Radio-frequency engineering

Radio-frequency (RF) engineering is a subset of electrical engineering involving the application of transmission line, waveguide, antenna, radar, and electromagnetic field principles to the design and application of devices that produce or use signals within the radio band, the frequency range of about 20 kHz up to 300 GHz. It is incorporated into almost everything that transmits or receives a radio wave, which includes, but is not limited to, mobile phones, radios, Wi-Fi, and two-way radios.

Source: Wikipedia — Radio-frequency engineering (CC BY-SA 4.0)