User's Manual

Installation Requirements
31
Horizon Compact Release 1.01.01 Wireless Ethernet Product User Manual – Volume 1
7.1.2.1 UL24 Antenna Information
This dev ice has been designed to operate with the antennas listed below, and having a maximum gain of
43.7 dBi. Antennas not included in this list or having a gain greater than 43.7dBi are strictly prohibited for
use with this device. This device has integrated antennas.
24UL Antenna Data
1 foot Andrews VHLP1-26DW 36.2dBi
2 foot Andrews VHLP2-26DW 40.8dBi
2.5 foot Andrews VHLP2.5-26DW 43.7dBi
7.2 Antenna Location
For both licensed and unlicensed systems, antenna location, relative to nearby obstacles, is an important
factor to consider when planning an installation. For systems mounted on buildings, roof edges and
parapets, the roof surface itself, air conditioning plant, other antenna systems, walls and overhead objects
are all considered potential obstacles. On tower mounted systems you must consider the proximity of
other antenna systems and mounting hardware.
Near field effects, resulting from a number of minor radiation lobes normally found around antenna
systems, can reflect off nearby objects and interfere with the normal reception of the radio. Reflected
waves can also change their polarity. This is especially important for unlicensed systems.
Consider an unlicensed installation that transmits with vertical polarity and receives with horizontal
polarity. If the near field vertically polarized transmitted signal reflects off an obstacle located too close to
the antenna system, then the reflected signal changes its polarity to horizontal, which is the same polarity
as the receiver. This causes the receiver to “swallow” the transmitted signal, resulting in receiver
“swamp ing”, excessive noise and the inability to receive the signal from the far end of the link. Ensuring
that obstacles and objects are not too close to the antenna system will avoid this problem.
As a “rule of thumb”, for both licensed and unlicensed installations, ensure that you maintain
an angle of 45 degrees, or greater, between the far side of the highest part of an obstacle and
the underside of the antenna.
Figure 7-3 illustrates this approach. Also, remember to apply this rule in all directions around the antenna,
above, below and to each side. An exception to this rule can be applied when the antenna is positioned
12.5 m (40 ft) or more from the edge of a roof clear of obstacles (a roof edge is considered an obstacle).
In this case the antenna need not be higher than 2.5 m (8 ft) above the roof surface. For more details on
antenna placement for unlicensed systems refer to Volume 2 of this manual.
Figure 7-3 Recommended Antenna Placement
Roof
Line
P
>45
°
Roof
Line
2.5 m
P
up
to and
greater than
12.5 m
Roof
Line
O
>
30 cm
30 cm