amateur radio astronomy astrophysics atmospheric window atom bandplan black hole blue c band centimetre coil compton scattering dna digital object identifier diode dipole moment ehf electrical conductor electromagnetic radiation electromagnetic spectroscopy electron energy extremely high frequency extremely low frequency frequency frequency allocation gamma ray green gunn diode hertz high frequency hydrogen impatt diode industry canada infinity infrared iron k band kilometre klystron l band longwave low frequency luminosity function medium frequency medium wave microwave microwave oven mobile phone modulation mutagen nanometre national radio astronomy observatory neutron star octave ofcom optical fiber ozone layer paul ulrich villard photon physical cosmology planck length q band radiant energy radiation radio radio frequency radio waves rainbow red resonance shf s band shortwave skin skin cancer skin effect spectroscopy speed of light star sun sunburn super high frequency super low frequency television terahertz radiation ultra high frequency ultra low frequency ultraviolet united states department of commerce universe v band very high frequency very low frequency visible spectrum visual perception w band waveguide wavelength wi-fi wikimedia commons x-ray x-ray machine x band yellow