Manual

WI-I/O 9-x Wireless Module User Manual v2.16

WI-I/O-EX-1-S-x Serial Module

Page 14

The Yagi gain also acts on the receiver, so adding Yagi antennas at both ends of a link provides a

double improvement.

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.

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-I/O 9-x

Antenna installed

with drain holes

down

Coax feed

looped

Protected area -

approx 45 deg angle

to vertical