FREQUENCY SPECTRUM
Figure 1, which follows, depicts the electromagnetic radiation spectrum and some of the commonly used or known
areas. Figure 2 depicts the more common uses of the microwave spectrum. Figure 3 shows areas of the spectrum which
are frequently referred to by band designations rather than by frequency.
Section 7-1 provides an additional breakdown of the EO/IR spectrum.
To convert from frequency (f) to wavelength (8) and vice versa, recall that f = c/8, or 8 = c/f;
where c = speed of light.
8meter '
3x10 8
3x105
300
0.3
'
'
'
f Hz
f kHz
f MHz
f GHz
or
f Hz '
3x10 8
8meter
f kHz '
3x105
8meter
Some quick rules of thumb follow:
Metric:
Wavelength in cm = 30 / frequency in GHz
For example: at 10 GHz, the wavelength = 30/10 = 3 cm
English:
Wavelength in ft = 1 / frequency in GHz
For example: at 10 GHz, the wavelength = 1/10 = 0.1 ft
Figure 1. Electromagnetic Radiation Spectrum
2-3.1
f MHz '
300
8meter
f GHz '
0.3
8meter
0.3
0.4
0.5 0.6
0.8
1.0
GHz
2
3
1m
4
5
6
8
10
GHz
20
30
10 cm
40
50 60
80
100
GHz
1 cm
Figure 2. The Microwave Spectrum
FREQUENCY (MHz)
20
30
100
200
300
FREQUENCY (GHz)
500
1.5 2
3 4 5 6 8 10 15 20 30 40
12 18 27
60 80 100
200 300 400
110
VHF
HF
UHF
L
C
S
X
K*u K
K*a
U.S. INDUSTRY STANDARD BANDS (IEEE Radar Designation)
7 (HF)
8 (VHF)
9 (UHF)
V
10 (SHF)
W
11 (EHF)
INTERNATIONAL STANDARD BANDS
250
A
B
C
D
E
F
G
H I
J
K
MILITARY STANDARD BANDS
* "u" stands for unabsorbed or under K; "a" stands for absorption region or above K
Figure 3. Frequency Band Designations
2-3.2
Millimeter
L
M
12