Waveguide Cell with Water Filling for Passive Intermodulation Localization on Planar Circuits

This work presents a novel miniaturized waveguide cell with water filling for passive intermodulation (PIM) localization on planar circuits. The planar circuit as printed circuit board (PCB) is excited in a small waveguide, while its PIM product is detected simultaneously. The waveguide width is minimized by water filling (high permittivity dielectric), and the localization resolution is enhanced. During test, the PCB only needs move through the waveguide twice, once along its $X$ -direction and once along its $Y$ -direction. By crossing the peak PIM distribution line along two directions together, the regions on PCB have PIM responses that can be decided. The proposed method is intended for the planer PCB and other normal PCB with surface mount components.