Extension cable for Wi-Fi antennas ?

Discussion in 'Cisco' started by JF Mezei, Oct 28, 2009.

  1. JF Mezei

    JF Mezei Guest

    I have a 871W router. The 2 antennas are in the back of the unit.

    I would like to put the unit in a rack. Would making cables (about 1 or
    2metres (3 to 6 feet) to relocate the antennas to the top of the rack
    work or would that significantly reduce the power/sensitivity of antennas ?

    What type of coax cable would be needed ?
    JF Mezei, Oct 28, 2009
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  2. I don't think moving the stock rubber-ducky antennas are going to do
    much for range or sensativity. But the reason they are on connectors
    is so that you can use your own antennas if you wish.

    You can buy many different higher-gain WiFi antennas, all would come
    with the proper RP-TNC connectors on them (otherwise, the answer to
    your last question is an RP-TNC extension cable).

    But if you are worried about range and sensitivity, I'd just go ahead
    and swap the rubber-duckys out with something external with a bit more
    gain anyway.

    Cisco has a huge range they (re)sell...


    But other brands/sources can be cheaper.

    Just be careful of connector type, alot of the lower end consumer
    stuff switched to a smaller connector (RP-SMA), cisco stuck with the
    standard RP-TNC, although some bigger/outdoor antennas may have N, but
    cables that go from N to RP-TNC are readily available. (confused yet?)
    Doug McIntyre, Oct 28, 2009
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  3. JF Mezei

    Uli Link Guest

    Depends on quality of connectors and cable.
    2 meters incl. 2 additional connectors RP-TNC male/female will result in
    more than 2dB loss. This may be overcompensated by the better
    positioning of the antennas. The cable loss can be significantly higher.
    Rule of thumb: the thinner and more flexible the cable is, the higher
    the loss per length.
    Flexible low loss cable is quite expensive in small quantities.
    I strongly recommends buying ready to use cables from professional dealers.
    You cannot use your soldering iron. The cable must fit physically into
    the connector for matching the impedance.
    Your signal uses 2.4 GHz not DC, forget about such things for 5GHz
    802.11a radios.

    I would place the 870 just on top of the rack as it is no 19" rack unit.
    Uli Link, Oct 28, 2009
  4. JF Mezei

    Rob Guest

    Remember that gain in antennas is always achieved by directivity.

    An antenna with higher gain always has more directivity. When the
    purpose of the WiFi router is to provide wireless access inside a
    building, this may not be what you want. With a suitable pattern
    it could be usable for access from a single floor, but that is about it.

    Antennas with gain are mainly suitable for point-to-point links.
    Rob, Oct 28, 2009
  5. JF Mezei

    Uli Link Guest

    There are omni directional antennas with 7dB or more gain.

    Those direct vertically, but horizontally 360°. Usually an ideal
    solution for a single floor.
    Uli Link, Oct 28, 2009
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