In this paper, we describe how to define and build a set of known loads to be used in near-field microwave microscopy. Such loads are necessary to set up a microwave calibration kit, enabling local quantitative measurements by the microscope. The proposed protocol is validated through the microscopy system we have recently developed that combines a scanning tunneling microscope and a 70-GHz vector network analyzer.

Microwave microscopy has recently attracted intensive effort, owing to its capability to provide quantitative information about the local composition and the electromagnetic response of a sample. Nonetheless, the interpretation of microwave images remains a challenge as the electromagnetic waves interact with the sample and the surrounding in a multitude of ways following different paths: microwave images are a convolution of all contributions. In this work we show that examining the time evolution of the electromagnetic waves allows us to disentangle each contribution, providing images with striking quality and unexplored scenarios for near-field microscopy.

A short-open calibration (SOC) technique for deembedding structures with an arbitrary, possibly coupled, number of ports is introduced in this paper. While deembedding algorithms used in commercial software packages require the analysis of two "standard" structures for each set of ports, the proposed solution requires only one standard to be analyzed, with a significant reduction in the overall computation time. Moreover, unlike other deembedding techniques, the SOC technique does not rely on specific assumptions about the nature of the port discontinuities and of the feeding lines. This fact circumvents ambiguities linked to the definition of the characteristic impedance when hybrid modes are involved. Implementation-ready formulas are provided.

In this work, we introduce a hybrid atomic-force/near-field scanning microwave microscope, exploiting the tomographic capabilities of the microwave microscopy to explore structures of relevant interest, namely, samples involving both biological and non-biological materials at the same time. In particular, we show imaging of C2C12 muscle cells grown in the presence of bundles of multi-walled carbon nanotubes: here, the microwave microscopy, by virtue of its tomographic potentiality, highlights how cells incorporate some nanotubes in their fibers.

In this work, we demonstrate a hybrid scanning tunneling microscope/near field scanning microwave microscope featuring nanometric resolution in liquid environment. The system performs an ultra-broadband microwave analysis, since the frequency is swept (up to 50 GHz) for each spatial point of the sample under measurement. A conversion in time-domain allows to disentangle near-field and far-field probe-sample interactions. Results are reported for highly oriented pyrolitic graphite immersed in water, and demonstrate microwave nanometric resolution in spite of the presence of the losses induced by the aqueous environment.