Bird Technologies Group 5PI613805 Manual De Usuario
TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 11
61-38-05 UserMan page 11 of 38
Test Equipment
The following equipment is required in order to per-
form the pre-installation measurements.
The following equipment is required in order to per-
form the pre-installation measurements.
1) Signal generator for the frequencies of interest
capable of a 0 dBm output level. Modulation is
not necessary.
not necessary.
2) Spectrum analyzer that covers the frequencies
of interest and is capable of observing signal
levels down to -100 dBm.
levels down to -100 dBm.
3) Double shielded coaxial test cables made from
RG142 or RG55 coaxial cable.
Antenna Isolation
Antenna isolation is the signal path isolation
between the two sections of the signal distribution
system that are to be connected to the signal
boosters antenna ports. Lack of sufficient isolation
between the input and output antennas can cause
the amplifiers in the system to oscillate. This can
happen at a high enough level to damage the
power amplifier stages. In general, if one or both
antenna ports are connected to sections of radiat-
ing coaxial cable (lossy cable) via short jumpers of
Antenna isolation is the signal path isolation
between the two sections of the signal distribution
system that are to be connected to the signal
boosters antenna ports. Lack of sufficient isolation
between the input and output antennas can cause
the amplifiers in the system to oscillate. This can
happen at a high enough level to damage the
power amplifier stages. In general, if one or both
antenna ports are connected to sections of radiat-
ing coaxial cable (lossy cable) via short jumpers of
non-radiating cable the isolation will be more than
adequate because of the high coupling loss values
that are encountered with this type of cable. When
a network of antennas are used for the input and
output, this problem is much more likely. Isolation
values are relatively easy to measure with a spec-
trum analyzer and signal generator.
adequate because of the high coupling loss values
that are encountered with this type of cable. When
a network of antennas are used for the input and
output, this problem is much more likely. Isolation
values are relatively easy to measure with a spec-
trum analyzer and signal generator.
Procedure for Measuring Antenna Isolation
1) Set the signal generator for a 0 dBm output
1) Set the signal generator for a 0 dBm output
level at the center frequency of one of the signal
boosters passbands.
boosters passbands.
2) Set the spectrum analyzer for the same center
frequency and a sweep width equal to or just
slightly greater than the passband chosen in
step one.
slightly greater than the passband chosen in
step one.
3) Connect the test leads of the signal generator
and the spectrum analyzer together using a
female barrel connector, see Figure 4. Observe
the signal on the analyzer and adjust the input
attenuator of the analyzer for a signal level that
just reaches the 0 dBm level at the top of the
graticule.
female barrel connector, see Figure 4. Observe
the signal on the analyzer and adjust the input
attenuator of the analyzer for a signal level that
just reaches the 0 dBm level at the top of the
graticule.
INTERNAL
SIGNAL DISTRIBUTION
SYSTEM
SPECTRUM
ANALYZER
ANALYZER
EXTERNAL
ANTENNA
ANTENNA
SIGNAL
GENERATOR
ZERO LOSS
REFERENCE
ISOLATION (dB)
Figure 4: Typical test equipment setup for measuring antenna isolation.