Chip-level calibration method using improved NFP and CPPs and MPs for the NFS standardization

Anew calibration method for the near-field scanning (NFS) system is presented. The proposed calibration method consists of a new near field probe (NFP), circular patch patterns (CPPs), and meander patterns (MPs). The proposed method improved spatial resolution and simplifying a calibration procedure for the NFP compared to the conventional method defined in IEC61967-3 and 6. Also, the effect of the NFP length on frequency response was investigated with lengths of 8 mm and 30 mm. We designed and fabricated CPPs of diameter (D) = 20, 40, 60, 100 mm and MPs of various widths and spaces. Thus, we found reverse relations between spatial resolutions and heights of measuring points with the simplified calibration procedure. The testing result shows that a spatial resolution of 120 µm a height of 200 µm was verified without complex correlation algorithms under 8 GHz. For manufacturing cost all patterns and the NFP were realized with low-cost fabrication using PCB (FR-4) not by a conventional LTCC process.