Click for Complete Site Directory
Latest RDF News Headlines
Complete results and lots of photos of the 2015 USA and IARU Region 2 ARDF Championships in Colorado are now in this site. It all took place August 27-30 in a beautiful 3300-acre Scout ranch at elevation of 7000 feet. Events included classic two-meter and eighty-meter competitions plus sprints and foxoring. Optional training sessions were August 24-26, just prior to the championships. Details are in the Event Information Page. USA's ARDF Championships are open to all. Visiting competitors from outside USA are welcome. Some of USA's medal winners will be invited to compete on Team USA at the ARDF World Championships in Bulgaria next September. If your club is interested in having a future USA Championships in your own area, here is information about hosting.
ARDF fans in the USA have been invited to participate in the 2015 China International ARDF Championships, which will take place in the city of Guangzhou in Guangdong Province of south China from December 3 through 9. These championships are being organized by the Guangdong ARDF Radiosports Club (GARC). There will be one day of unofficial training, followed on successive days by 80-meter classic, sprint, two-meter classic and foxoring competitions. Awards will be presented in fifteen age/gender categories. More information is here in this site.
Results and photos of the southern California on-foot transmitter hunting session at Angel's Gate Park in San Pedro on Sunday, September 13, 2015 are now in this site. This session was part of the ARRL Southwestern Division Convention (HamCon) and was co-sponsored by the Fullerton Radio Club and the Ft. MacArthur Military Museum. The next southern California session will be announced soon. For earliest notification of future sessions, join the southern California ARDF mailing list. If you live elsewhere, click to get contacts for other North America ARDF sessions. This Homing In site also has results and photos of previous southern California radio-orienteering events including May 16 at Hillcrest Park in Fullerton.
In the August 2015 issue of CQ Amateur Radio Magazine, my Homing In column recounts the story of a Scout Venturing Extravaganza last year in Colorado that featured ham radio transitter hunting. The Scout Ranch where that Venturing event took place is the site of this year's USA and IARU Region 2 ARDF Championships. Some ham radio stores may still have the April 2015 issue of CQ Magazine, which feature more of the fun of hidden transmitter hunting for youth, with tales of hunts at the Duluth Childrens Museum and at a Scout Jamboree-on-the-Air in San Pedro, California. My column on radio direction finding now appears in CQ Magazine four times per year. CQ Magazine is available in print by subscription and in Amateur Radio stores. You can also subscribe to CQ in digital form, viewable on PC, Mac, iPad, iPhone and Android. I welcome your input for future articles and columns, so please continue to send me your news of mobile and on-foot transmitter hunt activities.
New apps for Apple and Android tablets and phones can simplify bearing plotting and triangulation over short and long distances. They are useful for both on-foot and mobile transmitter hunting. Bearings can be entered manually or with the internal device compass. Some apps allow entering bearings taken by other hunters or networing with them during the hunt. Read all about Foxhunt Pro, SigTrax and Map-n-Compass apps in this sample Homing In column from last year.
What to see what radio-orienteering is like "up close and personal?" Our Russian friends have published an outstanding high-definition video with footage from the ARDF World Championships and other international competitions. See if you can pick out Team USA and its members in these scenes. After you view the radio athletes in action, come back to this Homing In site to find out more about ARDF rules and the stateside events that you can attend.
The seventeenth annual CQ Worldwide Foxhunting Weekend (CQ WW FW) was May 9-10, 2015 but if your club didn't hold a hunt then, it's not too late! Start the fun now by reading the announcement at this site and my articles in the March and April 2015 issues of CQ Magazine. After that, plan a mobile or on-foot hunt for a weekend in the near future. This annual event is an ideal time for ham clubs and non-club groups around the country to enjoy this fast-growing sport. For clubs that participated in this year's CQ WW FW, the next thing to do (besides planning another hunt, of course) is send the results and photos to me for the follow-up article. Get the report form here.
USA medalled in the Seventeenth ARDF World Championships, which took place near Burabay, Kazakhstan from September 6 through 13, 2014. Vadim Afonkin KB1RLI took silver in M40 category in the two-meter competition on September 8. Kazakhstan Federation of Radiosport and Radioamateur (KFRR) hosted the championships, which included formal competitions on two meters and 80 meters, plus sprints and foxoring. Each country may have up to three persons per age/gender category on its team. Team USA positions were filled based on performance in the 2013 and 2014 USA ARDF Championships. More information and links to results are in this Homing In site.
