A radio direction finder, or RDF, is a device for finding the direction to a radio source. Due to radio's ability to travel very long distances "over the horizon", it makes a particularly good navigation system for ships and aircraft that might be flying at a distance from land.
RDF's work by pointing a directional antenna in "various directions" and then listening for the direction in which the signal from a known station comes through most strongly. This sort of system was widely used in the 1930s and 1940s. RDF antennas are particularly easy to spot on German World War II aircraft, as loops under the rear section of the fuselage, whereas most US aircraft enclosed the antenna in a small teardrop-shaped fairing.
More on [ Radio direction finder ]

Homing In - All about hidden transmitter hunting and radio direction finding for radio amateurs. Links, and local contacts to help find RDF activities in your area.
Meta Description: [ All about hidden transmitter hunting and radio direction finding for radio amateurs. How it's done, what equipment is used, plus dozens of links and local contacts to help find RDF activities in your area. ]
Pictures - Fox hunting announcements, equipment, projects and links. Polar II setup information. Icom 706 mkII external S-meter installation. Pictures and antenna designs.
70 cm RDF for rockets - Describes a system on 70 cm freqencies to track and locate small rockets.
Amateur Radio Direction Finding Web Ring - Group for enthusiasts of Radio Direction Finding.
Meta Description: [ The web ring is for Amateur Radio Direction Finding and Fox Hunting Web sites.
The sites within this ring have information about Hams tracking radio transmitters for fun and to 'self police' the Am ]
ARDF Holland - Amateur Radio Direction Finding - Amateur Radio Direction Finding in the Netherlands, all about foxhunting
Meta Description: [ ARDF Holland, Information about ARDF activities in the Netherlands, in English and Dutch ]
BMG Engineering - Former supplier of the SuperDF. Tutorials and projects.
Build your own DF unit - Building your doppler, pictures and instructions.
Meta Description: [ Information to build a Ham amateur radio direction finder (doppler based) to use for locating radio transmitters ]
Hidden Transmitter Hunting - Pictures and plans for antennas, attenuators, aniffers, hiding equipment, and accessories.
N6QAB's Radio Direction Finding Web Page - Pictures and descriptions of Radio Direction Finding and Transmitter Hunting equipment.
Meta Description: [ Pictures and descriptions of Radio Direction Finding and Transmitter Hunting equipment. ]
NoBarc Hounds Amateur Radio Tansmitter hunters - Radio Direction finding for sport and emergencies.
Radio Orienteering in a Compact Area - On foot radio-orienteering, rules, projects, and event reports.
Radio Direction Finding Projects - A collection of useful and interesting projects for the RDF enthusiast by Joe Leggio, WB2HOL
Transmitter Hunting - Amateur radio direction finding, transmitter hunting, by triangulating a radio signals direction and plotting its bearing on a map. Hunters use Dopplers for tracking hidden transmitters anywhere in the San Francisco Bay Area.
Meta Description: [ Transmitter hunting a hidden radio beacon by triangulating the signal then tracking and locating its position. Radio direction finding, RDF, ARDF, DF, Foxhunt, t-hunt, are other names given to this radio location sport. www.thunt.org James Sakane, KD6DX. ]
VK3ZPF WEB SITE - VK3ZPF's amateur radio web pages including foxhunt projects
Meta Description: [ VK3ZPF's amateur radio web pages including foxhunt projects ]
WB6EYV Doppler DF - Describes a homebuilt mobile Doppler D/F unit, with theory, schematics, parts list, and all PC artwork.
Meta Description: [ Describes a homebuilt mobile Doppler D/F unit, with theory, schematics, parts list, and all PC artwork. ]
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