In November 2020, Andrew VK3CV / WQ1S and Karl VK3LN made a contact in a previously un-explored section of the upper electromagnetic spectrum at 30 Terahertz (THz) which is 30,000 GHz.
A two way contact over 60 metres distance was achieved with 5×5 signals received each way. The contact is believed to be the first ever in this band anywhere in the world.
More read here: http://www.ok2kkw.com/30thz/new_30thz_band_used_for_hamradio.pdf
Thank you OK1TEH Matej for the info!
Picture: from screenshot