Obtain RDF equipment for two-meter hunting on foot
Attend a southern California on-foot transmitter hunt
Participate in national and world championship hunts
Learn about mobile transmitter hunting (T-Hunting) and the equipment that hunters use
Attend a southern California two-meter mobile T-hunt
Buy or build a two-meter "fox" transmitter
Learn about 80-meter transmitter hunting
The Southern California T-Hunts for Beginners page has has information about three monthly mobile hidden transmitter hunts in the Orange County area where first-timers are especially welcomed and encouraged. On two of them, there are usually some clues to help everyone eventually find the transmitter and on one, you can compare bearings with other hunters on a separate frequency. Mount some RDF gear on your vehicle and come on out!
Mobile hidden transmitter hunters have regularly prowled the streets in search of the elusive sources of unusual signals for more than four decades. Equipment has evolved, but the adventure and intrigue remain the same. Read "T-Hunting Then and Now -- From Gooney Birds to GPS" in this site for stories of classic mobile T-hunts in the Los Angeles area. Some of them, but not all, could be done again today. Then to find out what it's like nowadays, and to help get your club started in this activity, read "Transmitter Hunting, Southern California Style."
When it's your turn to hide the transmitter, what will you use? It depends on the range and duration of the hunt, as well as whether or not the transmitter must be unattended and automatic. It's important to match your foxbox and its location to the level of proficiency of the hunters. There are many options, and you can read about them in the Foxboxes for Mobile and On-foot Transmitter Hunts page in this site.
For three decades, international-rules radio-orienteering competitions have had two major competition days. Each participant must compete on the two-meter band and the 80-meter band. The 2012 USA and World ARDF Championships included competitions in two new events: sprints and foxoring. The sprint is a shortened form of the five-fox 80-meter ARDF run that's intended to be a demonstration for the public. Foxoring is a combination of classic orienteering and direction-finding on 80 meters. More information about these new events can be found here.
For over ten years, I have used a special cubical quad for mobile transmitter hunting on two meters. From inside the vehicle, I can select the signal polarization. Find out why this is important, why I like this antenna and how to make one for yourself in a classic Homing In column titled "Build a Multiple-Polarization Quad."
The Agrelo DFjr Doppler RDF set has been out of production for over ten years, but there is still a great deal of interest in it. DFjr was the first inexpensive plug-and-play Doppler set designed for interface to computer mapping systems and APRS. For those who own one or are considering buying a used one, the DFjr page on this site has a downloadable manual, my 73 Magazine review, antenna system improvements, and frequently asked questions about this product.
What's "Homing In?"
Homing In refers to the process of tracking down the source of a radio or other electromagnetic signal using radio direction finding (RDF) equipment.
Homing In is also the title of my regular column on RDF that ran for 15 years in 73 Amateur Radio Today magazine, then for ten years in CQ-VHF magazine and now appears quarterly in CQ-Plus digital magazine. At this Homing In site, you will find more about these columns, plus RDF articles that I have written for other publications, including Monitoring Times, CQ VHF and QST magazines. There is also information about my comprehensive book on the subject.
Radio direction finding is used to find sources of interference to any form of wireless electronic communications, including broadcast and two-way radio, television, and telephones. It is also used to track missing or stolen cars and other property. Search and rescue workers use it to find persons in distress. Emergency Locator Transmitters in downed aircraft are tracked with RDF techniques.
Most of the information at this site pertains to RDF equipment and techniques for Amateur Radio (ham) operators. Hams use RDF to track jamming stations and stolen equipment, but more often, they use it just for fun. Hidden transmitter hunting has been done by hams for about fifty years and it is a growing activity. T-hunting refers specifically to hunts involving hams driving in RDF-equipped vehicles. A mobile T-hunt is best described as hide-and-seek for all ages with radio gear. When you set out on a T-hunt, you never know where you'll end up, and you have no idea what you're going to find. No form of ham radio contesting is more fun! Mobile T-hunting is done in cities and towns all over the USA, and elsewhere in the world. Depending on the frequency band and the nature of the hunt, the hunters use loop, yagi, quad, doppler and time-difference-of-arrival RDF antenna systems mounted on their vehicles. Click here for for general information about mobile T-hunting or click here for beginner-level T-hunts in southern California.
