This paper considers passive intermodulation (PIM) effects occurring in passive RF devices like mobile communication antennas where two or more high-power signals can simultaneously be present in the transmitter-receiver path. Due to nonlinear properties of the passive parts, the unwanted PIM components with combination of carrier frequencies may fall within the receive band. In this paper, the main causes of PIM are briefly reviewed. A description of the measurement procedure for testing the PIM performance is presented. In addition, a comparison between the PIM properties of five commercially produced antennas is performed in the GSM 900 frequency region.
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