MDS 05-4846A01, Rev. H
SD Series Technical Manual
21
Invisible place holder
Figure 15. 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 may reduce
the range and reliability of the radio system.
The tables which follow show the approximate losses that will occur
when using various lengths and types of coaxial cable in the 200, 400
and 900 MHz bands, respectively. Regardless of the type used, the cable
should be kept as short as possible to minimize signal loss.
Table 3. Signal Loss in Coaxial Cables (at 200 MHz)
Cable Type
10 Feet
(3 Meters)
50 Feet
(15 Meters)
100 Feet
(30.5 Meters)
200 Feet
(61 Meters)
RG-8A/U
0.26 dB
1.27 dB
2.50 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
Table 4. Signal Loss in Coaxial Cables (at 400 MHz)
Cable Type
10 Feet
(3 Meters)
50 Feet
(15 Meters)
100 Feet
(30.5 Meters)
200 Feet
(61 Meters)
RG-8A/U
0.51 dB
2.53 dB
5.07 dB
10.14 dB
1/2 inch HELIAX
0.12 dB
0.76 dB
1.51 dB
3.02 dB
7/8 inch HELIAX
0.08 dB
0.42 dB
0.83 dB
1.66 dB
1-1/4 inch HELIAX
0.06 dB
0.31 dB
0.62 dB
1.24 dB
1-5/8 inch HELIAX
0.05 dB
0.26 dB
0.52 dB
1.04 dB
