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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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Real Impact of 10' LMR-195 Antenna Extension Cable

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  • 1.  Real Impact of 10' LMR-195 Antenna Extension Cable

    Posted Aug 05, 2022 01:21 PM
    If I add a 10' extension of low-loss LMR-195 (loss of ~3 dB) between an Aruba AP-ANT-48 panel antenna (8.5 dBi gain at 5 GHz) and an AP-534 at 5 GHz set for 802.11ax HE20 and be able to achieve MCS11? What performance degradation am I likely to realistically see with the ~3 dB (half signal strength) of additional loss by the extension cable? According to the AP spec sheet, the AP receiver sensitivity is -60 dBm per each of the x4 receive chains.

    Thanks,
    Brad


  • 2.  RE: Real Impact of 10' LMR-195 Antenna Extension Cable

    EMPLOYEE
    Posted Aug 17, 2022 05:08 AM
    That depends on where the client is; and in which direction you are asking the question. External antenna's should be avoided, unless absolutely necessary (additional mounting, cost, points of failure). Extension cables should even more be avoided.

    You can ask your Aruba partner, or a specialist in WiFi/RF design to calculate the link budget in both directions and make an estimate of the performance (degradation), but more important create a design that matches your requirements. The transmit power from the AP to the client will be compensated if you enter the antenna system gain of 5.5dBi, so I would not expect too much degradation on the rates to the client.

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    Herman Robers
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    If you have urgent issues, always contact your Aruba partner, distributor, or Aruba TAC Support. Check https://www.arubanetworks.com/support-services/contact-support/ for how to contact Aruba TAC. Any opinions expressed here are solely my own and not necessarily that of Hewlett Packard Enterprise or Aruba Networks.

    In case your problem is solved, please invest the time to post a follow-up with the information on how you solved it. Others can benefit from that.
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  • 3.  RE: Real Impact of 10' LMR-195 Antenna Extension Cable

    EMPLOYEE
    Posted Aug 17, 2022 04:55 PM
    It will simply reduce the effective antenna gain by 3dB. Assuming the client is in the direction of the antenna beam, the signal from that client will experience a receive antenna gain of 5.5dBi at the AP. The 4 receive chains will add another 6dB of MIMO (MRC) gain, so as long as the signal gets to the AP at -71.5dBm or better, MCS11 should be achievable.
    On the transmit side, the AP will typically simply transmit a bit more power (assuming it's not maxed out) to compensate for this cable loss, assuming it is properly accounted for in the provisioned antenna gain number. Since all transmit power levels (set or reported) are in terms of EIRP power (which includes antenna gain), programming a lower gain value will result in the software tuning the radio to a higher conducted power level (to hit the same EIRP).