High Gain AP's Ant.

[n.poongsawad]

Please help clarify this wording of Cisco's doc. I read through but still NOT clear what's that mean.

Wording of

A high-gain antenna on an access point will receive a signal from a 5-mW client from a greater distance than a low-gain antenna. It is the difference in transmitter power and receiver sensitivity that matters because the gain of an antenna is reciprocal.

Does those mean using HIGH-GAIN ant. at AP will help MORE coverage distance cover?

Thank in advance,

Nipat.p

[Scott Fella · Accepted solution]

The higher the gain, the more the signal is radiated. So here is the thing. Will a higher gain increase coverage... Sure it will, but the AP signal will travel further than a client which has a low gain antenna. There is something called EIRP, which in a nutshell is the antenna gain plus the transmit power. Typically you want to match the EIRP for AP and client so there isn't a one way communication. There is a saying about this... It's like a father and son throwing a ball. The father (high gain) can throw the ball at greater distance, but the son (low gain) will not be able to throw the ball to the father.

Hope that makes sense:)

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[n.poongsawad]

Hi Scott,

It's seem so cool you explanation, Dad & Son. All you said is what I used to ask you . Till I found this Cisco's document.

But there is another one boubt left, from wording of 'reciprocal'

Could AP /w  high gain ant be able 'Amplify' small signal from a client?

As they saying A high-gain antenna on an access point will receive a signal from a 5-mW client from a greater distance than a low-gain antenna.

Please help,

Nipat.p

[Scott Fella]

Yes a higher gain will hear signal better from a higher gain antenna, but it's doesn't mean the signal is better. What you have found is just stating that is may hear a client better. High gain has a more directed RF. Sonic your AP is 40' high and you have a high gain antenna, you clients on the ground will not hear the AP as well as if the AP had a low gain AP. Another analogy is a low gain AP is like a ball, now the higher the gain, swish the ball now and it's more like an oval. In my experience, the best way to increase coverage is to add access points. High gain might give you a little more coverage since the AP's EIRP is higher, but that doesn't mean the signal and nsr is what you want.

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[Scott Fella · Accepted solution]

Let me just add to your statement:

Could AP /w high gain ant be able 'Amplify' small signal from a client?

The answer is no... Amplify happens from the transmitter, so your client you'd have to amplify its signal as the AP does not amplify a clients signal.

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