User's Manual

MDS 05-6302A01, Rev. A MDS Mercury 16E Technical Manual 43
Antennas
The equipment can be used with a number of antennas. The exact style
used depends on the physical size and layout of a system. Contact your
factory representative for specific recommendations on antenna types
and hardware sources.
In general, a sector type antenna is used at the Base Station site. This
provides equal coverage to all of the Subscriber sites.
At Remote Gateway sites and units in point-to-point LANs, a directional
Yagi (Figure 24) antenna is generally recommended to minimize
interference to and from other users. Antennas are available from a
number of manufacturers.
Invisible place holder
Figure 24. Typical Yagi Antenna (mounted to mast)
Feedlines
The choice of feedline used with the antenna should be carefully consid-
ered. Poor-quality coaxial cables should be avoided, as they will
degrade system performance for both transmission and reception. The
cable should be kept as short as possible to minimize signal loss. We
recommend using a low-loss cable type suited for the frequency of oper-
ation, such as Heliax
®
.
Table 6-1 lists several types of popular feedlines and indicates the
approximate signal losses (in dB) that result when using various lengths
of cable at 1800 MHz. Note that losses will be approximately doubled
for 3650 MHz and tripled for 5800 MHz. The choice of cable will
depend on the required length, cost considerations, and the amount of
signal loss that can be tolerated.