Aerial replacement on ESP32 C3 Zero - Page 1
Forum section: electronics / rf-microwave

author: msknight
author_rank: Regular Contributor
timestamp: January 04, 2025, 08:40:18 am
content: I'm doing a project on an ESP32 C3 Zero board. It is too far away to talk with the wifi and I need to replace the on board small chip aerial with something meatier. Picture in attachment.https://www.waveshare.com/wiki/ESP32-C3-ZeroI do have some u-fl aerial cables, but I haven't got a clue how to connect this to the board. Grateful for any suggestions.https://uk.farnell.com/multicomp-pro/r-134g7210150ca/cable-u-fl-sma-rp-150mm-50ohm/dp/1699261?CMP=e-email-sys-orderack-GLB

author: geggi1
author_rank: Frequent Contributor
timestamp: January 04, 2025, 04:36:50 pm
content: As far as i see you have a few options.Do you need to use 2,4 Ghz wifi? If you can use a bord on 400 or 800 Mhz other antennas can be used and the range will be longer.Cut the UFL of the pigtail and strip the coax and solder everything. This will be tricky because of fine strands and thin cable. The existing chip antenna must be removed.Remove the chip antenna and solder a UFL socket to the board. You must have a steady hand with good light and magnification. If you have problems finding the UFL socket a option might be to scavenge one in a old WIFI router.

author: msknight
author_rank: Regular Contributor
timestamp: January 04, 2025, 05:47:51 pm
content: Yes, I need to stay on 2.4ghz for ESPHome and the boards that are majority used for that.I'd actually be more comfortable with a socket than stripping and soldering the wires. Finding an appropriate socket to bridge that gap is proving difficult though. If I do have no other choice than to solder the wires, I don't believe there is any polarity to deal with here?

author: shabaz
author_rank: Frequent Contributor
timestamp: January 04, 2025, 06:44:32 pm
content: It might not be all that effective, because the coax and antenna will have 50 ohm impedance, whereas the board antenna will be something different, and there is a bit of matching circuitry on the board. You could give it a shot if you're intent on it, it might work 'good enough' but really it's sub-optimal.There are at least a couple of other options that may be worth considering, if that doesn't work:(a) simply move the entire ESP32 board closer to your WiFi access point, and extend the power and digital I/O connections to the rest of your project. This may cause other issues, but some of them may be solvable easily (not all).(b) use a ESP32 board that has an antenna socket on-board, since then the board will be designed to expect a 50-ohm impedance. A possible replacement may be Seeed XIAO ESP32C3 (I have not used these boards, so I don't know what other differences there are; it's unlikely all the same ports are exposed as connections, and the Seeed board looks like it may have less connections, so if your project needs a lot of I/O, then it may not be suitable.

author: msknight
author_rank: Regular Contributor
timestamp: January 04, 2025, 10:22:29 pm
content: The unit will be in the garden (rain sensor) so I can't really decrease the distance... but the Seed Studio board might actually do the job. I'll get one and see if it will work. I only need two analogue inputs and one digital output.Thanks for the suggestion. That might be just the ticket.

author: phansel
author_rank: Contributor
timestamp: January 05, 2025, 02:29:57 am
content: Many products just use a wire whip antenna with a conductor at the quarter wavelength. Sometimes it's an exposed conductor outside a length of coax, other times it's just a single wire soldered to the board. That'd be about 3.06cm at 2.45 GHz.If you need something more directed, a 2.4 GHz patch (e.g. Taoglas FXP810.07.0100C available at Farnell) would probably work.Quote from: msknight on January 04, 2025, 05:47:51 pmIt might work with shield and signal swapped, but you'd typically solder the wire shield/braid to ground (the via stitched plane) and the wire core to the signal trace.