Beamforming
means selecting a beam whose shape matches with the area of interest (where
user/group of users are located) and then steering the beam towards that area.
Now the question is what defines the
shape of the beam?
Panel Antenna is usually categorized in terms of
horizontal beamwidth and length,
thats the reason we don't get an idea of Beams shape from the way the panel antennas are catagorized. The dimensions of the beam are vertical beamwidth and horizontal beamwidth, given in the spec sheet.
Now let's collect the data of panel anetnna dimensions (length x width) for various beams and try to find any relationship between them, if there's any.
Download the
two sets of spec sheets of 2-port 800 MHz cross-polar antenna, from any panel
antenna manufacturing website for following two scenarios:
set#1) of a fixed length, say 8
ft, with different horizontal beamwidths (30/45/65/90 deg).
set#2)
of a fixed horizontal beamwidth, say 65 deg, with different lengths (2/4/6/8/10
ft).
Now make a
table of Panel-Antenna dimensions (length x width) Vs Beam dimensions (VBW x HBW).
You will find
an interesting relationship between the width of panel antenna to the horizontal
beamwidth from set#1, as the antenna becomes wider the horizontal beam width becomes narrower.
And that of length of the panel antenna to the vertical
beamwidth from set#2, as the antenna becomes taller the vertical beamwidth becomes narrower.
Now just bring
this concept from basic antenna theory into your mind that Directivity
increases with number of antenna elements in an array antenna (panel antenna)
And then you don't have to think twice about the association that you just found between panel antenna dimensions with that of beam's dimensions from the spec sheets of panel antennas.
Why we need a narrower beam in vertical direction than in horizontal? To get a more control on the radius of coverage.
In Beamforming part II, I will explain the steering of the beam, as we are done with the shape of the beam.
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