Improvements on calibration measurements with a Martin–Puplett interferometer

We describe a simple and efficient improvement to the Martin–Puplett interferometer, built at the Max-Planck Institute for Radioastronomy in Bonn. Interferograms with its corresponding spectra taken with the interferometer operating in the vacuum mode, have confirmed that the detector’s signal increases up to ∼10% when the microwave foam absorbers used as radiation sources are replaced by blackbody cavities.