MDS entraNET 2400, Installation And Operation Manual

Page: 159 / 208

MDS 05-4055A01, Rev. C MDS entraNET System Guide 151
For 900 MHz systems with cable runs of less than 20 ft./6m, an inexpen-
sive cable type such as Type RG-8A/U may be acceptable. For longer
runs, or for 2400 MHz systems, we recommend using a low-loss cable
type such as Andrew Corp. HELIAX
® cable.
The choice of cable depends on the required length, cost considerations,
and the amount of signal loss that can be tolerated.
Table 6-1 lists sev-
eral types of popular feedlines and indicates the signal losses (in dB) that
result when using various lengths of cable at 900 MHz.
Table 6-2 shows
the same data for 2400 MHz systems.
.
Maintaining Compliance at 900 MHz
(U.S.A. and Canada Only)
Table 6-3 outlines the minimum lengths of RG-214 coaxial cable that
must be used with common MDS omnidirectional antennas to maintain
compliance with the FCC and IC maximum limit of +36 dBm for
license-free 900 MHz systems.
Table 6-1. Length versus 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
Table 6-2. Length versus Loss in Coaxial Cables at 2400 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 0.70 dB 3.50 dB 6.61 dB Unacceptable
Loss
1/2 inch HELIAX 0.35 dB 1.73 dB 3.46 dB 17.3 dB
7/8 inch HELIAX 0.20 dB 0.99 dB 1.97 dB 9.85 dB
1-1/4 inch HELIAX 0.15 dB 0.73 dB 1.45 dB 7.50 dB
1-5/8 inch HELIAX 0.13 dB 0.63 dB 1.25 dB 6.25 dB
Table 6-3. Minimum Feedline Length versus Antenna Gain
(RG-214 coaxial cable)
Antenna Gain
(dBd) Antenna Gain
(dBi) Minimum Feedline
Length (Loss in dB) Power Level
at Minimum Length
Unity (0 dB) 2.15
dBi
3 meters (1.0 dB) +31.15 dBi
3 dBd 5.15 dBi 3 meters (1.0 dB) +34.15 dBi
5 dBd 7.15 dBi 3.1 meters (1.2 dB) +35.95 dBi