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Originally Posted by ALEX.356
My friend ,
you oblige me with all your effort to assist me.
Question : Has anyone else attempted to make a similar devise on a more serious basis ? i.e with a real transmitter and directional receiver ?
Kind regards,
ALEX
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The method of using a loop antenna to survey an area that is exposed to RF is a standard way that geologists determine what is under the ground. They carry a hand-held loop antenna connected to their receiver while they walk across the area they want to survey. The transmitter is usually a large VLF transmitter hundreds of miles away operated by the military or some government which broadcasts at a frequency between 5 KHz to 30 Khz, or sometimes higher. If there is no reliable VLF transmitter nearby, then the geologist may set up his own portable VLF transmitter to send RF into the ground for his survey. When the geologist is done recording the readings of his survey, he can make a map to show a diagram of the geological structures beneath the soil. The geologist is interested in mapping rock formations and other geologic structures, not hunting treasure.
This geologist's method is the basis for the idea that treasure hunters use for detecting metals under the ground when using an RF receiver coil survey. Early experimenters set up loop antenna transmitters and used loop receiver coils to find large buried metal objects a century ago. Today, experimenters have built detectors in various configurations that send out VLF signals and check the signal with a loop coil receiver. You can find some technical information about how to do this in this thread:
http://www.geotech1.com/forums/showthread.php?t=16216
In the second half of the thread, WM6 and Seden become involved to help with their knowledge from their experience in ameteur radio, and explain some important details about the equipment, frequencies and power needed to expect some response. You will also see others posted ideas which include a few experimental projects that are related to the loop coil survey method.
There are also some other threads that show more about this.
Best wishses,
J_P