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  1. #1
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    Using 65 degree directional antenna instead of 120 degree one in CDMA

    whats purpose of using directional antenna of 65 degree in cdma instead of 120 degree?

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  2. #2
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    Re: directional antenna

    This reducing the angular size of the sectors allows more frequency reuse. This will work on all signals of any modulation type.



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    Re: directional antenna

    When hooked to a transmitter, a directional antenna will have apprent gain--in other words it will look like you are transmitting with a higher power than you actually are. It will increase the link range.

    When hooked to a receiver, a directional antenna will reject signals that are off-axis, reducing the amount of interference.



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  4. #4
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    Re: directional antenna

    A BTS ormally has 3 antennas for 3 sectors. Theoretically, Cell coverage is circular; thus it requires 3 antennas of beamwidth 120 deg. each to cover one cell.

    The problem is if we use the 120 deg antenna forall the sectors , practically the signal is also transmitted in sidelobes which overlaps the neighbouring sector/antenna's signal. In CDMA this creates an Co- Channel interfernce since CDMA has only one frequency i.e. universal freq reuse.

    If we use 65 deg beamwidth antenna , then the actual signal will be transmitted in ≈ 90-110°. This serves the purpose of covering 120° sector with minimum interference.

    Not only CDMA but every cellular system uses 65° beamwidth antenna to cover 120° sector. 120° beamwidth antennas are also available and used to cover 180 ° sector.



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    Re: directional antenna

    the less degrees of beam get more gain , and the transmitting power can
    be saved.



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  6. #6
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    directional antenna

    in some areas the coverage is not necessary 360
    degrees as in the case of unpopulated areas but
    requiring highways coverage, so 60 degrees antennas
    pointing in opposite direction will cover the highway.



  7. #7
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    Re: directional antenna

    This reducing the angular size of the sectors allows more frequency reuse. This will work on all signals of any modulation type.



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