User Manual

MDS 05-4670A01, Rev. E SD Series Reference Manual (x710 Mode) 11
4.3 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 your radio system. A direc-
tional Yagi (Figure 10) 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,
including GE MDS. Contact your factory representative for details.
Invisible place holder
Figure 10. Typical Yagi Antenna (mounted to mast)
Feedlines
The selection of an antenna feedline is very important. Poor quality
cable should be avoided as it will result in power losses that might
reduce the range and reliability of the radio system.
Table 2, Table 3, and Table 4 show the approximate losses that will
occur when using various lengths and types of coaxial cable in the 200,
400, and 900 MHz bands. Regardless of the type used, the cable should
be kept as short as possible to minimize signal loss.
Table 2. Signal Loss in Coaxial Cables (at 200 MHz)
Cable Type
10 Feet
(3.05 Meters)
50 Feet
(15.24 Meters)
100 Feet
(30.48 Meters)
200 Feet
(60.96 Meters)
RG-8A/U 0.26 dB 1.27 dB 2.5 dB 5.07 dB
1/2 inch HELIAX
0.06 dB 0.38 dB 0.76 dB 1.60 dB
7/8 inch HELIAX
0.04 dB 0.21 dB 0.42 dB 0.83 dB
1-1/4 inch HELIAX
0.03 dB 0.16 dB 0.31 dB 0.62 dB
1-5/8 inch HELIAX
0.025 dB 0.13 dB 0.26 dB 0.52 dB