SCIENTIA SINICA Informationis, Volume 51 , Issue 8 : 1316(2021) https://doi.org/10.1360/SSI-2020-0069

Analysis of passive intermodulation distortion caused by loose electrical contact

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  • ReceivedMar 23, 2020
  • AcceptedJul 21, 2020
  • PublishedAug 2, 2021


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本文的理论研究以及实验开展得到美国密苏里科技大学电磁兼容实验室(EMC Lab, Missouri University of Science and Technology)的 J. Fan 教授、David Pommerenke 教授、王彦盛博士, Apple公司杨森博士以及新加坡南洋理工大学张艺明博士的大力支持和帮助, 在此一并感谢


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  • Figure 1

    Generation of passive intermodulation

  • Figure 2

    (Color online) Loose contact model of coaxial connectors. (a) A couple of coaxial connectors; (b) schematic diagram ofcoaxial connectors; (c) illustrations of the loose contact

  • Figure 3

    (Color online) Contact mechanism model for the coaxial connector. (a) Micro-structure for the contact surface; (b) illustrations for the MIM and MM contacts

  • Figure 4

    (Color online) Equivalent circuit model of tight contact

  • Figure 5

    (Color online) The static model of loose contact. (a) The changes of loose contact; (b) the current paths of loose contact

  • Figure 6

    (Color online) Dynamic model of loose contact

  • Figure 7

    (Color online) Simulation model of loose contact

  • Figure 8

    (Color online) Simulation results for (a) the contact impedance and (b) the surface current density

  • Figure 9

    (Color online) Equivalent circuit model of loose contact

  • Figure 10

    (Color online) Experimental setup for the PIM measurement

  • Table 1   PIM analysis of China mobile GSM900 and other 2G systems
    (China Mobile)(China Telcom)(China Mobile)(China Unicom)
    Bandwidth of the receiver (MHz)935$\sim$954870$\sim$880935$\sim$954954$\sim$960
    The 3rd order PIM (MHz)871$\sim$928815$\sim$845871$\sim$928903$\sim$921
    The 5th order PIM (MHz)852$\sim$947805$\sim$855852$\sim$947897$\sim$927
    The 7th order PIM (MHz)833$\sim$966795$\sim$865833$\sim$966891$\sim$933


  • Table 2   PIM values of the SMA coaxial connector with different input power cases
    Input power (dBm)
    Results of the first test (dBm)$-$121$-$114$-$107$-$102$-$98$-$93$-$88$-$80$-$62
    Results of the second test (dBm)$-$118$-$116$-$105$-$101$-$95$-$93$-$85$-$79$-$65


  • Table 3   The relationship between the skin depth and frequency of alminum
    Frequency (Hz)
    Skin depth (mm)2.590.820.2590.0820.02590.00820.00259

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