What is the difference between the 301121 and 301123 dome antennas?
Wilson offers two different dome building antennas for fixed, internal building use.  
Below are the similarities and the differences between these two antennas.
301121
  
301123
Shape
Both of these are cellular
dome antennas.  There is a
bit of shape difference the
301123 is a bit flatter and
the 301121 has a more
rounded end.  

The flat nose end of the
301123 allows the antenna
to be set above an
elevated ceiling without any
mounting.  Just set it on the
suspended ceiling tile.
8 inches / 20.32 cm
Size - Diameter
7.72 inches / 19.6 cm
Less than 1 lb.
Weight
Less than 1 lb.
Glossy finish.  A little nicer
looking.
Finish
Flat finish
59.95
Cost
59.95
Dual-band
Dual-band
Both antennas are
dual-band and work with
both 800 and 1900MHz
cellular amplifiers
Dual-Band

Some Wilson spec sheets
and the Issue 7 (2006)
catalog mistakenly said this
was only an 800MHz
antenna
Vertical
Think of this antenna like a
lighthouse.  A focused
signal that fans outward
and around.  This dome
has the best distance, but
the cell signal does not
travel downward as well as
the 301123.  This antenna
is best for single floor
implementations.
Polarization

In the cellular antenna world
Vertical Polarization means
outward and
Horizontal Polarization means
up/down
Vertical & Horizontal
Think of this antenna as a
glowing light.  It does not
travel out as far as the
301121 but the cell signal
travels down and all around
like a light bulb.  This
antenna should be used if
you want to penetrate the
floor below with a cell
signal.  Best for two floor
environments with the
dome on the ceiling of the
upper floor.
Come with a N-Female.  
Fits onto Wilson 9913 low
loss building cable
Connectors
Comes with a N-Female
connector.  Fits onto
Wilson 9913 low loss cable.
Summary
Both of these cellular dome antennas will work well in a building environment.  Use the
301121 if you have a single floor situation and use the 301123 if you have a multiple
floor situation.  The 301123 is easier to mount and has a pigtail that can be run out the
side of the dome.  I have also used the 301123 on a wall where it does a good job of
projecting the signal across the room.

I hope this information helps you with your selection.