Minimized standing waves in microwave radiometer balancing calibration

We report on investigations of the reflective properties of reference loads used for the balancing calibration of a water vapor radiometer at 22 GHz. Besides the commonly used egg‐shaped ECCOSORB® CV3, a set of different absorbers in different orientations with respect to the reference beam was investigated. Our measurements show that the commonly used material and the common orientation of the reference load are not optimal, and we present a better solution that minimizes baseline artifacts.