Your acrobatics level has increased ! <| sep |> 1 . What you can see is defined as visible , yes . What ' s visible mostly is what we evolved to because those are the predominant wavelengths on Earth . Otherwise what we call visible light is nothing special . If you evolved on a planet around a red giant or blue dwarf , visible would probably be a different range of wavelengths . 2 . The implementation is very different because of what is humansized to make that responds to a wavelength and what is not . You use antenna for RF and optics for light . But strictly , in recent years we ' ve been able to make tiny antenna so small the light can be absorbed like RF antenna which has been proposed as a type of solar energy receiver . 3 . Yes . they are called RFmicrowave w a veguideswaveguidestosxiax 1 iaimages . The physical dimension must be ~ 12 wavelength on the short axis . Strictly for very low frequencies long wavelengths , the Earth itself combined with the ionosphere both relatively conductive act as a giant waveguide to radio because the distance between the Earth and ionosphere is ~ 121 wavelength . Technically a fiber optic cable is a type of waveguide .