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Opus in profectus

Electromagnetic Spectrum

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introduction

A good, general sequence to remember is radio waves, microwaves, infrared, light, ultraviolet, x-rays, gamma rays

Spectrum chart

micropulsations

Less than 3 Hz is subradio, micropulsations, or another name.

radio waves

3 Hz–3 THz seems to be the agreed upon range of frequencies.

Radio frequency bands International Telecommunication Union Since 2015 these designations are no longer endorsed by the ITU, but I think they should be. They give the table a pleasing symmetry. They are also still sometimes used by scientists and engineers. This designation is not endorsed by the ITU, but I think it should be. The "t" in tremendous matches the "t" in terahertz (the geometric mean of the band), matches the "t" in twelve (1 THz = 1012 Hz), matches the "t" in trillion (1012 is also known as a trillion).
name ITU* number frequency wavelength
extremely low frequency (ELF) 1 (~1010 Hz) 3 30 Hz 100,000 10,000 km
super low frequency (SLF) 2 (~1020 Hz) 30 300 Hz 10,000 1,000 km
ultra low frequency (ULF) 3 (~1030 Hz) 300 3,000 Hz 1,000 100 km
very low frequency (VLF) 4 (~1040 Hz) 3 30 kHz 100 10 km
low frequency (LF) 5 (~1050 Hz) 30 300 kHz 10 1 km
medium frequency (MF) 6 (~1060 Hz) 300 3,000 kHz 1,000 100 m
high frequency (HF) 7 (~1070 Hz) 3 30 MHz 100 10 m
very high frequency (VHF) 8 (~1080 Hz) 30 300 MHz 10 1 m
ultra high frequency (UHF) 9 (~1090 Hz) 300 3,000 MHz 1,000 100 mm
super high frequency (SHF) 10 (~1010 Hz) 3 30 GHz 100 10 mm
extremely high frequency (EHF) 11 (~1011 Hz) 30 300 GHz 10 1 mm
tremen­dously high frequency (THF) 12 (~1012 Hz) 300 3,000 GHz 1 0.1 mm

microwaves

Short (less than a meter) to teeny tiny (but not less than a tenth of a millimeter) wavelength radio waves. The high frequency side of the radio spectrum 0.3–3,000 GHz. Where the microwaves end and infrared begins is open to some debate however.

Diagram

Text

Circuit diagram

Equivalent Circuit Diagram

Equivalent circuit diagram

Diagram from Percy Spencer's 1945 US patent for the microwave oven. Note the popcorn kernel labeled "Food to be Cooked".

Radar frequency bands (radiolocation services, *except where indicated) 1Institute of Electrical and Electronics Engineers 2International Telecommunication Union 3International Organization for Standardization *Space radiocommunication Unconfirmed German for short §2.700–3.600 in the Americas 5.250–5.850 in the Americas
frequency range (GHz)
band name IEEE1 ITU2 ISO3
  HF   high fre­quency 0.003 0.030 0.002 0.040      
VHF very high fre­quency 0.03 0.3 0.138
0.216
0.223


0.144
0.225
0.230
     
UHF ultra high fre­quency 0.3 1 0.420
0.890

0.450
0.942
     
P pre­vi­ous 0.216 0.450       0.225 0.390
L long 1 2 1.215
1.525

1.400
1.710*
0.39 1.55
S short 2 4 2.300
2.500
2.700


2.500
2.690*
3.700§
1.55 5.2
C compro­mise 4 8 3.400
4.200
4.500
5.250
5.850




4.200*
4.400
4.800*
5.925
7.075*
3.9 6.2
X crosshair 8 12 8.500 10.680 005.2 10.90
uKu kurze under 12 18 10.700
13.400
14.000
15.400



13.250*
14.000
14.500*
17.700
     
K kurze 18 27 17.700
24.050
24.650


20.200*
24.250
24.750
10.9 36
aKa kurze above 27 40 27.500
33.400

30.000*
36.000
     
Q               36 46
V   40 75 37.500
47.200

59.000


42.500*
50.200*

64.000
46 56
W   75 110 76.000
92.000

81.000
100.000
56 100
mm milli­meter 110 300 136.000
151.500
231.000
238.000



148.500
155.500
235.000
248.000
     
THz tera­hertz 3000 1000          

The traditional radar band names (L, S, C, X, Ku, K and Ka) originated during World War II as a secret code so scientists and engineers could talk about classified frequencies without divulging them. After the war the codes were declassified and the Q, V, W, and millimeter (mm) bands were added. The designations were eventually adopted by the Institute of Electrical and Electronics Engineers (IEEE — read as "I triple E") in the United States, and internationally by the International Telecommunication Union (ITU) and International Organization for Standardization (ISO).

infrared (a.k.a. "infrared light")

Literally "below" red. So anything shorter than red light (700–800 nm or ~400 THz), but not so short that you could build an oscillating circuit transmitter; i.e., a radio (1 mm or 3 THz). Actually, the longer wavelengths kind of drip over into microwaves.

light (a.k.a."visible light")

Roughly 400–700 nm

ultraviolet (a.k.a. "ultraviolet light")

Literally "beyond" violet. So shorter than say 300–400 nm. Somewhere around there. Down to as short as 0.1 nm. Ultraviolet and x-rays overlap. Whether you call it ultraviolet or x-rays depends on the application.

x-rays

The range of wavelengths here is 10−8 m down to 10−12 m, with the long end overlapping the ultraviolet and the short end overlapping gamma rays,

gamma rays

Everything shorter than 10−11 meter. How much shorter? Good question.