GE MDS Mercury 3650, Reference Manual

Page: 176 / 211

05-4446A01, Rev. E Mercury Reference Manual 167
Diversity Reception (RX2) Antenna Port
Functional on some models. The RX2 antenna port allows connection of
a second antenna to the transceiver for space diversity reception.
GPS Antennas
A number of GPS antennas (both active and passive) are available for
use with the transceivers. Consult your factory representative for more
information.
Feedlines
Carefully consider the choice of feedline used with the antenna. Avoid
poor-quality coaxial cables, as they degrade system performance for
both transmission and reception. A low-loss cable type such as Heliax
®
is recommended that is suitable for the frequency of operation. Keep the
cable as short as possible to minimize signal loss.
Table 5-1 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 depends on the required length, cost con-
siderations, and the acceptable amount of signal loss.
Table 5-1 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 depends on the required length, cost considerations, and the
acceptable amount of signal loss.
Table 5-1. 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 5-2. Length vs. Loss in Coaxial Cables at 3600 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 3.04 dB 15.2 dB Unacceptable
Loss Unacceptable Loss
LMR-400 1.56 dB 7.8 dB 15.6 dB Unacceptable Loss