I have not analyzed Shawyer's cavity design to understand what resonant mode is responsible for his thrust, and what other resonant cavity modes are supported by the cavity. The microwave oven magnetron can be pulled in frequency somewhat by a highly coupled resonant mode. You want to make sure that the magnetron is exciting the correct mode - the one that produces the thrust. The magnetron will have an output waveguide that will have to be coupled to the resonator through a port in the cavity, but an orifice may be needed at the entrance to the cavity, and tuning screws between the magnetron and the cavity to adjust the match to the residue of the desired cavity mode. You will need a small microwave probe that can preferentially detect the field in the desired cavity mode chosen to be at a field node for the other cavity modes. You would tune the match and orifice size to maximize the intensity in the desired thrust-providing cavity mode.
This optimization will not be a trivial job, but will result in maximum thrust for a given power. Other thing to note is that the microwave oven magnetron power supply is DC, but not constant DC. Usually microwave oven power supplies are just half wave rectified AC with the magnetron on for 1/2 cycle, and the driven half cycle is a half sine of DC. The frequency of the magnetron will change with the DC voltage in the half sine if there is not something, like a coupled cavity mode, to stabilize it. If Shawyer's cavity has multiple close-in modes, the magnetron, driven as a half sine voltage sweep could jump between modes as a function of voltage. It may be more desirable to modify the supply to have a lower constant voltage than having a peak half sine voltage. That will keep the magnetron from pulling off of the desired thrust mode. On Thu, Mar 17, 2016 at 7:22 PM, Russ George <russ.geo...@gmail.com> wrote: > Agreed the largest added Q comes from super-cooling. I had asked about > silver over copper as it is very simple and inexpensive to electroplate > silver onto a copper EM Drive. Building a LN2 cooled EM Drive has all > manner > of engineering issues. Perhaps the 6% added thrust from silver plated > copper > is observable and sufficient to prove the Q effect. The next issue is what > is the ideal microwave electronics and antennae design, as in what > brand/model of microwave oven do I buy to cannibalize for parts. >
