Microwave analog to light scattering measurements: A modern implementation of a proven method to achieve precise control

The experimental determination of scattered electromagnetic radiation from a known target illuminated by a known source remains an essential tool to test new scattering theories and to investigate the scattering by particles for which a theory has not yet been devised. This article describes a modern broad-band microwave scattering facility capable of determining the elements of the scattering matrix from 0 to 168 degrees scattering angle under automated control. The laboratory measurements can cover the size range from near the Rayleigh limit to geometric optics. Both phase and intensity are routinely measured at 85-501 discrete wavelengths from 2.7 to 4 mm, which allows the derivation of all elements in the scattering matrix. The unwanted background radiation can be removed through vector subtraction and the result verified using the technique of ''time-gating'' based on inverse Fourier transformation and time domain analysis. Measurements are shown to be repeatable and accurate. This is primarily due to the use of a ''clean'' mechanical and electronic design in combination with high mechanical and thermal stability.