A passive intermodulation(PIM)model based on electrothermal coupling effect is proposed to address the problem that current PIM model cannot explain the PIM mechanism and describe the experimental rules accurately.This model is further verified experimentally by using a metal point contact structure.First,a near-field coupling PIM measurement method based on waveguide slot is established,which makes the device under test(DUT)separate with the test equipment.This method overcomes the restriction in tradition...