There sure are a lot of contacts on the bottom of the chip, though!
Edit: After looking at this picture for a while it looks like It's not just GND, but there is some real RF VooDoo going on.
The rows of 2x17 bumps on the underside are probably for communication.
I am sort of surprised about the sharp 45 degree corners on the antenna's. I would have expected round curves there.
A few years ago I read an article about design of a radar device. They had lots of problems with internal reflections from the sides of PCB traces. It turned out it was impossible to etch the PCB and they had to mill the PCB to make the sides of the PCB traces perfectly flat and regular to minimize reflections.
And in a few years this will be an EUR 5 gadged in your wristwatch.
Now my imagination takes over. How about using this for a doorlock. Then you can pull the weirdest faces in front of your front door or practice with the ministry of silly walks to gain admittance to your residence.
Doing magic with a USD 7 Logic Analyser: https://www.avrfreaks.net/comment/2421756#comment-2421756
Bunch of old projects with AVR's: http://www.hoevendesign.com
No doubt the radiations will give you finger cancer.......
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It seems that the hardware is made Inineon, and Google did the software magic to make sense of the sensor data.
On the Inineon link you can find some description of this footprint.
The 4 sqares on top are the receiving antennas, and the 4 ears on the side are transmitting antenna's.
Some of the bumps on the undersed are marked as an "SPI interface".
I made a new post because editing a post with such a big inline pasted picture is extremely slow to edit with my old poor dualcore pc (It's from 2008, > 10 years old now!).
Editing such a post seems to download mulitble MB of gibberisch (Base-64 inline picture) into an edit window.
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