Please help me to "decypher" simple 10GHz RF module

[Alexei.Polkhanov]

I got an ebay item that I have purchased just out of curiosity - it is a cheap 10GHz RF module which I believe was designed to supplement IR sensors in automatic door openers and things like that. I removed the shielding and I found PCB with bunch of micro-strip elements and few surface mount components. Most of the stuff (I think) make sense to me - like stubs for impedance matching, island to remove reflections but some does not. I don't understand the purpose of white ceramic component in the top right corner. It is not connected electrically to rest of components on top layer and also shield has a metal screw position on top of it for what appears to be fine tuning. What is it for? What does it do? Perhaps someone with more microwave experience can explain me this design?

I found some datasheets and photos attached.

[Rory]

This is a dielectric resonant oscillator. The white ceramic puck is the element that determines the frequency of the oscillator.

http://en.wikipedia.org/wiki/Dielectric_resonator

[Alexei.Polkhanov]

I see, that screw in a shield box is a magnet that creates magnetic field and makes it to resonate. Make total sense now. And the black 4-lead component next to it is an amplifier.
I wonder if the fact that it (oscillator) is not electrically connected to amplifier s by design or is a defect of my unit. I understand that at microwave frequencies a tiny gap in a track on pcb will effectively work as capacitor, but usually it is better defined than in this case.

[KJDS]

The white cylinder is a resonator. Think of it as a shunt LC element. It is coupled to the input line of the amplifier that is next to it to form an oscillator. The screw will adjust the frequency. Just because things aren't touching doesn't mean they aren't connected. Just think how a capacitor works where you also don't have the two terminals touching.