Part 4: Front antenna

A project log for Tesla Key Watch

Embedding a J3A040-CL chip and a custom antenna into a modified Casio F-91W for accessing my Tesla Model 3.

Mattia Dal BenMattia Dal Ben 09/02/2020 at 17:370 Comments

So... I got an idea for improving the watch mod.

The original idea by N-O-D-E was to put the antenna behind the frontplate using a PCB antenna, which is great but leave me no room for resonant frequency tuning. What if I can tune the antenna anyway?

The idea is the following: what if we can build an antenna using the above part as a guide and as the front plate? Showing off the back of the chip (which is awesome) and leaving all the room needed for the tuning?

But Mattia, you say, how do you protect the watch now that we have a big gaping hole in front of the screen?

UV curable resin.

This will cure perfectly clear and fill all the needed gaps, with the added benefit of making the frontplate and the antenna a whole thing.

But Mattia, you say, how do you glue this new frontplate to the watch?

2mm wide double-sided tape usually used in smartphone repair (again thanks to N-O-D-E for the idea).

This new design should solve almost all the shortcomings of the old version:

Let's see if it can actually be done...