I learned about the EM drive earlier this year, and I think that if you replace the magnetron with a tesla coil it will work so well (once properly tuned) that it can produce sufficient thrust to overcome gravity. You may recall my series of posts about physics and gravity from earlier this year? I have an actual model of how it all works, not just this device but how gravity works and this is why this type of device works (chaotic electrons in tiny tiny chaotic orbits, like super high frequency, are present within all examples of thermal expansion as a precursor to the release of heat - my theory is that the expansion is not caused by the heat but by the electrons).