'Antrum' (i) was a British operation by the Special Operations Executive to establish radio contact and develop resistance groups in the Ålesund area of German-occupied Norway (5 December 1941/March 1942).

A three-man Norwegian party (F. Aaraas, K. J. Aarsæther and K. Aarsæther) was delivered by sea, and Aaraas then trained a local radio operator before returning to the UK in January 1942. K. J. Aarsæther also returned in January and was replaced by his brother Knut, who returned to the UK in March.