Broadband Microwave Near‐Field Imaging by Localized Field Perturbations

Inverted scanning microwave microscopy (iSMM), as a novel near‐field characterization tool, demonstrates unique advantages in research fields such as biomedicine and the dielectric properties of two‐dimensional materials. This paper proposes a dual‐port inverted scanning imaging method based on the perturbation of the spatial microwave field in microstrip lines by an uncoated silicon tip. Combining microwave vector network analysis techniques, a non‐invasive silicon tip scans the surface of samples above the microstrip line to obtain local S 11 and S 21 scattering parameters. Theoretical modeling and experiments validate the broadband resonant characteristics of the microstrip structure across the 1–10 GHz frequency range. Near‐field images of dried mouse fibroblasts were successfully acquired at selected frequencies (3, 5, and 8 GHz), revealing their distinct electromagnetic responses at different frequencies. Comparison of the signal‐to‐noise ratios (SNR) for S 11 and S 21 parameters indicates that the S 21 SNR exhibits more stable fluctuations (30–60 dB) across the 1–10 GHz range. This testing method possesses broadband microwave imaging capabilities, providing a reliable technical foundation for structural characterization studies in fields such as microelectronic devices, biological tissues, and functional materials.