MSCAN-a microwave field scanning system

A description is given of MSCAN (Microwave SCANning), a computer-controlled system designed to measure electric and magnetic fields in a liquid ambient medium. A two-axis positioning system moves a probe antenna, and the probe´s output signal is measured by a Hewlett-Packard 8410B automatic network analyzer. The fields are normalized to a selected reference point. An analysis of the quantization error in the HP8410B has been made in order to estimate a bound on the accuracy of the system. MSCAN has been used to measure the normalized electric field radiated by an open-ended dielectric-filled waveguide antenna in a water ambient medium at approximately 3 GHz. Normalized scattered fields, found from the difference between total and incident fields, were measured from a dielectric cylinder. However, the results were poor when fields were weak compared to the noise floor of the HP8410B. The problems involved in performing such measurements are discussed