Natural Radio signals occur within the range of human nearing so no frequency conversion or demodulation is necessary. All that is necessary is to amplify the signal and convert it from a radio wave to audio so that it can be heard. At its simplest, a Natural Radio receiver is a high-gain audio amplifier with an antenna on the input and headphones or a speaker on the output.
(There are naturally occurring signals that extend above and especially below the range of human hearing, but the most common signals are within the range of our hearing.)
The only real complexity that needs be added to a receiver is low-pass filtering on the front end to prevent overloading by strong out-of-band signals, and some form of filtering to get rid of the annoying hum and buzz from power mains that plagues the Natural Radio listener.
Receivers are of two basic types: E-Field and H-Field.
Kits & Boards Available
Here are some sources for project boards and kits.
The INSPIRE project sells their VLF-3 receiver kits for $120. If you are interested, the website address is:
or contact them at: Info@TheINSPIREProject.org
Another source for boards of interest to the VLF and Natural Radio experimenter is Far Circuits. Far Circuits has produced circuit boards over the years for many construction projects appearing in QST, 73, and other electronics publications.
The listing on the website for each project board includes the magazine and issue where the article was published, but there is really no other description of the project other than the title. Therefore, it might take a little research to find out the details of the project. You can order reprints of the article
with the board for an additional $1.50.
It’s worth spending some time looking through the listings, as having a circuit board makes construction a homebrew project much easier. Looking at this list is also an easy way to find a reference for project you may have read about a few years ago, but can’t remember where you saw it. Here are some of the projects I found that might appeal to Natural Radio Experimenters:
- VLF SPACE SHUTTLE RECEIVER
- JOE CARR VLF RECEIVER
- GYRATOR RECEIVER
- A SIMPLE 10MHZ WWV RECEIVER BY MCKEAN
- REMOTE TUNED ACTIVE ANTENNA/CORNELL (2 BD SET)
- CORNELL WIDE BAND RECEIVER AMPLIFIER
- CORNELL REGEN RECEIVER PREAMP
- AAVSO VLF RECEIVER PREAMP BY CARR
- AAVSO RECEIVER BY CARR
There are also some audio amplifier boards that could be used as the headphone amp for a Natural Radio Receiver. If you are considering building a beacon transmitter, there are projects for automatic keyers and oscillators.
Check out the website at http://www.farcircuits.net/ or contact them at:
18N640 Field Court
Dundee, Illinois 60118
(847) 836-9148 Voice/Fax
Page created by Mark Karney