Development of Scanning Free-Space Measurement setup and its application to structural imaging.

Abstract

This paper proposes a scanning free-space measurement (SFSM) setup for the evaluation of microwave absorption properties of a structure. The system works by illuminating the specimen with microwave signals of varying frequencies and measuring the power of reflected microwaves. The
reflected power is then divided by the emitted power in order to convert the measurements to the standard parameter known as S11. The system comprises of a vector network analyzer (VNA) to measure S11 parameter, focused horn antenna attached to the VNA for transmitting/receiving
microwave signals, a dual-axis automated translation stage for raster scanning of the specimen and a standard personal computer. A graphical user interface (GUI) running on the computer manages the configuration and synchronization of the VNA and the stage system, S11 reception from VNA and compilation of results for display to the user. The GUI is created in C++ using Qt framework and Qt Widgets for Technical applications (QWT). It is designed with a minimalistic approach to promote usability and adaptability masking the intricacies of actual system operation.