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Tilt and Height

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  • #53333 Reply
    MKT
    Guest

    Hi !

    Which one is better option and why for achieving a good indoor coverage:-

    1. Height of Antenna = More
    Tilt of Antenna= More

    2. Height of Antenna = less
    Tilt of Antenna= less

    Regards

    #53334 Reply
    pix
    Guest

    high antenna with more tilt –> the antenna will shoot above the surrounding obstacles, so all buildings within the best server area are going to receive equal indoor coverage.

    if you put you antenna too low, only the nearby buildings will have good coverage.

    #53335 Reply
    MKT
    Guest

    So…

    what is fun in having a antenna installed at lower heights?

    If tilt can keep the size of cell small as well as can provide a good indoor coverage then…

    don’t you think we should make a thumb rule in RF planning to keep the antenna height more?

    or

    the practice of lower antenna heights by RF planner is just to cater the sales need of his employer !!!

    Fact behind the thought:-

    A city with 10 BTS just a few years back….having average height of antenna/BTS site at 40 m from ground.

    Now,

    There are 30 BTS in the same city…subscribers have grown manifold ….And the height of antenna’s have came down to 24-25 M on an average…

    They have added capacity, no doubt..but

    Indoor coverage has been affected badly in almost all the dense clutters..

    can’t they have added the capacity by planning the 30 BTS sites with an antenna height of 40 m and tilt of 6 degrees to 8 degrees???

    This could have probably saved a big churn of subscribers due to poor indoor coverage!!!!!!!

    Regards

    #53336 Reply
    MKT
    Guest

    If the effective tilt of antenna is calculated as

    Effective tilt= Electrical tilt + Mechanical tilt

    And electrical tilt has the range from 0 to 8 degree then,

    Isn’t it will be a wise to give preference to electrical tilt for all your requirements of tilt ranging from 0 to 8 degrees, as the same has ease in implementing. I mean just a turning of knob will do it as compared to the loosening and fighting of mechanical fixtures/nuts/bolts for the mechanical one.

    regards

    MKT

    #53337 Reply
    pix
    Guest

    mkt,

    high antennas in the cities are difficult to get, and whichever tilt you put, there will always be reflections the cell coverage won’t be as contained as you’d need.

    And putting less sites mean you’re gonna put a lot of TRX per site (3×8, 3×12 ?) The frequency planning is going to be a pure mess.

    electrical tilt is favored over mechanical tilt, always. The electrical tilt can range from 0° to 14°, even more.

    #53338 Reply
    MKT
    Guest

    Thanks

    But

    What is the need for such a large range for tilts,

    i mean 0 to 14 for electrical plus mechanical. I think it is too much.

    Also,

    What purpose we are going to solve with tilts of 10 degree or more:-

    Regards

    #53339 Reply
    pix
    Guest

    mkt,

    in very dense areas, a tilt of 10° is quite common.

    so a possible tilt of 14° is not “extraordinary”. It could be used for very high sites also (imagine a site on a mountain, 1000m high, and the city at the bottom. Such a tilt could be useful). I can see some uses in hilly areas as well.

    Anyway, it’s always good to give the choice. The more the better, isn’t it ?

    Plus, it’s interesting to put a high electric downtilt an a bit of mechanical uptilt. That solution reduces the backlobe the most.

    #53340 Reply
    Bilal
    Guest

    UL interference is usually a matter of concern when antennas are too high. Because MS antennas are not directional and of course you can’t tilt them 🙂 So higher the BTS antenna, more interference it will capture.

    #53341 Reply
    pix
    Guest

    bilal,

    i never thought about it this way. however, the antenna is quite directive, and it will tend to increase signals from the main lobe, while attenuate signals from other directions.
    I mean the UL and the DL will be equally hard to manage with a high site.

    #53342 Reply
    Bilal
    Guest

    Agreed 🙂

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