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omar_1966
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Posts: 21
Joined: Mon Oct 01, 2007 7:00 pm

### SECTORIAL ANTENNA

I HAVE A SECTORIAL ANTENNA IN A 80 FEET TOWER I HAVE CLIENTS FROM .5 TO 5 KM

HOW DO I KNOW THE ANTENNA TILT THAT I NEED TO USE, OR SHOULD I PUT THE ANTENNA WITH NO INCLINATION AT ALL???

doush
Long time Member
Posts: 627
Joined: Thu Jun 04, 2009 3:11 pm

### Re: SECTORIAL ANTENNA

my sectors are 30m high and i didint give any tilt. works fine

omar_1966
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Posts: 21
Joined: Mon Oct 01, 2007 7:00 pm

### Re: SECTORIAL ANTENNA

THANK YOU
SO THE BEST IS TO PLACE THEM EVEN WITHA THE TOWER?

jacoblydon
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Posts: 100
Joined: Tue Jun 12, 2007 11:51 pm
Location: Arkansas

### Re: SECTORIAL ANTENNA

It is fairly simple to run test and see which coverage is best for your location. Just set up as client and go for a drive. Start out from the base of the tower and drive showing signal the whole way. What wattage of cards do you use in AP?

omar_1966
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Joined: Mon Oct 01, 2007 7:00 pm

### Re: SECTORIAL ANTENNA

I AM USING 600 MW CARDS IN 3 SECTORIAL ANTENNAS, I AM USING THEM PARALEL TO THE TOWER I AM NOT USING THE TILT BRACKET BUT, SOME BODY TOLD ME THAT THEY MUST HAVE SOME TILT EVEM FOR LONG DISTANCE COVERAGE.

tgrand
Long time Member
Posts: 671
Joined: Mon Aug 21, 2006 2:57 am

### Re: SECTORIAL ANTENNA

Do the math...
Ie if beamwidth is 7 deg and the tower is 80 ft.
The formula would be :

Void = 80 * tan ( 90 - ( 7 / 2) ).

Void = Height * tan( 90 - ( beamwidth / 2 ))

Void being the disance until full signal hits the ground.
If you lowest client height is expected to be 15ft then instead of 80 use 80-15.

I doubt that anyone is going to put a client on the ground.

Anything within that distance should be tested as this zone is the overshot zone.
You may have to put the clients up a little higher in this zone, or use larger than expected antennas... All depends on the APs eirp, trees, etc.

cmacneill
Member Candidate
Posts: 294
Joined: Sun Apr 01, 2007 10:51 pm
Location: Christchurch, New Zealand

### Re: SECTORIAL ANTENNA

This assumes a flat landscape, don't forget to use absolute altitudes above sea level where the topography is anything other than flat as a pancake!

As a rule of thumb where all client antennae are at a lower altitude than the main transmitter then down tilt by at least half the antenna's vertical beam width, otherwise you're just sending the signal into Space.

I created an Excel spreadsheet a couple of years ago, it calculates the signal footprint given various elevation differences and distances for different antenna types.

I tried to attach the spreadsheet to this post, but I'm getting weird errors, so I've made the spreadsheet available at http://www.glenkens.uk.net/files/downtilt.xls.

tgrand
Long time Member
Posts: 671
Joined: Mon Aug 21, 2006 2:57 am

### Re: SECTORIAL ANTENNA

Yes I agree that these have to be given consideration...

That said, the formula I have given can be adjusted for downtilt by adjusting the angle, and the terain by adjusting the Height.