GPIO / Antenna Connection - Direct RF Connection?

Sub-GHz
#1

I’m wondering if it’s possible to directly connect antennas to the GPIO RX/GND pins or is an external RF IC necesary?

I want to design a few different antennas with high efficiency on specific bands/frequencies, ie. a yagi or array optimized for specific sections of UHF.

If so, are there any drawbacks specific to the flipper that would cause issues with this (harmonics or noise issues without a proper filter?)?

If not, what modules are there that can either be purchased with an SMA/BNC/PL239 connector, or have open source schematics that I can build myself without any obscure ICs?

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#2

Look at the schematics, just after the balun before the auto tuning network you can add external antenna. If you are not into surface mount soldering there are other external RF modules that plug into the gpio port.

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#3

There are ways to make a wire attached to the GPIO pins transmit but it would only be transmit and likely be inferior to the internal radio. Things like amplifiers and filters would be needed to clean the signal. There are lots of people making diy add in devices though that work quite well. They use real transmitters similar to what is in the Flipper.

The mains modules I see are ESP, NRF, and the CC1101 that the Flipper uses internally. Some even have amplifiers.

#4

I bought an Antenna. You also can build one for 1/5 of the costs of a Finnish antenna. You just need a C1101 module for 2,50 USD and a antenna for 5 USD.
Or you can a Finnish one here:

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