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Contributor
Posts: 32
Registered: ‎08-29-2016

Tilt with beam forming antennas

Hi. 

Traditionally, we would fine adjust the elevation of a sector once we had a few clients (sorry SM's) connected. 

Using the beam forming antenna, this process doesnt work as well as the antenna will compensate for changes in the elevation (As I understand it - maybe I'm wrong but does it beam form in the vertical plane as well as the horizontal, is this what the H and V degrees mean?)

 

Given the above, is has anyone a favourite procedure for optimising the elevation when using the beam forming antenna theyd like to share?

Thanks

Valued Contributor
Posts: 905
Registered: ‎07-17-2009

Re: Tilt with beam forming antennas

the smart antenna will handle being installed at 0 degrees, but very near clients will likely benefit from sector tilt.  2nd major note.   the 2nd part of tilting a sector is to control its beam reach,  if you've got a sector 300' above your audience with a 7 degree beam, and you tilt it 3.5 degrees, your signal will be on the horizon, though this may not bother you now, you could end up running around having to tilt sectors down the road.   matching your tilt to your targets is always important to help control your noise floor. 

 

 

the for mentioned antenna tilted to 4 degrees, would have an outer radius of 6.5 miles .    a tower 6 miles away will hear that sector significantly less.   makes reuse better, and noise tolerance even better. 

Contributor
Posts: 32
Registered: ‎08-29-2016

Re: Tilt with beam forming antennas

Is there any electrical beam tilt already in the new Cambium sectors (and also the smart beamforming antenna, ie is it predisposed to look down a few degrees if mounted exactly at 90 degrees to the horizontal)?

I know that the UBNT antennas often end up looking up to the sky a few degrees at low sites.

Valued Contributor
Posts: 611
Registered: ‎12-04-2007

Re: Tilt with beam forming antennas

I don't know what the inbuilt downtilt is on the new sector antennas, but the steering panel for the ePMP2000:  shouldn't need downtilt really, given it's nature, and in fact will match the mechanical downtilt of the sector anyway, assuming it's mounted to the bottom.

 

As far as alignment to optimize downtilt, I'd just disconnect the steering antenna during the process then reconnect it once finished.  Since it's used only for uplink data it will definitely interfere with your ability to judge downtilt if looking at the AP's received signal levels for various clients.

 

As for the V and H angle stats, Cambium helpfully cleared that up for me a while back - What it's reporting is the left-to-right position of each client, for Horizontal and Vertical polarizations.  So essentially two radios (H and V) reporting how far each client is left or right from the center of the sector.  You'd expect them to be the same angle, but in the real world they usually differ by a bit.  Presumably it DOES beam-form two-dimensionally, but the angles reported are strictly across the sector horizontally.

 

j

Trusted Contributor
Posts: 1,155
Registered: ‎01-05-2014

Re: Tilt with beam forming antennas

[ Edited ]

EI3HG wrote:

Is there any electrical beam tilt already in the new Cambium sectors (and also the smart beamforming antenna, ie is it predisposed to look down a few degrees if mounted exactly at 90 degrees to the horizontal)?

I know that the UBNT antennas often end up looking up to the sky a few degrees at low sites.


The new 90/120 deg antenna, PN C050900D021A, has -2 degrees of electrical downtilt.

 

This antenna is designed for and recommended to be used with the optional beam steering antenna aka BSA. The BSA mounts to the bottom of the antenna. Any mechancial tilt added to the antenna will also be added to the BSA. Using the BSA with 3rd party antennas is not recommended as the gain and characteristics of the BSA are designed around the Cambium sector's specifications.

 

For instance, I tried using a BSA with UBNT 45 degree sector and found that very few of the clients would use the BSA because the gain on the sector was so high and the beamwidth so tight. This renders the BSA in this configuration useless.