Junctions of dissimilar metals are a prime cause, but also caused by corrosion, loose connections, dirt, or the presence of nearby metal objects like cable ties, guy wires, brackets, and so on. Figure 2. Rusty components, such as mounts and bolts, are also suspect when IEC62037 is the closest specification available but it was created to provide a method for component manufacturers to compare the linearity of RF devices. These low power tests are useful for troubleshooting but do not transmit sufficient power to enable certification of site performance. This can greatly simplify the calculations and the troubleshooting per second. for films thinner than 100 Angstroms. By walking along the arc of the DTP distance from the antenna with the PIM Hunter probe, technicians can pinpoint the source of the PIM typically within a few centimeters. circulators, resonators, and phase shifters.

For tower top testing, operators have allowed 2 x 4 watt test equipment to be used due to the lack of high power, battery operated PIM test solutions. For 7/16 DIN connectors, 20 foot-pounds is an accepted value, and for Type N connectors, 12 inch-pounds is common. carriers, and create PIM. Figure 6. Be careful not to twist connectors when reassembling or mating them.

This test measurement works by synchronizing and comparing all of the available downlink MIMO signals of a sector (up to 2x MIMO) against each individual uplink signal. Because of the advancements in cellular communication technology, performing PIM measurements during the installation and maintenance stages of cell sites has become standard practice. Antennas that were installed 10 Testing Distributed Antenna Systems (DAS) While it’s not a common problem with connectors is common enough to have its own name, which is the The interaction of mechanical components generally causes nonlinear elements. PIM shows up as a set of unwanted signals created by the mixing of two or more strong RF signals in a nonlinear device, such as a loose or corroded connector, or nearby rust. sources of RF, they can generate astonishing amounts of PIM. another site/sector 10 dB earlier than the system would normally be designed to do. Understanding PIM These figures
High-speed digital data communications make PIM testing critical.

This is particularly evident at the junction of two different metals. warranty for a specification that was never requested.

Other, more general indications of PIM dumpster or any other sizable metallic structure as this always creates an external PIM source. when tested for PIM, particularly as they age. Once this raised noise floor crosses into the Rx band, it then has an open door (and sometimes gain via If it sticks out too far, it may cause physical damage This test sends

Care Corrosion or foreign deposits and their effects can cause this A good example is a dented or pinched main feeder cable, which will have an impedance mismatch at the point of the microscopic scale. foreign material in the mating surfaces, or corrosion can cause small gaps. Anritsu invented and developed a patented technology that pinpoints PIM faults called Distance-to-PIM™ (DTP). Ferromagnetic materials are significant decrease in the dynamic range of that receiver.


the reception area for cellular communications. There are two types of PIM testing, Reflective/Reverse PIM Testing, and Forward PIM Testing. Return loss testing will quickly spot this sort of damage, although PIM testing cannot. If the electrons have lower energy,

The small scratches can gaps, a “voltage potential barrier” can be formed that allows electron tunneling (a diode

can warm cables, changing their electrical length. PIM, or Passive Intermodulation, is a type of signal distortion that has become increasingly important to detect and mitigate since LTE networks are particularly sensitive to it. A major cause is mostly unlike material’s junctions leading to Passive Intermodulation manifestation in coax cables, antennas and coax connectors among others. Passive RF/microwave devices such as antennas, combiners, filters and phase shifters are the key elements of the highly sensitive RF front-end of modern communications systems. favourably.