Links:

https://oshwlab.com/jyesmith/expresslrs-gemini-tx

https://www.expresslrs.org/

https://www.expresslrs.org/hardware/special-targets/diy-tx/

https://www.skyworksinc.com/-/media/SkyWorks/Documents/Products/2901-3000/SKY65383-11_202668G.pdf

https://oshwlab.com/jyesmith/kv-meter

https://oshwlab.com/jyesmith/expresslrs-gemini-tx_copy

Design Notes/Justifications

Via Sizing & Stitching

The following app note was referenced for stitching the GND pours around the RF sections: https://www.infineon.com/dgdl/Infineon-AN91445_Antenna_Design_and_RF_Layout_Guidelines-ApplicationNotes-v09_00-EN.pdf?fileId=8ac78c8c7cdc391c017d073e054f6227

• Larger vias used for the stitching to provide more copper, providing better conduction capacity & continuity between planes (larger hole size = more copper around circumference of cut through plane)

• Smaller vias used for signals and other areas to make it easier to fit vias closer together, i.e. for ESP signal fanout, due to large hole to hole clearance of 0.5mm required by JLCPCB

Parts from https://oshwlab.com/jyesmith/expresslrs-gemini-tx

E28-2G4M27S

https://www.lcsc.com/product-detail/Wireless-Modules_Chengdu-Ebyte-Elec-Tech-E28-2G4M27S_C411312.html

E28-2G4M12S

https://jlcpcb.com/partdetail/Chengdu_Ebyte_ElecTech-E282G4M12S/C411310

ESP32-Pico-d4

https://www.digikey.ca/en/products/detail/espressif-systems/ESP32-PICO-D4/9381722

ESP-01f

https://www.waveshare.com/w/upload/3/31/ESP-01F-datasheets.pdf

Parts from https://oshwlab.com/jyesmith/expresslrs-gemini-tx_copy

ESP32-Pico-d4

https://www.digikey.ca/en/products/detail/espressif-systems/ESP32-PICO-D4/9381722

ESP-01f

https://www.waveshare.com/w/upload/3/31/ESP-01F-datasheets.pdf

WIRELESS-LORA-RFM95W

https://www.adafruit.com/product/3072