Probe-Free High-Resolution Millimeter-Wave Frequency-Diverse Sensing Based on Spoof Surface Plasmon Polaritons

This communication proposes a near-field millimeter-wave (mmWave) frequency-diverse sensing system based on a spoof surface plasmon polariton (SSPP) transmission line. SSPP structure features high-dispersion field distribution along the line, greatly enhancing the sensing capacity within the specified frequency band. A probe-free retrieval approach is proposed to build the measurement matrix based on a small number of designed tests instead of probing the field distribution. Such a probe-free approach does not require experimentally probing field distribution which may bring errors to the measured field due to the perturbation of probes, and hence greatly improves the accuracy of the measurement matrix and, therefore, the sensing resolution. This is especially useful at mmWave frequencies where probe perturbation is relatively strong in field measurement. As an illustrative example, we recovered a measurement matrix of 1001 spatial pixels by making only 20 tests using a known object at different known positions. The pixel resolution has reached <inline-formula> <tex-math notation="LaTeX">$\lambda /100$ </tex-math></inline-formula>. And using this measurement matrix, we are able to accurately sense the position of a copper strip with a sensing error of 0.1 mm (about <inline-formula> <tex-math notation="LaTeX">$\lambda /50$ </tex-math></inline-formula>).