This question concerns the coil detection pattern above and below the coil. I was bench testing a VLF coil today, using about 1/2 gram of flake gold (several pieces) secured between scotch tape. I attempted to detect the sample beneath the coil and could manage only very scratchy reaction, and that with the sample almost pressed against the coil. By accident, I passed the sample over the top of the coil and was surprised by a very sold hit. After several passes, up to around 5 inches, I continued to have this reaction. I again tried below the coil, with no reaction.
Thinking I had a defective coil, I tried other items, gold chain, gold and silver rings, coins, pull-tab, etc. etc. and all gave good signals within the expected range.
So for the question. In a VLF coil, is it possible to have two difference frequencies operating at the same time? Unless there is a scientific reason the gold was detected above and not below, it would appear a higher frequency is being generated above the coil. Does this make sense?
Confused.
Thinking I had a defective coil, I tried other items, gold chain, gold and silver rings, coins, pull-tab, etc. etc. and all gave good signals within the expected range.
So for the question. In a VLF coil, is it possible to have two difference frequencies operating at the same time? Unless there is a scientific reason the gold was detected above and not below, it would appear a higher frequency is being generated above the coil. Does this make sense?
Confused.

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