MDS 05-3316A01, Rev. E
MDS 4710B/9710B I/O Guide
9
2.5 Antennas and Feedlines
Antennas
The transceiver can be used with a number of antennas. The exact style
depends on the physical size and layout of the radio system. A direc-
tional Yagi (Figure 7) or corner reflector antenna is generally recom-
mended at remote sites to minimize interference to and from other users.
Antennas of this type are available from several manufacturers.
Invisible place holder
Figure 7. Typical Yagi antenna (mounted to mast)
The selection of antenna feedline is very important. Poor quality cables
should be avoided as they will result in power losses that may reduce the
range and reliability of the radio system.
Table 2 and Table 3 show the losses that will occur when using various
lengths and types of cable at 400 and 900 MHz, respectively. Regardless
of the type used, it should be kept as short as possible to minimize signal
loss.
Table 2. Length vs. loss in coaxial cables at 400 MHz
Cable Type
10 Feet
(3.05 Meters)
50 Feet
(15.24 Meters)
100 Feet
(30.48 Meters)
500 Feet
(152.4 Meters)
RG-8A/U
0.51dB
2.53 dB
5.07 dB
25.35 dB
1/2 inch HELIAX
0.12 dB
0.76 dB
1.51 dB
7.55 dB
7/8 inch HELIAX
0.08 dB
0.42 dB
0.83 dB
4.15 dB
1 1/4 inch HELIAX
0.06 dB
0.31 dB
0.62 dB
3.10 dB
1 5/8 inch HELIAX
0.05 dB
0.26 dB
0.52 dB
2.60 dB
