905U-L Wireless I/O Installation Manual
905U-L Wireless I/O
Page 19 of 40
Version 1.9
Yagi antennas
Yagi antennas are directional and have positive gain to the front of the antenna and
negative gain in other directions. You can use the gain to:
Compensate for coaxial cable loss for transmitter unit
; and
Increase receive sensitivity for receiver units
.
You should install Yagi antennas with the central beam horizontal and pointed directly in
the transmission direction to benefit from the antenna gain.
Note
Yagi antennas usually have a drain hole on the folded element. You should position the
drain hole at the bottom when installing the antenna.
You can install Yagi antennas:
Vertically polarized
– with the elements in a vertical plane; or
Horizontally polarized
– with the elements in a horizontal plane.
The following table shows the recommended installation mode for different situations.
If your installation has
…
ELPRO recommends using
…
Two stations both using Yagi antennas
Horizontal polarization for the stations.
Two or more stations communicating with a
common station
Vertical polarization for the stations; and
Dipole or collinear (i.e. non-directional) antenna for the
central station.
