• By Tony-T - edited: October 18, 2020


    I'd like to know the consensus on where the TX power 6dB offset 'rule' between 2.4GHz and 5GHz should be applied......


    Should the 6dB off set between 2.4GHz and 5GHz, be designed for "in the air" (EIRP values) - as that is what the client device will be experiencing?


    (And antennas often have different gain values for 2.4GHz and 5GHz - which would skew the offset, if set at TX out)


    Thoughts please


  • By Howard - edited: October 29, 2020

    Can you explain what YOU mean by the 6dB "rule".    It's not clear.

    Do you mean the fact that dual mode antennas are"designed" to have higher gain in the 5 GHz range ?    Although that is generally true, the difference is never that great.

    Good PA's, power amplifiers, especially at higher frequencies are expensive. 6 dB is a very large difference from a PA perspective.

    Newer 802.11n/ac radios are also configured with LOWER output, than were older installations. and because the FCC mandated that multi-stream radios must produce LESS power per stream.

  • Hello Howard

    Thankyou for the reply, apologies for my delayed response, been busy

    6dB 'rule':

    As stated by Keith Parsons (and others) - 2.4GHz Tx power being 6dB lower than 5GHz Tx power, will provide similar coverage area for both frequency bands. (this is the 'standard' starting point of the company I work for)

    Should this 6dB difference between 2.4GHz and 5GHz be applied at Tx out (before antenna) or at EIRP (after antenna)?

    Antenna gain can be the same for both bands or can be different (very true Howard) - depending on the antenna. The most different that I am aware of is the Cisco AIR-ANT-2547 omni - 3dB different.

    Any difference in antenna gain would skew the desired 6dB difference between 2.4GHz and 5GHz - if applied at Tx out.


    And if I may please - a new more general question  (related to the above discussion)

    When talking about AP Tx power, should the power output setting of the AP, reference the Tx output (before antenna) or EIRP (after antenna)?



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