Recent Progress with a Near-Field Scanning Microwave Microscope
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This poster gives an update of progress on developments on a Near-Field Scanning Microwave Microscope (NSMM). This instrument enables surface measurements of complex permittivity at micron scales by scanning a tungsten tip which is coupled to a resonant cavity.
Changes in the complex permittivity at the surface result in small shifts in the resonant frequency of the cavity, and small changes in Q-factor which are measured with a Vector Network Analyser. The separation between tip and sample is maintained to ~10 nanometres using a tuning-fork system and a servo loop.
Recent work has aimed to overcome three main challenges associated with the instrument: (i) techniques for reliable manufacture of the delicate tuning fork assemblies, (ii) finding materials that are suitable for use as lossy reference standards that are uniform on a small scale, and (iii) development of calibration and computational procedures to improve accuracy and traceability of measurements of complex permittivity. These aspects will be discussed in this poster.
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