An antenna consisting of a pair of horizontally spaced vertical elements connected, or coupled, differentially to a single output circuit and designed to minimise the response to the horizontally polarized electric component of the field, the response pattern having the shape of a figure of eight.
Reference: B.S. (modified)
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
Centre of buoyancy
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM