My weather station is a Raspberry Pi 3B in a steel electrical box on the garden shed wall, about 25 m from the house. It reports wind, rain and temperature every minute.
Since I moved it from the kitchen windowsill to the shed it keeps going offline. The device’s Log tab in Hermetry is full of disconnects with reason keepalive_timeout, then a reconnect a few minutes later. On the Pi, iwconfig wlan0 shows a signal level around -82 dBm, sometimes worse when the box door is shut.
I’ve seen photos of people soldering an antenna connector onto the board. Has anyone done that on a Pi 3? I own a soldering iron and some confidence, not much more.
There are guides for some boards where you move a tiny 0402 part to route the radio to an external connector. Not sure the Pi 3 even has that pad though, I’d check before heating anything.
I’m new to IoT but we had exactly this with a Pi in a steel box in our hotel’s pool plant room. Our IT guy talked me out of soldering. A closed steel box is close to a Faraday cage, so the onboard chip antenna inside it will always struggle, and the Pi 3 is not designed for an external one.
What we did instead, cost about 20 dollars:
- A USB Wi-Fi adapter with an RP-SMA connector.
- A short RP-SMA extension cable through a cable gland in the box, antenna mounted outside on top.
- Onboard Wi-Fi switched off so the dongle is the only wlan0. Add
dtoverlay=disable-wifito config.txt and reboot. Then put your Wi-Fi settings on the dongle as usual.
Our signal went from about -84 to -58 dBm.
On the Hermetry side I also lengthened the offline alarm. The docs suggest an Open after time longer than a normal reconnect for devices that can drop briefly, we use 600 s, so a 30 second Wi-Fi dip no longer wakes anyone. Keepalive is 60 s in our script.
Dongle route it is. Antenna on top of the box, onboard Wi-Fi off, signal now -61 dBm with the door shut. No keepalive disconnects in the Log tab since Saturday, and I kept the soldering iron in the drawer. Had to install the driver for my dongle first, it was a RTL8812AU one, so check yours is supported before buying.
Good to know the dongle way works, much less risky than my 0402 idea.
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