radn - reco
- radnote
- radome
- radome-thermal insulation
- radome-transmission loss
- RAG
- rail
- railway center radio network
- railway communication network
- railway radio station
- railway radio station control board
- railway telegraphy
- railway telephone communication
- railway telephone network
- railway-crossing communication equipment
- rain loss
- rain returns
- rain scattering
- RAINBOW
- rainfall absorption
- RAM
