Powerwave Technologies NEXUS FT, Installation And Service Manual, Page: 33 / 51

Nexus FT Commissioning
044-05251 Rev B 3-9
Passive Intermodulation (PIM) Testing
PIM is the non-linear effect of passive RF components in a desired RF transmission band. As higher per-
carrier transmit power levels are applied to duplexed passive RF networks, PIM becomes an increasingly
significant factor in potential receiver desensitization. A PIM tester may be used on the RF network prior to
turn-on and commissioning of the unit, but if a PIM tester is not available, the following may be used:
The following equipment is required to test for PIM:
❑
Anritsu Site eMaster or equivilent RF Spectrum Analyzer
❑
Agilent ESG4432B or equivilent Multi-Signal Generator (or commissioned BTS)
❑
Guarateed/calibrated PIM load capable of handling 20W composite power
❑
Low-PIM RF cable adaptors such as N-N female, Din male to N femaile, DIN-DIN, SMA-SMA
female, and N male to SMA female
❑
Installed and operational WRH unit
❑
Installed passive RF network under test
❑
Torque wrenches for DIN and N connectors
Two different types of setup are available, depeding on equipment availability and testing methods.
Figure 3-10 shows PIM testing with two carriers over one WRH, and Figure 3-11 shows PIM testing with one
carrier over each of two WRHs.
Figure 3-10 PIM testing two carriers and one WRH
Figure 3-11 PIM testing one carrier over each of two WRHs
The following PIM test uses the receive sensitivity and gain of the WRH under test to verify that the receive
path is free of PIM noise. For PIM to be a problem at a particular site, TX signals must exist such that their
products fall into the RX band using the formulae:
3
rd
order product = (2 * f
1
) - f
2
and
3
rd
order product = (2 * f
2
) - f
1
WRH-V
E4432B
SIG Gen
(or BTS)
E4432B
SIG Gen
(or BTS)
Load /
DAS
Σ
OCM
E4402B
Spec. An.
WRH-V
Under Test
E4432B
Sig Gen /
BTS 1
Load /
DAS
OCM
E4402B
Spec. An.
WRH-V
Hybrid
OCM
E4432B
Sig Gen /
BTS 2