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Access network design for branch, remote, outdoor and campus locations with Aruba access points, and mobility controllers.
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Max antenna gain - IAP-104 and 204

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  • 1.  Max antenna gain - IAP-104 and 204

    Posted Aug 05, 2015 10:59 AM

    Hello,  colleagues!

    What reccomended maximum antenna gain for IAP-104 and IAP-204?


    In our tests - antennas with gain 3dBi (2,4GHz) work more better then antennas with gain 17dB.


    Thank you!

  • 2.  RE: Max antenna gain - IAP-104 and 204

    Posted Aug 05, 2015 11:05 AM

    Some correction:


    Table 2: Antenna Types and Maximum Antenna GainsGain (dBi)

    Frequency Band


    2.4 GHz




    5 GHz





    Question - can I connect to IAP omni-antenna with gain more then 6dBi?

    Because manually I can type gain more then 6 in config.


    Thank you!

  • 3.  RE: Max antenna gain - IAP-104 and 204

    Posted Aug 05, 2015 01:45 PM

    You are supposed to plug in the value of the actual antennas used on the AP into the 'antenna gain' variable in the provisioning screen. Setting higher values (say 17dBi) on a lower ACTUAL antenna gain of say 5dBi will result in much less power being driven from the radio.


    TL;DR, plug the actual antenna gain value into the fields on the provisioning page.

  • 4.  RE: Max antenna gain - IAP-104 and 204

    Posted Aug 06, 2015 01:44 AM

    Thank you for answer!



    I whant to know what is maximum antenna gain is normally working with IAP in practice?

    Because - now we testing and see that antenna with 17dBi gain is showing worse coverage area then antenna with 3dBi gain. And this is strange.

  • 5.  RE: Max antenna gain - IAP-104 and 204
    Best Answer

    Posted Aug 06, 2015 09:49 AM

    What I am saying is, and what is the proper thing to do, is that you (the installer or admin) have to put the actual antenna gain value (in dBi) into the provisioning field for that specific AP. It's not a variable value that you pick based on whether you want more coverage. If you are using a 3dBi antenna, then you put 3dBi into the fields. If you are using a 10dBi antenna, you put 10dBi into that field, etc. 

    The reason you see coverage dropping is because you are telling the AP that you have a higher gain antenna than you actually have. As a result, the AP is dropping the radio power output to stay within the configured Max EIRP or to stay within the regulatory EIRP limits. 

    Here's an example. Say you have an IAP-104 and you have four ANT_1B antennas connected to it (~4dBi @ 2.4Ghz and ~6dBi @ 5GHz). Lets say you then set the max EIRP in the radio config to 20dB on each radio. 

    So when you enter the proper antnena values into the provisioning field, you have the following:

    Radio Band--------RadioChipPower------AntennaGain----Overall EIRP

    2.4GHz radio @ 16dBm(20db-4dBi) + 4dBi antenna = 20dB EIRP

    5GHz radio @ 14dBm(20dB-6dBi) + 6dBi antennas = 20dB EIRP


    Coverage is good, because the radio is configured with the appropriate antenna gain values. Now, what happens when you use the SAME antenna but incorrectly configure 17dBi for the antnna gain. In this case, you tell the radios you are using a 17dBi antenna, and so they adjust their power WAY down so as not to exceed the 20dBm max EIRP limit. However, you don't actually have that antenna on there, and as a result, the effective EIRP is way too low, and you see a loss of coverage. 

    Radio Band------RadioChipPower------AntennaGain----Overall EIRP

    2.4GHz radio @ 3dBm(20-17dBi) + 4dBi antenna = 7dB EIRP

    5GHz radio @ 3dBm(20-17dBi + 6dBi antennas = 9dB EIRP

    So there is no effective 'maximum' ceiling, because the antenna gain is NOT used to add or substract coverage. The antenna gain values should match what antennas are actually being used. The reason you see a bigger drop when you select a larger antenna gain is because the radios are dropping the power to stay within the radio config or max EIRP regulatory limits because it thinks it has a 17dBi antenna connected to it, when in fact it's something much much lower. 


    TL;DR, actual antenna gain values provisioned MUST match the values of the antennas being used for the radios to work properly.

  • 6.  RE: Max antenna gain - IAP-104 and 204

    Posted Aug 06, 2015 09:52 AM

    If you are using an ACTUAL 17dBi antenna, it's not one that Aruba manufactures, so we cannot speak to it's performance. But you would need to provide the actual make of the antennas (model with data sheet), as well as outline the trace of all the connectors, jumpers, LMR extensions, etc used. Most higher gain antennas used outdoor N-type connectors and the IAP-104 has RP-SMA, so if you are using jumpers to interconnect the RP-SMA to N connector, you have additional loss. If you are using long LMR cables to connect the antenna to the AP some distance away, that also will add loss. If the antenna is not MIMO-rated, it will perform terribly


    So if you are saying in your second post you are using an ACTUAL 17dBi antenna, we would need far more explicit details as to what that is, how it's connected, and how you are measuring 'coverage'. 

  • 7.  RE: Max antenna gain - IAP-104 and 204

    Posted Aug 10, 2015 11:12 AM

    Thank you for reply!


    I take orginal Aruba's antenna - AP-ANT-19 (3dBi/6dBi).

    Type regulatory domain - Singapure.

    RF -> ARM -> Min and Max transmit power -> "Max"

    Antenna gain 3dBi (5GHz put in Monitor mode - I need only 2,4GHz)


    Try with 2 programs:

    - InSSIDer - in lap-top

    - Wifi Analizer - in Android phone


    Have situation that in distance 5 meters from IAP-204 I have signal -65...-60dBm (it's not so good in this distance).

    I have other-vendor AP's in other room and their signal some times is better then signal from IAP-204 in this room.


    What I can configure to do more better signal strength?

  • 8.  RE: Max antenna gain - IAP-104 and 204

    Posted Aug 10, 2015 12:54 PM

    What other vendor and antenna? Hard to compare two different vendors when their readio caharcteristics might be different, different antenna gains and antenna shapes, etc. Also, ANT-19s are NOT MIMO-based antennas, so they will not provide ideal wifi coverage with the 204 unless you are manually decorrelating (manually polarizing) them since your testing distance is pretty short. 

  • 9.  RE: Max antenna gain - IAP-104 and 204

    Posted Sep 08, 2015 09:54 AM
      |   view attached


    I was just going through these posts, I have similar issue but I am at desigining phase

    I am trying to design a Wireless Network for office the walls of office is very thick and customer tried Access points having 6dBi Antenna on 5Ghz but coverage is not sufficent now customer is looking for Aruba Access Points with High gain antennas, we suggested to go with IAP 215 3x3 MIMO which has 4 integrated antennas of 5dBi on 5Ghz band but customer wants high gain antenna for better coverage can you please suggest





  • 10.  RE: Max antenna gain - IAP-104 and 204

    Posted Sep 09, 2015 11:19 AM

    The highest gain antenna for the 215 is the ANT-38 which is a 7.5dBi 60-deg antenna. However, it's likely not going to do what you need it to either, esp if the attenuation of the wall is the same or greater than the power output of the clients being used. Additionally, based on your map, your hallway will be saturated with ACI and CCI which will decrease the ability of the AP to hear the clients at such a low threshold.


    Going to higher gain is likely not going to offer any additional benefits and may exacerbate the problem in the hall.