This article reports on an extensive interlaboratory comparison of measurements of material properties between 2 GHz and 1 THz using both vector network analyzer (VNA)-based and optical-based methods. For the former, techniques including open resonators, conventional free-space quasioptical systems, and a relatively new guided free-space approach through use of material characterization kits (MCKs) were utilized. The optical-based methods included both time-domain spectroscopy (TDS) and frequency-domain spectroscopy (FDS). Measurement setups for these five techniques located at five well-established laboratories have been employed in the measurements of seven types of commonly used dielectric materials. The results of the measurements by the participating laboratories using each of these techniques were compared to assess levels of agreement between the utilized techniques and thereby establish confidence in the characterizations of each material. Measurement results of these seven materials are presented, together with detailed discussion. This is the first time that an interlaboratory measurement comparison of material properties has been conducted over nearly three decades of frequency and involving such a range of techniques. This work should prove beneficial to applications where material properties need to be known accurately in the microwave to terahertz region.

The project (18SIB09 TEMMT) has received funding from the EMPIR programme co-financed by the Participating States and from the European Union's Horizon 2020 research and innovation programme. The project (23IND10 OnMicro) has received funding from the European Partnership on Metrology, co-financed from the European Union’s Horizon Europe Research and Innovation Programme and by the Participating States. Funder name: European Partnership on Metrology. Funder ID: 10.13039/100019599. Grant number: Partnership 23IND10 OnMicro.