Mobile T-hunting is called foxhunting in some parts of the USA, but everywhere else in the world, the terms "foxhunting" and ARDF refer to another kind of RDF contest, done completely on foot in large woods and parks. It's a map-and-compass sport similar to orienteering, with about a half-dozen "fox" transmitters to find in a period of two hours or so. Someday this sport, which is also called foxtailing, fox-teering and radio-orienteering, may become an Olympic event. Meanwhile, it's a fun-filled activity for your hamfests and Scout Jamborees. Try it, and you may find yourself at the next annual national USA ARDF Championships. You might even become a member of ARDF Team USA, which has competed in five foxhunting World Championships. Click here for for general information about radio-orienteering or click here for beginner-level ARDF events in southern California.
Keep reading---you will find lots more about foxhunting, T-hunting, and other uses of RDF at this site.
What's at the Homing In Site?
Find your topic of interest below in the complete Table of Contents (or as some call it, the Site Map). Or you can Click here for the Site Search page.
Getting Started -- The basics
RDF Topics in Print -- Read all about it
Home-built RDF Projects -- Inexpensive and educational
Commercial RDF Equipment -- Getting the most from it
Follow-up and Support -- for readers of THRDFS and Homing In
Championship Radiosports -- Taking on the world
Results, stories and photos of ARDF sessions, large and small
Volunteer Opportunities -- Use your RDF skills to help researchers and protect wildlife
Spending a few minutes at this Homing In site will give you a jump-start into the world of transmitter hunting. After that, you can find out how to get involved in mobile T-hunts in your area by visiting local T-hunt/foxhunt web sites and contacting nearby Homing In Correspondents listed on the links page. You'll find manufacturers and suppliers of RDF gear there, too.
Who is KØOV?A registered professional electronic engineer and an active Amateur Radio enthusiast since age 11, Joe Moell KØOV has over 45 years of experience designing radio-frequency circuits and systems for broadcast, communications, and radar, ranging from near-DC through microwave frequencies. He has designed new devices for radio direction finding and has written about RDF and other topics for almost every ham radio publication in the USA. In February 1998, he was appointed by the American Radio Relay League (ARRL) as the USA's first ARDF Coordinator, to promote international-style foxhunting and to organize Team USA for international ARDF competitions. He also conducts the annual CQ Worldwide Foxhunting Weekend.
Joe collaborated with Tom Curlee WB6UZZ to write TRANSMITTER HUNTING---Radio Direction Finding Simplified, a comprehensive text on RDF, and has written over 230 published articles on the subject, including his monthly Homing In columns that ran for 15 years in 73 Amateur Radio Today magazine, then for ten years in CQ-VHF magazine, for one year in CQ-Plus digital magazine and now appears four times per hear in CQ Magazine. As a Technical Advisor to ARRL Headquarters, he authored a new chapter on RDF for The ARRL Handbook and has made more than 100 presentations on transmitter hunting to clubs, conventions, classes and seminars. As time permits, he is available for private engineering consulting.
Joe and April (WA6OPS) Moell are graduates of the University of Nebraska. They have served as Course Marshals and Jurors at international foxhunting championships. When not participating in transmitter hunts or writing about it, they teach ham radio licensing courses and help support the emergency communications needs of the hospitals in their county.
Although not about RDF, another great ham place to browse is the Hospital Disaster Support Communications System (HDSCS) site. There you will learn how volunteer Amateur Radio operators can be an important backup communications resource for hospitals, if the hams are well organized and trained. The eighty members of the HDSCS in Orange County, California have served over 34 hospitals in over 120 communications emergencies during the past 35 years. We have rapidly responded following earthquakes, wildfires, floods, power outages and internal switchboard failures. If you think that your local ARES® or RACES group is presently serving all of the disaster communications needs of your community, you may consider taking on a new mission after seeing this site.
Surfing suggestion: For a quick start into the world of RDF and mobile hidden transmitter hunting, jump to Let's Go T-Hunting.
Please note that this Web site is built and maintained independently by Joe Moell. It is not sponsored by or affiliated with CQ Publications, 73 Amateur Radio Today, Wayne Green Enterprises, TAB/McGraw-Hill, ARRL, or any other commercial or non-commercial entity. All content is protected by applicable intellectual property laws.
Entire site Copyright © 1996-2015 Joseph D. Moell. Text, photos and original graphics may not be served or reproduced elsewhere without permission.
PO Box 2508
Fullerton, CA 92837
This page updated 25 September 2015