NORMARC NM 7000 Series, Installation & Commissioning Handbook

Page: 113 / 189

Measure return phase for the upper antenna cable (A2). Then take into account the phase
centres of the Antenna given in the factory data sheet. Determine if one of the cables should
be trimmed in order to comply with phase equality tolerance for the set of antennas.
Tolerance: ±1.0° true electrical cable length including Antenna phase centre deviation. (if
available)
See measurement set-up diagram Figure 7-1 below
:
Figure 7-1 Cable phasing measurement set-up.
7.2.2 Monitor return cable length
Measure return phase as described in (62.0) for both monitor cables. Check that initial values
are within ±1.5° true phase (±3.0° return phase).
7.2.3 Phase and amplitude transfer measurement
Connect each antenna cable and monitor cable to Antenna load and source respectively. Uti-
lise a vector voltmeter or network analyser in a test set-up Figure 7-2, and measure relative
transfer phase and amplitude for the upper antenna cable (A2) in reference to the lower
antenna (A1).
Figure 7-2 Phase and amplitude transfer measurement set-up.
20dB
A B
VECTOR
From cabinet
CSB BNC o/p
CABLE UNDER TEST
OPEN END
DIR. COUPL.
20dB
A B
VECTOR VOLTMETER
A(n)
M(n)
From cabinet
CSB BNC o/p
Ant.
DIR. COUPL.