Assessment of Extending a Two-Port Calibration to a Multi-Port Microwave Scanner

This work evaluates a sub-calibration method for a multi-port microwave imaging scanner. This decreases the complexity of a conventional full n-port calibration, albeit inserting uncertainties. The approach involves a combined 2-port full standard calibration along with a multi-port extension. It addresses systematic errors and reduces the impact of losses and phase shifts introduced by the multiplexing component of a microwave scanner, normally interfacing the 2-port transceiving stage with the multiple radiating elements. The analysis examines the calibration assumptions and validates them on a microwave scanner utilizing a 2-port vector network analyzer and a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2\times 22$</tex> solid-state switching matrix. Repeatability and stability tests confirm the calibration's reliability, effectiveness, and permissible effect on the imaging retrieval capabilities.