Rf Terms And Definitions; Figure 9-7. Attenuation Of An Rf Signal - Alvarion BreezeNET PRO.11 Series User Manual

Appendix

9.4.2 RF Terms and Definitions

The dB convention is an abbreviation for decibels. It shows the relationship
between two values.
RF power level at either the transmitter output or the receiver input is expressed in
Watts. It can also be expressed in dBm. The relation between dBm and Watts can
be expressed as follows:
P = 10 x Log P
dBm
For example: 1 Watt = 1000 mW; P
For link budget calculations, the dBm convention is more convenient than the Watts
convention.
Attenuation (fading) of an RF signal is defined as follows:
P is the incident power level at the attenuated input
in
P is the output power level at the attenuated output
out
Attenuation is expressed in dB as follows: P
For example: If, due to attenuation, half the power is lost (P
attenuation in dB is -10 x Log (1/2) = 3
User's Guide
mw
100 mW; P = 10 x Log 100 = 20 dBm
dBm

Figure 9-7. Attenuation of an RF signal

= 10 x Log 1000 = 30 dBm
dBm
= -10 x Log (P
dB
dB
9-18
/P )
out in
/P = 1/2),
out in
BreezeNET PRO.11 Series