Community discussions

MUM Europe 2020
 
omar_1966
just joined
Topic Author
Posts: 21
Joined: Mon Oct 01, 2007 7:00 pm

SECTORIAL ANTENNA

Thu Nov 29, 2007 8:57 am

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???

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

Re: SECTORIAL ANTENNA

Thu Nov 29, 2007 1:10 pm

my sectors are 30m high and i didint give any tilt. works fine
 
omar_1966
just joined
Topic Author
Posts: 21
Joined: Mon Oct 01, 2007 7:00 pm

Re: SECTORIAL ANTENNA

Thu Nov 29, 2007 5:41 pm

THANK YOU
SO THE BEST IS TO PLACE THEM EVEN WITHA THE TOWER?
 
User avatar
jacoblydon
Member Candidate
Member Candidate
Posts: 100
Joined: Tue Jun 12, 2007 11:51 pm
Location: Arkansas

Re: SECTORIAL ANTENNA

Fri Nov 30, 2007 6:04 am

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
just joined
Topic Author
Posts: 21
Joined: Mon Oct 01, 2007 7:00 pm

Re: SECTORIAL ANTENNA

Fri Nov 30, 2007 8:44 am

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.
 
User avatar
tgrand
Long time Member
Long time Member
Posts: 671
Joined: Mon Aug 21, 2006 2:57 am
Location: Winnipeg, Manitoba, Canada

Re: SECTORIAL ANTENNA

Fri Nov 30, 2007 1:07 pm

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

Re: SECTORIAL ANTENNA

Fri Nov 30, 2007 2:00 pm

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.
 
User avatar
tgrand
Long time Member
Long time Member
Posts: 671
Joined: Mon Aug 21, 2006 2:57 am
Location: Winnipeg, Manitoba, Canada

Re: SECTORIAL ANTENNA

Fri Nov 30, 2007 2:59 pm

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.
The adjustments only require simply addition, and subtraction.

When dealing wth Kms convert the antenna height to meters first.

Who is online

Users browsing this forum: No registered users and 19 guests