1. RADIO PHYSICS
5
SI symbols atto
10−18
1/1000000000000000000
a
femto
10−15
1/1000000000000000
f
pico
10−12
1/1000000000000
p
nano
10−9
1/1000000000
n
micro
10−6
1/1000000
µ
milli
10−3
1/1000
m
centi
10−2
1/100
c
kilo
10 3
1000
k
mega
10 6
1000000
M
giga
10 9
1000000000
G
tera
10 12
1000000000000
T
peta
10 15
1000000000000000
P
exa
10 18
1000000000000000000
E
Knowing the speed of light, we can calculate the wavelength for a given frequency. Let us take the example of the frequency of 802.11b wireless networking, which is: f = 2.4 GHz = 2,400,000,000 cycles / second wavelength (λ) = c / f = 3*108 / 2.4*109 = 1.25*10-1 m = 12.5 cm Frequency and therefore wavelength determine most of an electromagnetic wave’s behaviour. It governs the dimensions of the antennas that we build as well as the effect of the interactions with objects that are in the propagation path, including the biological effects in living beings. Wireless standards of course are distinguished by more than just the frequency they are working at - for example, 802.11b, 802.11g, 802.11n and 802.16 can all work at 2.4 GHz -, yet they are very different from one another.
