1. Introduction to Radio Direction Finding
Tom Wheeler NØGSG
Bill Brinker WAØCBW

2. Radio Direction Finding (Foxhunting)
The science and art of locating hidden transmitters
Very handy when interfering signals must be tracked.
Skills could be livesaving when tracking a lost person!

3. Low and High Tech
You do not need expensive equipment to successfully locate transmitters.
You do need practice!
“Low tech” methods usually involve some “dead reckoning” skills, combined with careful observation of terrain and signal level.
“High tech” methods use specialized equipment.

4. Low Tech Relies on knowledge of terrain and signal propagation.
May use directional antenna, or when close to fox, a very short bit of wire.
Practice is essential!

5. Low Tech Directional Antennas Body Shielding with Portable Radio
These methods rely on signal strength. You MUST think about the impact of terrain on the radio signal.
Body shielding is NOT a reliable indicator for bearings over variable terrain.

6. Think Terrain

7. Determining a Fix

8. Low Tech – Body Shielding
Antenna Stub
If the signal is too strong, use a stub antenna. If it’s STILL too strong, tune +/- 5 kHz off frequency.

9. Low Tech Directional Antenna
You may need an RF attenuator if the receiver swamps.
Something critical is missing from this antenna – what is it?

10. High Tech Methods Doppler GPS Hand-Held and Mobile Units
Practice is still important!

11. Mobile Doppler Doppler GPS Hand-Held and Mobile Units
Practice is still important!

12. Mobile Doppler Operation

13. Mobile Doppler Scanning Signal Antenna Unit Recovered Audio
FM Receiver

14. Hand-Held Doppler

15. Tips for Radio Direction Finding
Safety always comes first.
Always be aware of your surroundings and think of how they might affect a radio signal. High ground usually means cleaner bearings to the RF source.
Be methodical in your search; use a map if available. If team searches in group, use a uniform system for reporting bearing data.

16. Question and Answer