FAQs


 

How is PIM specified?

PIM should be specified as per your clients requirements. Typically it specified in absolute power (dBm) or relative power (dBc) to 2 test Tones. Note a -110 dBm IM signal caused by two +43 dBm tones can also be specified as a -153dBc IM level.

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What is a good PIM measurement level?

A level that is low enough not to effect the performance of the receiver. Quality components adhere to a PIM requirement at around the -110dBm (-153dBc) level. Antenna systems performing at better than -100dBm are considered as good.

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What are the most common causes of PIM?

From testing over 2000 feeder lines, 75% of problems are found in poor quality, poorly assembled, dirty connectors. Other contributors are poor component plating, ferromagnetic materials, low contact pressure (connectors not torque correctly).

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Is there an IEC standard for PIM?

IEC 62037 is the international standard for measuring PIM in passive components (connectors, cables, cable assemblies, waveguide assemblies and components...etc). www.iec.ch

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Is high power testing for PIM really necessary?

Testing for PIM at 40W has been demonstrated as a more stringent network test and a device that meets the desired PIM performance at 2W, may well fail if subjected to higher power levels of 20W or 40W. PIM tests that are performed at low power can also mask the presence of PIM, and although performing PIM testing at 40W is considered to be a more stringent test than is currently required, it exposes a cell site’s PIM vulnerabilities in a significantly more quantitative manner leaving little room for conjecture as to the integrity of the devices or components under test. See more info on what is pim testing.

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If we measure PIM, do we still need to measure RL /VSWR?

Yes. They are complimentary tests and both are required. RL measures the overall impedance matching of all components in the antennas system. PIM testing measures the linearity of the components in the antenna system.

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I need my analyzer every day – how can I prevent damage to the TX /RX connectors with the excessive mating /de-mating that takes place?

PiMPro analyzers are fitted with a ‘connector saver’ – a high quality in line adaptor that can be changed quickly and easily if damaged. Adaptors can also be used on PIM LOAD /Standard for the same reason. You need to ensure the performance is correct prior to measurements of DUT?

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How often should portable PIM test set be calibrated?

Calibration is annual. However the performance of the analyzer can be checked using a known PIM standard /LOAD.

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Are there companies that can be hired to test the health of antenna systems?

CCE offer a technical service in field with qualified technicians /engineers either supporting generic installations crew or independent using in house qualified climbers /riggers.

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What is a good process for testing antenna systems?

Initial measurement (static) should be made from BTS jumper connector into the antenna. If PIM products exist, break out last joint prior to vertical feeder rise and terminate with PIM LOAD. Carryout dynamic tests until PIM source is found and corrected. Measure from breakout joint into antenna. Carry out dynamic testing on main feeder run and tower top components until all PIM products have been exposed and fixed. Final static test in complete antenna system to prove all connections are good.

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Does the receiver port have a built-in high power termination capable of handling 40-80W and does the transmitting port also measure reflected PIM? Does the transmitting port have a built-in high power termination capable of handling reflected power of 40-80W?

The unit has only one 50 ohm port, which is transmit and receive. It transmits 2 carriers, each up to 40W and measures the resulting PIM generated in the antenna system under test, measures it in the receive band in the same port. Internally there is a very high spec duplexer to separate Tx from Rx. The port also measures return loss at the same time, and therefore you can see PIM measurement and RL on the same screen, to verify that you have a good 50 ohm connection. If there is a very bad match, and the power is reflected, the unit will handle this, but obviously this is not preferred for your test nor the unit. The accessories kit contains a 50 ohm low PIM test load which is capable of handling the total of 80W (2 x 40W) amount of power. Check out more technical info on PIM test equipment.

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Related links:
Passive intermodulation
PIM test
PIM test equipment units


Downloads:
Application Note - Anritsu
Certified Training Course - Anritsu
PIM Master Brochure - Anritsu
PiMPro Brochure - CCI
White Paper - Demystifying PIM in Todays Wireless Networks - CCI
White Paper - Troubleshooting PIM - Anritsu

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