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12 Introduction Chap. 1 TABLE 1–2 (cont.) Frequency Band a Designation Propagation Characteristics Typical Uses 0.3–3 GHz Ultrahigh frequency (UHF) Letter designation 1.0–2.0 L 2.0–4.0 S 3–30 GHz Superhigh frequency (SHF) 2.0–4.0 4.0–8.0 8.0–12.0 Letter designation S C X 12.0–18.0 Ku 18.0–27.0 K 27.0–40.0 Ka 26.5–40.0 R 30–300 GHz Extremely high frequency (EHF) Letter designation 27.0–40.0 Ka 26.5–40.0 R 33.0–50.0 Q 40.0–75.0 V 75.0–110.0 W 110–300 mm (millimeter) 10 3 –10 7 GHz Infrared, visible light, and ultraviolet a kHz = 10 3 Hz; MHz = 10 6 Hz; GHz = 10 9 Hz. LOS propagation, cosmic noise LOS propagation; rainfall attenuation above 10 GHz, atmospheric attenuation because of oxygen and water vapor, high water-vapor absorption at 22.2 GHz Same; high water-vapor absorption at 183 GHz and oxygen absorption at 60 and 119 GHz LOS propagation UHF television, cellular telephone, navigational aids, radar, GPS, microwave links, personal communication systems Satellite communication, radar microwave links Radar, satellite, experimental Optical communications For a detailed chart of current frequency allocations in the United States see http://www.ntica. doc.gov/osmhome/allochrt.html. 1–8 PROPAGATION OF ELECTROMAGNETIC WAVES The propagation characteristics of electromagnetic waves used in wireless channels are highly dependent on the frequency. This situation is shown in Table 1–2, where users are assigned frequencies that have the appropriate propagation characteristics for the coverage needed. The propagation characteristics are the result of changes in the radio-wave velocity as
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- Page 34: Preface xv THE PRACTICAL APPLICATIO
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12 Introduction Chap. 1<br />
TABLE 1–2<br />
(cont.)<br />
Frequency<br />
Band a<br />
Designation<br />
Propagation<br />
Characteristics<br />
Typical Uses<br />
0.3–3 GHz Ultrahigh<br />
frequency (UHF)<br />
Letter designation<br />
1.0–2.0 L<br />
2.0–4.0 S<br />
3–30 GHz Superhigh<br />
frequency (SHF)<br />
2.0–4.0<br />
4.0–8.0<br />
8.0–12.0<br />
Letter designation<br />
S<br />
C<br />
X<br />
12.0–18.0 Ku<br />
18.0–27.0 K<br />
27.0–40.0 Ka<br />
26.5–40.0 R<br />
30–300 GHz Extremely high<br />
frequency (EHF)<br />
Letter designation<br />
27.0–40.0 Ka<br />
26.5–40.0 R<br />
33.0–50.0 Q<br />
40.0–75.0 V<br />
75.0–110.0 W<br />
110–300 mm (millimeter)<br />
10 3 –10 7 GHz Infrared, visible<br />
light, and<br />
ultraviolet<br />
a kHz = 10 3 Hz; MHz = 10 6 Hz; GHz = 10 9 Hz.<br />
LOS propagation, cosmic<br />
noise<br />
LOS propagation; rainfall<br />
attenuation above<br />
10 GHz, atmospheric<br />
attenuation because of<br />
oxygen and water<br />
vapor, high water-vapor<br />
absorption at 22.2 GHz<br />
Same; high water-vapor<br />
absorption at 183 GHz<br />
and oxygen absorption<br />
at 60 and 119 GHz<br />
LOS propagation<br />
UHF television, cellular<br />
telephone, navigational<br />
aids, radar, GPS,<br />
microwave links, personal<br />
communication systems<br />
Satellite communication,<br />
radar microwave links<br />
Radar, satellite,<br />
experimental<br />
Optical communications<br />
For a detailed chart of current frequency allocations in the United States see<br />
http://www.ntica. doc.gov/osmhome/allochrt.html.<br />
1–8 PROPAGATION OF ELECTROMAGNETIC WAVES<br />
The propagation characteristics of electromagnetic waves used in wireless channels are<br />
highly dependent on the frequency. This situation is shown in Table 1–2, where users are<br />
assigned frequencies that have the appropriate propagation characteristics for the coverage<br />
needed. The propagation characteristics are the result of changes in the radio-wave velocity as
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