This is an experiment with a 915Mhz LoRa module and SAW filters as a substitute for discrete components. The original raison d'être of this repository is my personal outrage after seeing the following $100 evaluation board for the PE4259:
And indeed, AppliedCarbon from OSHPark also thought so and designed a smaller PCB.
Gold tracks and pads, many vias and proper RF engineering, sure, but $100 plus shipping? Let's see how the homemade way works in comparison? On the master branch of this repository, I'm putting together a board with the RF switch and the SAW filter (will be using a 915 Mhz sf2098e "low insertion loss" SAW filter, no frills design for now. I might put the vias in place if needed in the future and compare performance/loss and the accompanying S parameters.
But since the approach above might not be modular enough for my testing purposes (thanks Chris), I've forked that layout into two branches:
$ git branch -a
* master
rf_switch_only
saw_filter_onlyHere's how each of those look like at the moment of writing this, let's play "spot the differences", shall we?:
Now, as with the Instructables Carvey Board project, I've generated some G-Code (under the homefab subdirectory) with FlatCam to carve those board at home, wish me luck with the spectrum analyzers and followup testing!
Alternatively, there's a .zip under homefab, containing the ready-to-send gerbers to i.e Seed Studios or any other PCB manufacturer. Here's the latest iteration of the rf matching board on master:
