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What Is The Optimum Axiom Coil For Larger Deep Targets?


Az_Ed

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I'd like to focus on searching for 1-3 oz (2-4 square inches) or larger size targets that are deeper, perhaps more than one foot down.  The ground I'm searching is moderately mineralized and easily handled by the 11x7" mono.  I currently have the 13x11" DD and the 11x7" mono.  Would the 16x14" mono be a significant improvement in depth for larger targets?  I understand the differences between the DD and mono coils, but I don't fully understand their differences in detection depth,  especially on larger targets.  Thanks for any help or comments.  Az_Ed

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Depth gains are real but not dramatic unless the coil size difference is dramatic, as measured in square inches of coil size. This article below pretty much says it all. In your case if talking multi ounce nuggets, the 16" mono would be the way to go for now, until other larger options appear. But the gain will be a few inches at most, not double or some such thing. 

For every target there is an optimum coil size, and going to a larger or smaller coil than that optimum will get you less depth. To repeat, going to a larger coil can lose depth if the coil you have is already best for your target. People swinging super large coil sizes are losing depth on the most common targets sizes and only winning with the largest.

Conversely, there is an optimum target size for each coil, and both larger and smaller targets than the optimum will lose depth compared to using a coil optimized for that size.

Most detectors are optimized for coin size targets using an 11" coil. Smaller targets benefit from smaller coils, and larger targets from larger coils.

I should mention mineralization and EMI also. Large coils see more of both relative to target size. These two factors work against larger coil sizes and can negate some or all of the theoretical gains. See the link below for details.

  • Coil Size vs Detection Depth by Carl Moreland, on this website forum. A chart with notes from PI guru Eric Foster illustrates the relationship between coil size and depth.
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