The IC is this one – https://www.silabs.com/documents/public/data-sheets/Si4012.pdf
It seems i have set it up correctly according to its I2C dialog with the MCU, but nothing gets received by my SDR.
P.S. @downvoters: why the hate ?
Got an answer for the hate, and more hate, excellent!
Surely enough I've spent some hours on the internet trying to figure whether these things can work without any antenna or not. Obviously with no luck. And no, the pdf linked here does not clearly make it obvious to everyone that the damn antenna can not be skipped. Actually there are a some separate pdf files describing how to make the trace antenna for this chip. I guess everybody knows, sure. Here is another link with me asking in their forums yesterday – https://community.silabs.com/t5/Proprietary/Si4012-with-chip-antenna/m-p/195937/highlight/true#M2987
Anyway, short and to the point post, maybe from a phone while in the subway ? Nah, hating is more fun.