output power of antenna

Could anyone tell me the output power of the antenna, in other words , the input power of LNA that follows the antenna in 802.11b systems.

Thanks!

hellotxn said:

Could anyone tell me the output power of the antenna, in other words , the input power of LNA that follows the antenna in 802.11b systems.

Thanks!

Click to expand...

I don't think that I understand your question. Antenna has no output power, it has gain.

sinip said:

I don't think that I understand your question. Antenna has no output power, it has gain.

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How ? sure Antenna has o/p power which is the power in its radiation resistance and that power control how long distance will the signal travel in the medium ! ! !

sorry, I am not familiar with the concept about rf system. I wish to design an amplifier in radio over fiber link.The input of the amplifer is the signal from the antenna, and the output of the amplifier is to the laser. I wish to estimate the range of the signal intensity in a practial 802.11system on fiber, I think it is helpfule for me to design the circuit.Could anyone give me some guide?

The ouput you receive out the antenna will be
variable, can go from -75/-85/-95 dBm up to
0/10/20 dBm. The output depends on the link(distance),
if you have the antenna close to the access point
then the energy collected is big.

I think will be very difficult to complain with this because the amplitude of the RF signal is very variable depending on the RF field surronding the antenna, instead you have not a so wide dynamic range on the laser modulation.
Even trying with a log detector it will not modify the situation because the frequency and phase informations will be lost.
The only way is to decode the incoming signal and THEN modulate the laser with the data.

Mandi

FANT said:

The only way is to decode the incoming signal and THEN modulate the laser with the data.

Mandi

Click to expand...

Exactly.

Added after 5 minutes:

Abu Ammora said:

sinip said:

I don't think that I understand your question. Antenna has no output power, it has gain.

Click to expand...

How ? sure Antenna has o/p power which is the power in its radiation resistance and that power control how long distance will the signal travel in the medium ! ! !

Click to expand...

Antenna is passive element, therefore it has no output power "per se". It just radiates whatewer power you feed in. However, two things should be considered.
1. How much power you can feed into an antenna before causing physical damage to it due to heating or flashover caused by high voltage.
2. How big gain (in dB) antenna has. The bigger the gain the longer the distance that the signal can reach, but more directive it gets.