Passive Intermodulation (PIM)
Basically, the device is acting like a frequency mixer with a local oscillator (LO) and RF input. All of the spurious mixing products are generated (±j*f1 ± k*f2); however, most are either at levels too low to be detected or are far enough out of the band of interest to be of any consequence. 3rd-order products (2*f1 - f2, and 2*f2 - f1) are generally the most troublesome since the are most likely to fall inband and at higher levels (levels generally decrease as the product order increases).
If a PIM is generated from a transmitter channel that falls within an adjacent receiver channel, desensitization will occur. A typical PIM requirement is -110 dBc or more. Many vendors offer RF cables with PIM specifications of -140 dBc.
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