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Occasional Contributor I
Posts: 6
Registered: ‎03-01-2012

Question about AP's maximum EIRP

 

Hello,

I have a few AP-124s installed with AP-ANT-17 and they are provisioned with the relevant antenna gains according to specs: 6 for g, 5 for a. Although the arm profile is set to the max transmit power (127), the APs do not go higher than 21 dBm in the a band. Below you can find the result of the driver-log command for one AP. It is also weird that the gain is set to 4, although provisioned to be 5..

180    113510.891656 wifi0: EIRP (Config: 21.0dBm, Set: 21.0dBm, AP Max: 21.0dBm, Reg Max: 30dBm), Conducted Power Set: 17.0dBm, Gain: 4.0dBm

The same thing occurs with another installation including AP-124s and AP-ANT-16. On the other hand, when I am dealing with AP-105 (internal antennas), the max EIRP can go up to 23 or 24 dBm depending on the channel, which is the AP’s maximum according to the specifications.

Can someone help me understand what is the issue with external antennas and max transmit power?

 

Many Thanks

 

Guru Elite
Posts: 21,279
Registered: ‎03-29-2007

Re: Question about AP's maximum EIRP

Please try the article here:  https://arubanetworkskb.secure.force.com/pkb/articles/HowTo/R-13

 

 



Colin Joseph
Aruba Customer Engineering

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Aruba
Posts: 224
Registered: ‎04-27-2009

Re: Question about AP's maximum EIRP

Here's what happens:

- The maximum conducted transmit power in 5GHz on an AP-124 is 17dBm (per chain)

- The applicable regulatory limit for the AP-124 when configured for operation in the US, is 30dBm in the U-NII-2 and U-NII-2e bands

- Because the AP-124 combines (diplexes) signals from both bands (2.4GHz and 5GHz) on a single set of connectors, there's some additional loss between the radio and external connectors. In 5GHz, that's 1dB

- The way the software reports this loss is by adjusting the provisioned antenna gain, so the remianing gain is 4dBi

- Resulting EIRP is 17 + 5 - 1 = 21dBm

- The AP-105 has significantly more transmit power available than the AP-12x

/Onno
Aruba
Posts: 224
Registered: ‎04-27-2009

Re: Question about AP's maximum EIRP

BTW, the per chain max conducted transmit power levels are specified in the AP datasheets

/Onno
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