Generic selectors
Exact matches only
Search in title
Search in content
Post Type Selectors

Space diversity

Viewing 10 posts - 1 through 10 (of 10 total)
  • Author
    Posts
  • 29th November 2007 at 17:47 #49906
    HuNi
    Guest

    Hi

    Can anyone please explain me how to calculate the distance between two antennas if I am using space diversity.

    Regards
    HuNi

    29th November 2007 at 18:30 #49907
    pix
    Guest

    there is a formula for that… but it’s totally empirical. Better than the formula is to follow the recommendations, based on experiments :

    For GSM900 : at least 3m horizontal separation
    For DCS1800 : at least 1.5m horizontal separation

    Additional rule : if height of antenna > 10*3m (or 10*1.5m for DCS1800), then the separation should not be equal to the values above, but should be at least equal to Height/10.

    If you’re using vertical separation, then the distances are shorter but it is slightly less effective.

    Pix

    30th November 2007 at 06:27 #49908
    HuNi
    Guest

    Thank you Pix

    30th November 2007 at 10:14 #49909
    emreigrek
    Guest

    i never forget you pix. God bless you 🙂

    3rd December 2007 at 04:29 #49910
    RK
    Guest

    The recommendation in general is 10x wavelength to 20x wavelngth. Of course, the higher separation the better since you’re able to de-couple the signals on both RX branches better. In GSM 1800 and PCS 1900 we’ve used 3 meter separation in deployments. But these days dual pol antenna is the answer for diversity.

    RK

    3rd December 2007 at 11:57 #49911
    Pix
    Guest

    Hello RK,

    when you say dual polar, you mean dualband cross-polar antennas ?

    Do you use this crosspolars in rural areas as well ?

    4th December 2007 at 05:05 #49912
    RK
    Guest

    Dual Pol = Cross polar antenna. BTW, quad pol antennas are also available in the market these days. I am talking here about mature markets like Europe and North America. In some cases (even if it is rural environment) more antennas sticking out of the buildingds are not preferred due to aesthetics. So dual pol antennas rule. But yes, these are about 1 dB inferior due to lower signal de-correlation achievable.

    RK

    4th December 2007 at 20:32 #49913
    Pix
    Guest

    RK, thanks for the input 🙂

    I never heard about the quad pol, it’s not in the catalog of the main antenna vendors..

    i’m very curious, does it have 4 different polarizations ? (0°, 45°, 90°, 135° ?)

    5th December 2007 at 02:46 #49914
    RK
    Guest

    That is correct Pix, it is 0°, 45°, 90°, 135°. Not really sure what the applications are in 2G and 3G network- maybe applicable for 4-way diversity (?) that many vendors these days offer. I am almost sure Andrew has these antennas.

    Also, I think these antennas could be used in 4G technologies like WiMAX for 4×2 MIMO where TX at the Base station transmits on 4 parallel paths. Its also true that 4G will extensively use “smart antennas” which is an add-on smart functionality over X-pol antennas.

    RK

    5th December 2007 at 08:34 #49915
    Pix
    Guest

    Hello RK,

    I cannot find these antennas in Andrews catalog, Kathrein catalog or RFS catalog… what I can find is dual-dual polar antennas (called also “quad” antennas in Andrews), which are actually two dual polar antennas, side by side, within the same radome.

    These two antennas have the same polarization and the same frequency band. I guess they provide two crosspolar with a little bit of space diversity… so it can be used for 4RX/2TX DIV. But IMO i’d use that to avoid combining 4 TRX onto one Xpol antenna. I could transmit 2 TRX on one antenna, and 2 TRX on the other antenna, that avoid a loss of 3 to 4 dB.

    What do you think ?

    pix

  • Author
    Posts
Viewing 10 posts - 1 through 10 (of 10 total)
  • The forum ‘Telecom Design’ is closed to new topics and replies.