I converted a hotwheels car into an RC car using a DRV8833 H-bridge, a small DC motor, a 1.5g linear servo, and a XIAO ESP32c3, with a 3d printed steering linkage. It’s been a really fun project, but one part I’m still stuck on is the antenna.
The XIAO is nice and tiny, but it has a big external antenna. I haven’t found a good way to fit this antenna on the tiny car, so I’d like to replace it with something smaller. But searching for 2.4 Ghz U.FL antennas turns up a lot of even bigger options. I don’t need all that much range, but definitely more than I can get without an antenna.
I don’t know a lot about RF and antennas, but I think I understand that all I really need is a bare wire cut to the length of speed_of_light/frequency, so 300000/2400, or half or a quarter of that. So that’d be 125mm, 62.5mm, or 31.25mm.
Where I haven’t connected the dots yet is that the U.FL connector on the XIAO is coaxial, so there are two conductors. Which of these conductors should I connect to a bare wire of the correct length? What, if anything, should I connect to the other conductor?
When I look at the antenna that comes with the XIAO, it kinda looks like both conductors connect to the antenna, at the points circled:
So it makes a ~54mm loop between the two connections, and then a few funky branches from each connection. Maybe the length of all of the branches and the loops add up to 125mm? In that case, do I just connect both conductors to my bare wire antenna? Or am I barking up the wrong tree?
Thanks for any help!