GE MDS iNET Series, Reference Manual

Page: 123 / 173

05-2806A01, Rev. L MDS iNET Series Reference Manual 111
Table 4-1 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 con-
siderations, and the amount of signal loss that can be tolerated.
The tables below outline the minimum lengths of RG-214 coaxial cable that must be used with common GE
MDS omnidirectional antennas in order to maintain compliance with FCC maximum limit of +36 dBi. If
other coaxial cable is used, the appropriate changes in loss figures must be made.
NOTE:
The authority to operate the transceiver in the USA may be void if antennas other than those
approved by the FCC are used. Contact your factory representative for additional antenna infor-
mation.
*Refer to Table 4-3 for allowable power settings of the transceiver for each antenna type.
NOTE:
There is no minimum feedline length required when a 6 dBi gain or less antenna is used, as the
EIRP will never exceed 36 dBm which is the maximum allowed, per FCC rules. The transceiver’s
RF output power may only be adjusted by the manufacturer or its sub-contracted Professional
Installer.
The MDS iNET-II Transceiver is factory set to +29 dBm power output to maintain compliance
with the FCC’s Digital Transmission System (DTS) Part 15 rules. These rules limit power to a
maximum of 8 dBm/3 kHz, thus the iNET-II Transceiver is factory set to +29 dBm. When calcu-
lating maximum transceiver power output for iNET-II installations, use +29 dBm if antenna gain
is 6 dBi or less. See “How Much Output Power Can be Used?” on Page 112 for power control of
higher gain antennas.
Table 4-1. 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)
RG-214 .76 dB 3.8 dB 7.6 dB Unacceptable
Loss
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 4-2. Feedline Length vs. Antenna Gain*
(Required for Regulatory compliance)
Antenna
Gain (dBd) Antenna
Gain (dBi) Minimum Feedline
Length (Loss in dB)
EIRP Level @
Min. Length Maxrad Antenna
Part No.
Unity (0 dB) 2.15 dBi No minimum length +32.15 dBm Omni #MFB900
3 dBd 5.15 dBi No minimum length +35.15 dBm Omni # MFB900
5 dBd 7.15 dBi 3.1 meters (1.2 dB) +35.95 dBm Omni # MFB900
6 dBd 8.15 dBi 9.1 meters (2.2 dB) +35.95 dBm Yagi # BMOY8903
9.2 dBd 11.34 dBi 25 meters (5.34 dB) +36.00 dBm Yagi OGB9-915