Microwave Data Systems MDS entraNET 2400 Especificaciones descargar pdf (Pagina 116)

108 MDS entraNET 900 System Guide MDS 05-4055A01, Rev. A

Invisible place holder

Figure 6-5. 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.

For cable runs of less than 20 feet (6 meters), or for short range trans-

mission, an inexpensive type such as Type RG-8A/U may be acceptable.

Otherwise, we recommend using a low-loss cable type suited for

900 MHz, such as Andrew Corp. Heliax

Table 6-1 lists several types of popular feedlines and indicates the signal

losses (in dB) that result when using various lengths of cable at

900 MHz. The choice of cable will depend on the required length, cost

considerations, and the amount of signal loss that can be tolerated.

Table 6-1. Length vs. loss in coaxial cables at 900 MHz

Cable Type

10 Feet

(3.05 m)

50 Feet

(15.24 m)

100 Feet

(30.48 m)

500 Feet

(152.4 m)

LMR-400 0.39 dB 1.95 dB 3.90 dB Unacceptable

Loss

1/2 inch HELIAX 0.23 dB 1.15 dB 2.29 dB 11.45 dB

7/8 inch HELIAX 0.13 dB 0.64 dB 1.28 dB 6.40 dB

1-1/4 inch HELIAX 0.10 dB 0.48 dB 0.95 dB 4.75 dB

1-5/8 inch HELIAX 0.08 dB 0.40 dB 0.80 dB 4.00 dB

1 2 ... 111 112 113 114 115 116 117 118 119 120 121 ... 147 148

Sin comentarios

Microwave Data Systems MDS entraNET 2400 Especificaciones Pagina 116