The first thing that concerns us when buying a metal detector is how deep our detector can find a target . This question is legitimate, because statistically, the more detector can locate a target in depth, the more target can be found.
Current metal detectors, I’m sorry to say, do not reach great depths, and it is highly likely that they will not be able to reach the desired depth in the future either.
What is the average depth that a detector can reach?
An entry-level detector, which can cost between $ 200 and $ 350, will normally be able to detect a coin 20/23 centimeters in the ground. A mid-range detector, which would cost between € 400 and € 600, would reach a room between 25/30 centimeters and high-end sensors priced above € 700 would reach 33 to 40 centimeters depending on the size of the room.
This does not mean that a particular machine, under very specific conditions, can detect a part at a greater depth. On the market, you can find equipment capable of reaching greater depths, but be aware that they are designed for large objects and large masses.
The big difference between conventional detectors and deep sea detectors is the level of identification they can provide on the target. For example, pulsed induction detectors are able to pick up targets deeper, but have a very limited conductivity identification panel.
The VLF type of recreational metal detectors usually provides very good information on the target, while machines designed for deep water are limited to indicate the presence of a metal object without knowing its nature.
The different frequencies and their penetration into the ground
The metal detector emits an electromagnetic wave that can travel in any medium, even in a vacuum, but this does not mean that this movement is optimal in any medium. To put it simply, low frequencies tend to penetrate the ground better, but provide less information about the nature of the target found due to their low resolution.
This is why detectors using higher frequencies are much more precise in identifying the type of metal, which at the same time improves the discrimination of certain types of metals such as iron. This is how it is concluded that high-frequency detectors are much more stable with respect to soil mineralization and waste identification.
Ultimately, high-frequency detectors obtain more information on the target found, but penetrate less well into the ground and experience a loss on the depth of attachment of the targets.
Conversely, detectors using low frequencies will have greater penetration into the ground but will have difficulty informing us about the buried object.
It is not easy to increase the depth of a metal detector because even if we do manage to increase the source of the emission, it will not translate one hundred percent into “depth”. It all depends on the target’s ability to capture the energy of the electromagnetic wave and return it to the receiving coil, as well as the dissipation of the energy generated by the detector into the ground (part of the energy wave is lost along the way).
For all these reasons, it is very important, when buying a metal detector, to take into account the capacity of the microprocessor of each model, its speed, and its ability to analyze the information received by the disc, in order to obtain better results when prospecting.
When buying a metal detector, always beware of false advertising that promises extreme depths. Remember that a detector can hang targets at a maximum of 30 to 35 cm. Focus on the big brands that already have many years of experience in developing quality products.
Try to avoid buying very inexpensive detectors that usually beep and end up throwing away.
Julie comes from a long line of metal detectors. Her family has been in the hobby for over 45 years and has recovered large amounts of civil war artifacts as well as a fair number of bottle caps. Lately she has been focusing on metal detecting in the Rocky Mountains.