Doppler Array Units

I've used a number of the little 10 GHz Doppler array units for motion sensing. I buy the raw unit and ginned up my own filter/amplifier for it. Well, as will always happen eventually, I cooked one, so I decided to pry off the little can on the back and take a look.

Amazingly, inside there is one little cylinder about the size of an aspirin, two (apparent) capacitors, and a couple of 4 -pin very small gadgets. Above the little cylindrical element is a set screw, which is hidden below the inspection sticker normally seen on the outside of the can. The interesting thing is, the set screw doesn't actually turn anything: it can only vary the pressure on top of the little cylinder.

Curiosity makes me ask if anyone out there knows how this technology works, and what does the set screw actually adjust?

Thanks in advance for any insights.

Standard microwave circuitry - there is likely a Gunn diode as an oscillator and some sort of mixer. The set-screw will be tuning a cavity no doubt.

Microwave circuitry is either waveguide based like here, or stripline/microstrip on PFTE circuit boards. Most microwave components are though of as "exotic" to other electronic disciplines!