Radio
"Radio waves have the longest wavelengths in the electromagnetic spectrum with wavelengths ranging from approximately 1mm to several hundred meters. Radio waves are used to transmit a variety of data. Wireless networking, television and amateur radio all use radio waves." (Humboldt State University, 2014)
Sources
"Electromagnetic Spectrum". Humboldt State Geospatial Online, Humboldt State University. 2014.
http://gsp.humboldt.edu/OLM/Courses/GSP_216_Online/lesson1-2/spectrum.h….
Accessed February 1, 2019.