  Sub-Terahertz (THz) frequencies between 100 GHz and 300 GHz are being
considered as a key enabler for the sixth-generation (6G) wireless
communications due to the vast amounts of unused spectrum. The 3rd Generation
Partnership Project (3GPP) included the indoor industrial environments as a
scenario of interest since Release 15. This paper presents recent sub-THz
channel measurements using directional horn antennas of 27 dBi gain at 142 GHz
in a factory building, which hosts equipment manufacturing startups.
Directional measurements with co-polarized and cross-polarized antenna
configurations were conducted over distances from 6 to 40 meters.
Omnidirectional and directional path loss with two antenna polarization
configurations produce the gross cross-polarization discrimination (XPD) with a
mean of 27.7 dB, which suggests that dual-polarized antenna arrays can provide
good multiplexing gain for sub-THz wireless systems. The measured power delay
profile and power angular spectrum show the maximum root mean square (RMS)
delay spread of 66.0 nanoseconds and the maximum RMS angular spread of 103.7
degrees using a 30 dB threshold, indicating the factory scenario is a
rich-scattering environment due to a massive number of metal structures and
objects. This work will facilitate emerging sub-THz applications such as
super-resolution sensing and positioning for future smart factories.
