A unidirectional radio direction finder is a device used to locate the direction of a radio signal. It is commonly used in navigation and communication systems. There are alternative terms for unidirectional radio direction finder that can be used interchangeably. Some common synonyms include RDF, Radio Compass, Radio Bearing Indicator, Directional Radio Beacon, Radio Direction Finder, and Direction Finding. These devices function in a unidirectional manner, meaning they receive signals only from a specific direction. They are essential tools in aerial, marine, and land navigation, helping pilots, sailors, and hikers to determine their location and navigate with greater precision. Regardless of the terminology used, they remain an essential part of any navigation system.