[20220125]IF11155_防务基础：电磁频谱的军事用途.pdf

https:/crsreports.congress.gov Updated January 25, 2022Defense Primer: Military Use of the Electromagnetic SpectrumSince the introduction of the two-way radio in the early 1900s, militaries have been interested in the electromagnetic spectrum (“the spectrum”). The proliferation of spectrum-dependent systems in all military domainsair, land, sea, space, and cyberspacealong with Department of Defense (DOD) concepts, such as net-centric warfare and multidomain battle, increases the militarys dependence on the spectrum. What Is the Spectrum? The electromagnetic spectrum is a series of frequencies ranging from radio waves to microwaves, visible light, X-rays, and gamma rays. As the wavelength of the electromagnetic radiation shortens, the waves have a higher frequencyhow quickly electromagnetic waves follow each otherand therefore more energy. Figure 1. The Electromagnetic Spectrum Source: https:/imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.html. Different parts of the spectrum serve different military purposes. Radio transmissions have relatively low data ratesparticularly in the very low frequency range. However, they are able to travel long distances and pass through solid obje