Would this even be plausible?
Honestly, not really. High power RF is already a pretty tough place to start as a self professed n00b, and trying to make a GHz square wave generator with a HEMT half bridge is going to be... really hard. Doing blind without a suitable instrument to actually see it working is going to be pretty much impossible.
Also, all the stuff about high duty cycle square waves is just voodoo nonsense (along with the rest of EmDrive). With no principle of how it should work or clear demonstration of it doing anything other than generating a lot of heat, things like wacky drive waveforms (that make no difference to a cavity anyway), are just needless complications to confuse people.
Ya, no scope, that would be very hard. There's no backyard hilbilly shadetree DIY workaround with a 300 MHz scope? I kinda figured there wouldn't be.
If I were to start working on this, I probably would have to rent a scope that could handle it.
Square waves are actually the most efficient input waveforms for resonant converters.
As to the duty cycle, you are correct, I did not say the terminology right. It's not duty cycle, it's duty factor, sorry.
Duty factor being the amount of time on(+&-) / total time of the period.
The higher the duty factor, the more efficient the output.
The voodoo of the EmDrive is another story.
There is no set understanding, but some,
2.4 Ghz and a frustum made out of copper.
Everyone seems to be using the method of creating RF power using Magnetrons, which are actually not that efficient, and have sinusoidal output. Magnetrons also only have one output frequency so the resonant cavity would have to change for the inputs signal.
If the input waveform could be changed to a AC square wave, using a lead follower orientation (half bridge), along with a variable duty factor, frequency, and amplitude, the efficiency would increase drastically simply by the driving circuits, along with a versatility of having variable frequency, the input signal could match the cavity instead of the other way around. The variable duty factor is so that the bridge can be adjusted to limit the switching losses.
Do you have experience with HEMTs?