Co-Design of Tapering and Dielectric Loading for Minimizing the Scattering Cross Section of a Near-Field Measurement Probe

This paper investigates the antenna capabilities of a near-field measurement probe, such as the return loss (S11), radiation pattern and peak gain. For this purpose, a rectangular open ended waveguide (OEWG) is used, while minimizing its scattering cross section (SCS), to increase the accuracy of near-field measurements. In this context, the relation between tapering and dielectric loading of the measurement probe is analyzed, since the taper is simultaneously utilized as an air to dielectric transition for the antenna. Furthermore, absorbers are used around the opening of the OEWG, to reduce the SCS even further. It is shown, that the tapering and dielectric loading of the measurement probe are highly correlated and significantly influence the antenna capabilities. Finally, the best constellations to reduce the SCS and increase the antenna capabilities of a rectangular OEWG are shown with improvements up to 15 dBsm.