I just purchased four sectors assuming these were 90 degrees as the description advertised, but I noticed on the box they say "90/120". Upon doing some more research I found Cambium's documentation for this antenna which explains a "3dB beamwidth" = 90 degrees while a "6dB beamwidth" = 120 degrees.
This is confusing for me... How do I determine whether I'm operating in a 90 degree swath or a 120? I can't seem to find any reference to "beamwidth" gain on my ePMP 1000s...
Also, which is recommended? 90 or 120? I assume(d) 90 is best.
I absolutely could not understand what you would set to a 3dB/6dB gain and why it would dictate the beamwidth! Why is this explained absolutely nowhere?
I absolutely could not understand what you would set to a 3dB/6dB gain and why it would dictate the beamwidth! Why is this explained absolutely nowhere?
Hi,
The beamwidth of the antenna is the width of the main lobe, usually specified by the half power beam width, the angle encompassed between the points on the side of the lobe where the power has fallen to half (-3 dB) of its maximum value.
So for current antenna you have 90 degrees for -3dB level and 120 degrees for -6dB level.
These roll off numbers are actually included with most reputable antennas. In many instances you can use a sector antenna for more then the advertised beamwidth, albiet with a loss near the edges. Some patterns and manufactures are better then others at allowing you to fudge this. Cambium designed this antenna specifically for both 90 and 120deg use.
Most people just buy a specific deg beamwidth antenna and leave it at that... so there's no reason for them to really know/understand what the roll off numbers are. I do agree, Cambium could do a bit better explaining how this works. There's been a number of confused people that come to the forum here and want to know what the 90/120 thing is all about.
