Analysis and measurement of antenna passive intermodulation

The passive intermodulation (PIM) interference caused by antenna nonlinearity has a serious impact on the performance of the high power multi-frequency communication system, especially when the antenna is shared by the transmitter and the receiver at the same time. Theoretical analysis on the PIM was first discussed in this paper, and then the designed measurement system was introduced. The testing experiment was carried out on the antennas of a special communication system under various conditions. The main factors causing PIM was discussed through analysis on the acquired data. The result also shows that the PIM measurement system serves as a reliable tool to predict whether an antenna has an accepted PIM level in actual communication system or not.