A Microwave Near-field 3D Super-resolution Imaging Method

Microwave imaging is widely used in many areas involving non-destructive testing, biomedical imaging, radar detection and imaging, etc. However, there is a lack of microwave 3D imaging methods with lateral and depth super-resolution. We propose a microwave near-field 3D super-resolution imaging method based on the near-field scanning microwave microscopy (NSMM) technique, enabling lateral and depth super-resolution simultaneously. A resonant-cavity probe is designed to scan the first group of step samples to establish a linear equation between the phase of the normalized reflection coefficient (NS11) and the tip-sample distance ( $$\Delta H$$ ). The second group of samples is scanned at the resonance frequencies corresponding to $$\Delta H$$ , realizing the layer-by-layer imaging of the letter patterns. Finally, we have calculated the height information through the fitted linear equation and reconstructed the second group of step samples with letter patterns. The 3D reconstruction of the second group of step samples with letter patterns is completed. The depth variation of the step and the height of the letter patterns are 200 $$\mu m$$ (~ λ/570), which can be identified approximatively through experiments. And the letter patterns with a lateral width of 720 $$\mu m$$ (~ λ/160) are resolved. The experimental results show that our method has good feasibility in realizing microwave 3D imaging with depth and lateral super-resolution.