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Clear USB Modem Antenna

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  • Clear USB Modem Antenna

    I am using the Clearwire 4G broadband system with a Motorola USB 100 Wave 2 Ready USB modum in Salem Oregon. I find the signal strength, inside brick or metal roofed homes I visit, is below the minimum for the modum. The homes are within the Clear service footprint and I can obtain signal inside my car parked in the homes driveway.

    I would like to know if your universal coupled atenna (SKU indcadptr #1815) and either the Freedom Blade (SKU #1288) or the Freedom Antenna (SKU #1192) is a proper remedy for my problem. I am unable to find how the antenna is powered and by what means.

  • #2
    The freedom antennas were originally designed and spec'd for 2.4GHz ISM (WiFi) frequency band. We have seen them used for 2.5-2.7GHz WiMax but not sure what the spec's are in this frequency band specifically what the antenna gain is. Usually passive antennas by their nature have wideband characteristics so can work at a wide range of frequencies but usually by design they are tuned to a center frequency (i.e maximum gain, minimum reverse isolation at a specified frequency).

    We have a kit for this USB modem and a high gain directional outdoor antenna here: http://www.rfwel.com/shop/?target=pr...roduct_id=1838 (this can be mounted indoors as well although it's not very aesthetic). We also have other different antennas spec'd for the 2.5GHz hand here: http://www.rfwel.com/4g-data/wimax-a...wimax_antennas

    To hook the universal coupler to any antenna only thing is to realize the coupler is FME-Male. If you need anything more than about 10ft a good low loss cable is the LMR400 series cables. These are typically N-Male. So to hook up the coupler to the cable you can use an N-Female/FME-female connector.

    Just to answer your specific question on how these antennas are powered: These antennas (and indeed most antennas you run into for wireless radios/modems) are passive meaning they don't need a separate power connector - they are driven directly by the modem.

    One other very important point to note is the antenna gain. Notice that the antennas you point out below have a gain of 3dBi and the directional antenna in the kit above is 16dBi. This is a HUGE difference if you realize that dBi is a logarithmic scale - 10xLog(Gain)! You need such high gain to overcome cables losses if you will be mounting this antenna outdoor far from where the modem would reside.

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    • #3
      Question

      So the antenna kit connects to the USB modem? I am confused, I have done my homework on the topic but I am confused how this antenna actually interfaces with the USB dongle, does it plug in somewhere or simply by attaching one end to the usb dongle does it get the signal. Could you please clarify?

      Thanks,

      Ryan

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      • #4
        Since the USB modem does not have an external antenna port this interfaces by coupling the internal antenna to the surfaces of the coupler which is velcro'd to it. This is typically not the most ideal method to attach an external antenna due to losses arising from imperfect coupling but it works great especially if your received signal strength is not too weak to start with. As we have discusses in previous posts another non-ideality of this method is that one is not able to obtain the benefits of MIMO multiantenna diversity as you would with say the Zyxel modem that has two external antenna ports.
        KF7RCQ

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        • #5
          Sprint U300 U301 ARCPA2516B01 Coupling Not Working

          I have 2 Bars on Sprint WIMAX Network using the U301 and no bars using the U300. I purchased the ARCPA2516B01 that is supposed to provide up to 16Db gain a 10 foot cable and a coupler to velcro to my USB aircard.
          This is the signal I am getting on the USB U301 without any antennae

          Rx Power -77
          CINR 9
          Tx Power 22

          I have the panel against the window and When I attach the coupler to the U301 usb aircard this is the signal I am getting
          Rx Power -81
          CINR 5
          Tx Power 23
          http://www.speedtest.net/result/684554716.png

          The download speed decreases a lot with the antennae attached. Sometime the signal completely drops with the antennae attached. Can you help me to get this to improve my gain?

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          • #6
            Do you still have this problem? What are the pre- and post- results RSS and CINR results with the U300? Even considering coupler losses and cable losses we would not expect such a degradation in received signal level unless you the loss in MIMO diversity gain is this drastic - would like to see results with different orientation or different location to rule out location dependent RF propagation multipath effects.

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