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  • New building dilemma

    Today I discovered that access to high speed business offerings from Comcast, Charter, etc. are not available at one of our new facilities. Apparently 2000 ft. of cable needs to be run in order to serve a rather large industrial park but none of the providers have taken the initiative as the cable must go beneath a set of railroad tracks.

    To that end we're going to start with Sprint 4G Wimax service, however, service appears to be somewhat weak in the area according to the Clear map (better detail than Sprint's map) below. The building is approximately 50x100 steel and concrete construction with a standing seam metal roof so I am anticipating signal issues.

    If external antenna(s) are installed, the cable distance will be roughly 100 feet. The nearest tower is 1.5 miles to the north and until I perform a survey from the roof I am unsure whether a clear LOS exists. This is a light industrial / office area near the airport with no buildings over 4-5 stories. There are 3 additional towers in the vicinity which are depicted in the second attachment below.

    Naturally, I'd prefer the installation of an outdoor rated 4G modem in a weatherproof enclosure to reduce cable losses, but it's my understanding that Sprint will not provision generic devices. In light of this, I'm looking for a recommendations on how to keep losses at a minimum, as I would like to avoid installing a parabolic or grid antenna for aesthetic reasons. I suppose an upgrade to LMR600 could help slightly, however, having almost no RF background I'm unsure of which cable/antenna configuration to pursue at this point.

    Any assistance or advice that may be provided will be greatly appreciated.



  • #2
    The building is approximately 50x100 steel and concrete construction with a standing seam metal roof so I am anticipating signal issues.
    Wow - Classical RF-shielding scenario. I concur you would very likey run into indoor penetration issues.

    If external antenna(s) are installed, the cable distance will be roughly 100 feet. The nearest tower is 1.5 miles to the north and until I perform a survey from the roof I am unsure whether a clear LOS exists. This is a light industrial / office area near the airport with no buildings over 4-5 stories. There are 3 additional towers in the vicinity which are depicted in the second attachment below.
    Applicability of an outdoor antenna will pretty much boil down to how strong your outdoor signal is. With LOS and choice of towers as close as 1.5miles away it is very likely you will find a strong outdoor signal. In this case 100ft is not far at all even with LMR400 cable (attenuates signal by 6.9dB/100ft at 2.6GHz). So if you used the 18dBi panel antenna available with the wimax antenna kit even with the cable loss plus connector and insertion losses of a lightning surge device (which all would contribute less than 1dB of loss) you would still have about 10dB of effective gain which is much more than the approximate 3dBi of the factory installed integrated printed antennas (recall dB is a logarithmic scale).

    You are right that LMR-600 cable would be better (at about 4.5dB/100ft at 2.6GHz) so your call would be if the extra 2.4dB of loss in going with LMR-400 justifies the additional cost of LMR-600. It could very well be justified depending on how strong your outdoor signal is and realizing that since dB is a logarithmic scale 2.4dB represents 42% of the power available with LMR600 loss (3dB difference would represent half the power lost).


    Naturally, I'd prefer the installation of an outdoor rated 4G modem in a weatherproof enclosure to reduce cable losses
    You could get something like this: http://www.rfwel.com/shop/HANA-SELEC...na-System.html which puts the Sprint/Clear certified modems in an outdoor ruggedized NEMA enclosure. You then need to run a single CAT5/6 cable from your network hub to the outdoor modem (router is POE-powered so don't need a separate power source & modems are powered by the router via USB port). This limits the data cable run to about 100m (~330ft). Use UV-shielded cable for outdoor run not inside a raceway/conduit.

    Since from the discussion above 100ft is not that big of a deal for LMR400/LMR600 signal (given a strong outdoor signal) placing the modem indoors and using outdoor antennas is preferred from a practical standpoint. One such problem related to using the outdoor enclosure above is that the modems are typically NOT designed for outdoor temperatures. Also by running individual cables to each MIMO antenna port in the modem it allows us to install higher gain antennas and better separate the primary and auxiliary antennas which improves MIMO performance. We do however find the outdoor NEMA enclosure solution as a viable option for some clients.
    KF7RCQ

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    • #3
      Thank you very much for the reply. I am just getting back to this project, I'll call your offices in a bit to discuss the matter a bit further and place an order.
      Last edited by thuor; 08-24-2011, 01:18 PM.

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      • #4
        I see that you have 3 separate numbers. Which is the best to call regarding this particular matter?
        Last edited by thuor; 08-24-2011, 01:18 PM.

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        • #5
          You could call +1.480.218.1877 and ask for tech support (i think option #4). It's better actually to use the contact-us form http://www.rfwel.com/contact.php indicating you want a callback the reason being since we are not really an online store (we are a wireless system integrator and licensed contractor) it might take a while for a technical person to get back to you on this which helps if its well routed via the contact us form.

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