5 Ghz 90/120 Degree Sector Antenna Specifications

First of all, I am an RF design and electrical engineer with over 55 years in the business.

Secondly, we recently purchased several 5 Ghz 90/120 Degree Sector Antennas.

Being an RF design engineer, I was expecting the 5 Ghz 90/120 degree antennas to be field modifiable to increase or decrease the beamwidth of the antenna. In this case, the antenna should have been field modifiable to allow the antenna to have a 90 OR A 120 degree beamwidth.

In the commercial antenna world, if an antenna is advertised with two different bandwidths, it would normally have a small piece of metal on each side of the antenna to reduce the beamwidth of the radiation pattern.

With the installation of the metal pieces on each side of the antenna, the antenna beamwidth would be reduced. Removing the metal pieces from both sides of the antennas would cause the radiated pattern to be wider.

It is understood in the commercial antenna world, that the beamwidth of an antenna is specified as the point on each side of the main lobe when the radiated signal is reduced by 3 DB.

The instructions that come in the box with the
5 Ghz 90/120 Degree Sector Antenna say absolutely NOTHING about the beamwidth of the antenna.

I finally some a data sheet on the ePMP-2000 radios that gave some information about the beamwidth of this antenna.

I about fell over when I read the specifications on the antenna. The 90 degree beamwidth is specified as 3 db. That is fine.

Then the spec sheet says that the 120 degree beamwidth is 6 DB. Really?

Cambium might as well relabel and sell the antenna as a 90/120/150 degree antenna.

It makes absolutely no sense to specify the beamwidth of a sector antenna with anything other than a 3 DB reduction of of the main lobe, as every one else in the commercial industry does.

To those in the industry that know… this is nothing but false advertising by Cambium!

This is standard advertising practice in the wisp world and has been for quite a few years. At least since UBNT started advertising all of their antenna beamwidths at the 6db down point.

It is absolutely meaningless to advertise what the beamwidth is a 6 db down.

6 DB reduction in signal is dividing the signal that you would receive if the sector antenna is pointed directly at you by four (4). A 6 DB reduction is a major reduction in signal strength.

We don’t pay any attention to what UBNT might publish. When we looked at their stuff years ago, it was obvious that they were cooking the books with their numbers.

just some similar examples to show you that many antenna vendors show 6dB power BW as 120deg:

but I see your point as many antenna vendors do quote azimuth beam-width relative to the half-power points. Our datasheet is pretty clear that it is for 90deg and 120deg and gives the 3dB and 6dB power beam-widths:

good feedback though and we should consider this when marketing our antennas. I myself have not seen unlicensed antennas which have modifiable beam-widths as we normally must Certify the radios with specific antenna types\gains.