EIRP(mW) : Tx(dBm) + Gain(dBi) – Loss(dB)
XdBm=10log(y/1mW)
1.An AP transmitter emits 40 mW of power through a cable that is "adding" 3 dB loss.
The Yagi antenna that is being used has 13.5 dBi gain. What is the EIRP?
10log40=16
16+13.5-3=26.5 dBm
2.An AP transmitter emits 20 mW of power through a cable that is "adding" 4 dB loss.
per 100 feet. The cable is 20 feet long. The omnidirectional antenna that is being
used is 5.2 dBi gain. What is the EIRP?
10log20=13.01
13.01+5.2-4/5=17.4dBm
3.An Ap transmitter emits 100 mW of power to an antenna directly connected to it.
The antenna that is being used is an 8.5 dBi patch antenna. What is the EIRP?
10log100=20
20+8.5=28.5dBm
4.you have been asked not to exceed 20 dBm EIRP on a 3.0 dBi omnidirectional
antenna. Which power level should you set your AP to knowing that you use 50 feet
of 6 dB/100 feet loss cable?
20dBM=Tx+3dBi-3dB
5.you have been asked not to exceed 17 dBm EIRP on a 13.5 dBi Yagi antenna.
Which power level should you set your AP to knowing that you will use 150 feet of
6 dB/100 feet loss cable and that the cable connectors add an extra 0.5 dB loss?
17=Tx+13.5-9-0.5
Tx=13
6.You have been asked not to exceed 17 dBm EIRP on a 5.2 patch antenna . How
much length of 2.8 dB loss per 100 feet cable should you use,knowing that th Ap
power level is statically set to 40 mW?
17dBm=40mW/16dBm+52dBi-loss
loss=4.2
4.2/2.8*100=150feet