Radio frequency modulation Fiber optics 20 Microwave communication systems 20 Optical communications 20 Receivers and reception 10 Transmitters and transmission 8 Modulation (Electronics) 6 Radio 6 Monopole antennas 5 Computer programs 4 Radio detectors 4 Antenna radiation patterns 3 Cellular telephones 3 Telecommunication 3 Wireless communication systems 3 Antennas (Electronics) 2 Data transmission systems 2 Digital to analog converters 2 MP3 (Audio coding standard) 2 Microcontrollers 2 Music 2 Phase-locked loops 2 Transmitter-receivers 2 Transmittors and transmission 2 Walkie-talkies 2 Aids and devices 1 Amateur radio stations 1 Amplitude modulation 1 Antennas 1 Business logistics 1