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Which 4G Antenna for WiMax Sprint USB U1901? Will it help indoors?

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  • Which 4G Antenna for WiMax Sprint USB U1901? Will it help indoors?

    Hello,

    I have a sprint 4G U1901 and I'm getting a really bad connection: 2 bars, and download of about 8kbps and upload of about 2kbps on average. Sometimes I will get as much as 27kbps, but it usually only lasts a second or two. Dropped connection every few minutes.

    This is slower than my dial-up modem, and even loading the Yahoo.com homepage takes about 4-5 minutes.

    I live in the bottom floor of a condo and I can't put an antenna outside. Would it help my download speed or connection to get an antenna and keep it indoors?

    Which antenna should I get?

    Thanks!

  • #2
    How good is your outdoor signal? Whether this would work would depend on this. I understand you can't put an antenna outdoors but knowing how strong the signal is outdoors will give an idea as to whether an indoor mounted high gain antenna could help.

    If you don't even have a good outdoor signal then it is very unlikely that putting a high gain antennas indoors will help you. On the other hand, if you find that you have a very strong outdoor signal then it is likely that something like an 18dBi Panel antenna would help overcome the signal loss through the building. You can get this from this kit: http://www.rfwel.com/shop/4G-USB-Mod...tenna-Kit.html

    Of course if you already have a part of your condo (e.g near window) that has a good enough signal then adding an antenna here and running low loss cable to wherever you want to locate you modem would be an option.
    KF7RCQ

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    • #3
      I'm getting a pretty good signal outdoors (3 or 4 bars) just outside of my window. So, I will try the antenna.

      Will the 18dBi panel antenna work better than the 12dBi omni-directional antenna? I don't really know what direction to point the antenna, although I could just experiment with it.

      Do I need to buy two of these antennas? How much difference will it make compared to just one? Do I need the 10ft cable, if I'm just going to put the antenna right beside the USB stick modem?

      Thanks for your help!

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      • #4
        Will the 18dBi panel antenna work better than the 12dBi omni-directional antenna? I don't really know what direction to point the antenna, although I could just experiment with it.
        Yes the 18dBi directional is better than the 12dBi omni-directional in most cases. Yes you don't need to know in advance where to orient it and in fact many times even if you have an idea the actual direction that gives the best signal might be slightly different due to reflections. The best way is to sweep the orientation while observing the RSSI taking care to make sure that the signal is stable and not just a momentary peak.

        Do I need to buy two of these antennas? How much difference will it make compared to just one?
        Ideally yes but practically no. Most people get really good performance with just one. What most people do is get one and if they feel that their performance could be improved even more with a second antenna they get that later. Here is an article that goes more into the reasons: http://www.rfwel.com/forums/content....s-Two-Antennas


        Do I need the 10ft cable, if I'm just going to put the antenna right beside the USB stick modem?
        As a practical matter you do need some cable. The pigtail has only about a 10" cable so unless you are going to tape the modem (or wimax router which has the modem) literally to the back of the antenna you would need some cable to allow practical placement. You can select "no cable" in the kit above then probably get this 2ft jumper: http://www.rfwel.com/shop/2FT-N-Male...oss-Cable.html


        Incidentally, on taping the modem to the back of the antenna, don't do it!! Two bad things happen when you do this:
        • MIMO Antenna Correlation degrades MIMO diversity performance:- Even given the relatively high 30dB of Front-to-Back ratio available on the 18dBi antenna when you are attaching the modem to the back it means that the primary antenna signal and auxiliary antenna signal are highly correlated (the aux signal being 30dB weaker). MIMO works best when these signals are as uncorrelated as possible which is why we recommend separating the primary and secondary antennas as much as possible (or if you have the primary outdoors and don't hook up the secondary such that it still uses the internal antenna, this is picking up an indoor signal).
        • Receiver desensitization:- This is especially if you use a WiMax router or one of the CPE modems that has a WiFi radio as well. Desensitization simply means that either the WiMax radio of the WiFi radio is receiving a significantly strong signal from other than it's frequency (so the 2.4GHz WiFi radio is receiving strong interference from the 2.6GHz WiMax radio or viceversa).
        KF7RCQ

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