Definition of "direction finder" []

• A device for determining the source of a transmitted signal, consisting mainly of a radio receiver and a coiled rotating antenna. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Station CAST obtained a radio direction finder bearing on a Yamamoto radio call sign of YO WI ØØ on December 2."
• "Between 8:05 A.M. and noon, Station H radio operators and direction finder experts intercepted radio dispatches that clearly placed the First Air Fleet north of Oahu."