A FLARM system is normally installed in certified aircraft. Approved antennas are usually listed in the installation instructions. For PowerFLARM Core, this is part of the EASA approved Minor Change. For most aircraft, the FLARM AV-75 antennas should be used for external mounting. Glassfiber gliders can also use internal antennas.
More information about antenna selection and installation can be found in the document "FTD-041 Application Note FLARM Antenna Installation", which can be found on the Manuals and Documents page.