cone.The definition of Q or quality factor is given on wiki for quick reference: https://en.wikipedia.org/wiki/Q_factor Notice as Rodal pointed outwith increased current on the end plate [power loss=I^2*R] this lowers Q as is in the equation of Q. With the tall cone geometry there is probably less current loss at the small end because the end plate is not stimulated as with the short cone [frustum]. Hence the Frustum may have lower Q because of increased power loss at the small end plate? Not sure this is certainly true but it is interesting if it is the case.There is pressure on the side walls. I think I even remember TT admitting this. His last cone ray diagram admits the side wall pressure as well as I remember him admitting it earlier. If we continue the change in angle of the photon it returns to the big end plate.There seems to be a cutoff where radiation can not penetrate beyond a certain small diameter in a cavity. This is analogous to a microwave cavity that cooks burritos, that has small holes that can be open and radiation doesn't seem to pass through the holes in a significant manner. It should be due to absorption of the energy from light back into the metal as evanescent waves that decay. Reflection happens here and the decay is related to skin depth I think.The increase in wavelength may indicate a decrease in the ability of light's effective mass or its ability to transfer energy but that is yet to be shown though I cite some papers in my paper that suggest so. Even with cone geometry we still get this increase in wavelength. However, the increase in Q with cone geometry narrows our bandwidth!so by df=f/Q if Q increases our df decreases with decreasedloss. See the image at the top of the Wiki to observe the bandwidth.Why is this important possibly? Because in a cavity when a photon/wave reflects from one end it loses some energy to accelerating the cavity. Upon hitting the other end [even cone geometry] if a photon/wave loses effective mass [increase in wavelength] it will not regain the energy it lost by reflecting. [even matter is a wave] See the change in the ratio of energy exchanged upon a collision in figure 1 of a 1kg mass colliding with another variable mass object.This would possibly lead to a permanent loss of frequency as defined by dE=h*df so dE decreases then df decreases and subtracts from the frequency. The mass Doppler effect from accelerating the cavity is aorder term I believe which I pulled out as the 2nd part of equation 14 goes df/f=2*mp/m2 where mp=effective mass of photon and m2=mass of object, f=initial frequency, df=change in that frequency. The first part of equation 14 [in paper] is the standard Doppler effect from reflected light df/f=2*v/c which only depends on velocity and reduces to this approximation when v2 is considered negligible to speed c for df/f=2*v2/(v2+c).So why is bandwidth important? Because if energy is lost from light in this fashion then only so much energy can be lost in such a cavity as defined by that bandwidth which is effected by Q before the light is rejected from the cavity. Therefore, it may be desirable to have those power losses or lower Q to increase bandwidth.I have yet to see any proof such an effect exists and I would hope it could be directly observed by injecting a frequency spike at the beginning of the bandwidth and looking for lower order stimulation frequencies or a spread of the injected frequency. If such a spread is observed it may be direct evidence such an effect can happen.This "may" parallel with WarpTech's theory because his seems to imply power loss may be essential. If it is the same it may be from a different viewpoint. I am not implying it is the same just that there may be such a possibility because of the similar desire forloss and not necessarily larger Q. This is also possibly why having the small end plate interacting with the inner radiation may be desirable.Not sure my paper predicts the right force because I don't take into account the limited bandwidth though I hint at it. May be mistakes in there also.I hope I didn't say too much that I bore you all to tears.cited papers:other literature cited in my paper in section: III. THEORY OF ACCELERATED LIGHT AND OTHER SOURCES .Particularly, theis very interesting and other papers found on scholar.google.com but not cited yet.