WI-MOD-9-D
Radio Modem
User Manual v1.9
WI-MOD-9-D
Manual
v 1.9
Page
14
Yagi antennas are directional. That is, they have positive gain to the front of the antenna, but
negative gain in other directions. Hence Yagi antennas should be installed with the central beam
horizontal and must be pointed exactly in the direction of transmission to benefit from the gain of
the antenna. The Yagi antennas may be installed with the elements in a vertical plane (vertically
polarised) or in a horizontal plane (horizontally polarised). For a two station installation, with
both modules using Yagi antennas, horizontal polarisation is recommended. If there are more
than two stations transmitting to a common station, then the Yagi antennas should have vertical
polarisation, and the common (or “central” station should have a collinear (non-directional)
antenna.
Also note that Yagi antennas normally have a drain hole on the folded element - the drain hole
should be located on the bottom of the installed antenna.
WI-MOD-9-D
Antenna installed
with drain holes
down
Coax feed
looped
90
o