Electromagnetic spectrum
All the electromagnetic waves travel with the same velocity (i.e. 3 X 108 m/s) in the free space with different frequencies. The arrangement of electromagnetic radiations according to wavelength or the frequency is referred as electromagnetic spectrum.
As we know electromagnetic spectrum has no definite upper or lower limit and various regions of EM spectrum do not have sharply defined boundaries.
The electromagnetic spectrum types, their frequency, wavelength, source and applications have been outlined in the table below. As mentioned EM waves include electric wave,radio wave,microwave,infrared,visible light,ultra violet,X-rays,gamma rays and cosmic rays.
| EM wave type |
Frequency (Hz) |
Wave- length (m) |
Source | Applica- tions |
|---|---|---|---|---|
| Electric Wave | 50 to 60 |
5 x 106 to 6 x 106 |
Weak radiation from AC circuit |
Lighting |
| Radio Wave | 3 x 104 to 3 x 109 |
1 x 10-1 to 104 |
Oscillating circuits |
Radio communication, television |
| Microwave | 3 x 108 to 3 x 1011 |
1 x 10-3 to 1 |
oscillating currents in special vaccum tubes, Gunn,IMPATT,Tunnel diodes |
Radar,TV, Satellite communication, remote sensing |
| Infrared | 1 x 1013 to 4 x 1014 | 7.5 x 10-7 to 3 x 10-5 | Excitation of atoms and molecules | Gives information on the structure of molecules and of external atomic electron shells, remote sensing |
| Visible light | 4 x 1014 to 8 x 1014 | 3.75 x 10-7 to 7.5 x 10-7 | Excitation of atoms and vaccum spark | Gives information on the structure of molecules and of external atomic electron shells, remote sensing |
| Ultra violet | 8 x 1014 to 1 x 1016 | 3 x 10-8 to 3.75 x 10-7 | Excitation of atoms and vaccum spark | Gives information on the structure of molecules and of external atomic electron shells, remote sensing |
| X-ray | 1 x 1016 to 3 x 1019 | 1 x 10-10 to 3 x 10-8 | Bombardment of high atomic number target by electrons | X-rays therapy, industrial radiography, medical radiography, crystallography |
| Gamma Ray | 3 x 1019 to 5 x 1020 | 6 x 10-15 to 1 x 10-10 | Emitted by radioactive substances | Gives information about the structure of atomic nuclei |
| Cosmic Ray | > 1020 | < 10-11 | Stars from other galaxies |
The figure-1 depicts electromagnetic spectrum or EM spectrum with various waves as mentioned in the table above.
More RF Links
RF converter design
C band RF Transceiver basics
RF filter design
RF vector Signal generation/analysis
Microstrip line basics
RF and SoC Testing
rf connector
Rectangular Waveguide
RF Terminologies
what is RF