In the U.S. and Canada, the plural of the noun antenna is antennae when the word denotes the flexible sensory appendages on insects and other animals. But when the word refers to a metallic apparatus for sending or receiving electromagnetic signals, American and Canadian writers usually use antennas.
British writers tend to use antennae for both purposes.
Australian and New Zealand writers are split on the matter, using both plurals for the metallic devices.
And you: how do you say the plural of antenna?