The depth detection on a metal detector can vary greatly depending on the quality. If the conditions are ideal and the targets are located up to one foot below the ground, you’ll be able to easily find what you need.
The factors that influence the search depth of detectors fall into two categories. Internal factors have to do with the metal detector itself, and external factors comprise of things not related to the detector itself.
For instance, the best depth metal detector in one area could be almost useless in another, depending on the condition of the soil. So what factors really affect how deeply a metal detector can go, and why do they affect it?
What is Detection Depth?
When we talk about detection depth, we are referring to how deep the detector can identify metals from the surface. Generally, basic detectors will pick up small jewelry like necklaces and small gold chains, between 7cm and 15cm. Big jewelry can be detected between 15cm and 30cm deep, while high-end detectors can detect up to 1.5 meters.
Even if you have a high-end detector, and the surface is very dry as opposed to wet, the detection depth will be lower. Other factors that affect the specific depth include the size of the metal and how it’s positioned. A basic detector will easily detect a big metal buried deeper on a wet surface. Mineralized soil will also affect the detection depth especially if the metal detector isn’t made for those surfaces.
Depth will also be affected by the technology being used by the detector, the size of coils, and batteries. If you are using large coils, you will likely have deeper detection, but you will be losing sensitivity.
How Do Metal Detectors Work?
Metal detectors typically come equipped with a search coil that transmits an electromagnetic field into the ground. Buried metal objects within the electromagnetic field become energized and create a changing magnetic field, which is detected by the coil and alerts you by producing a beep or click sound.
If a metal object is buried too deep into the ground, the strength of the magnetic signal it re-transmits diminishes before reaching the metal detector. In such a case, the machine will not identify the hidden treasure.
Some advanced metal detectors have a depth indicator feature, which shows you how deep you will need to dig.
How Size and Orientation Affects Detection
The size of the target hugely influences how accurate and deeply a metal detector can detect it. Typically, larger metal objects can be identified deeper into the ground than smaller ones. This is because larger objects capture more energy from the coil, allowing easier identification at a greater depth.
The orientation of the target also impacts the depth of a detector as objects in a horizontal position can be detected deeper than one that’s vertically positioned. A horizontal position allows targets to receive more energy from the detector and return a better signal to the coil for identification.
External Factors
External factors as we’ve covered are things that affect the detector that our in the environment you’re detecting. They aren’t things that are affected specifically by the detector itself.
Type of metal
All metals conduct electricity to some extent, but some are better conductors than others. Metal detectors can better detect highly conductive metals like silver at a greater depth than lower conductive targets like lead. This is because highly conductive targets usually return more reliable signals than low conductors or impure and corroded metals.
Soil type and Mineralization
Fields with heavy clay or densely compacted soils make it harder for the signal to penetrate than those with loose, well-aerated soils. Likewise, fields containing intermittent strata, massive rocks, and aggregate accretions can inhibit the return signal, making it difficult for the detector to identify targets deeper in the ground.
Grounds filled with minerals such as salts and ionizing chemicals usually interfere with the re-transmitted signal, preventing proper depth detection. This shows that metal detectors effectively pick up deeper targets in low mineralized grounds than those in highly mineralized areas.
Electromagnetic Interference
Electromagnetic interference from buried power lines, large utility transformers, WI-Fi signals, and nearby coin-hunters can often incapacitate your metal detector functionality, making depth detection more difficult.
Wet Ground
A wet ground makes it difficult for most detectors to go deeper. This is mainly because metal objects sink deeper a lot faster in wet grounds over dry fields, making it even harder for your detector to reach the target. However, some metal detectors come designed waterproof, allowing for detection deep in the waters.
Internal Factors
These factors are what may be going wrong within the metal detector itself. How the device operates within the environment can really make issues for you to find what you’re looking for.
Coil size.
The size of the coil directly influences your metal detector’s search depth and sensitivity. Generally, larger coils allow for deeper metal detection than smaller ones. However, detectors with larger coils often lose sensitivity and accuracy on smaller metal objects. On the contrary, smaller coils offer better precision and sensitivity but reduced depth detection.
Metal detectors usually come equipped with standard coils, but you can install larger ones such as Double-D coils, which can penetrate deeper into the ground for effective depth detection.
Type of technology
Sometimes your technology can be what’s at odds. There are several types of technology that are specifically helpful with deep-seeking.
Pulse induction technology
Pulse Induction is a technology that effectively locates targets deeply hidden in the most difficult terrains. The technology works by transmitting many short electrical pulses in rapid succession to the ground. The return response signals from buried targets are then analyzed and showcased on the detector’s display.
This deep-seeking technology penetrates deep into the ground to quickly distinguish between valuable and non-valuable metals. It also works perfectly well in a vast range of field conditions, including mineralized and salty soils.
3D Imaging Systems
This is an advanced metal detection technology that displays image scans of buried metals in real-time. Both precious metals such as gold and junk metals are displayed clearly in full-color on a digital display. This helps distinguish the different metals underneath and know their exact depth, shape, and sizes.
Gradiometer
This technology uses magnetic sensors to analyze signals in real-time and determine whether a target in the field is a mineral, metal, or cavity. When metals are detected, it displays a 3D image of the analysis on a digital display.
Long-Range Magnetic Locators
This technology helps detect the presence of magnetic signals within 1000 meters. It also shows the exact location of the source of signal on a digital display. This may come handy in identifying metals buried deep in the ground by checking for magnetic interference.
Very-Low Frequency
VLF is probably the most common technology for the detection of deep treasures. It works by sending signals out via a transmitter coil and captures the return signals through a receiver coil.
Multi-Frequency
This is a revolutionary metal detector tech that employs more than a single frequency, eliminating the limitation with single-frequency machines. It works by transmitting multiple frequencies at the same time, allowing the detection of deeper targets and sensitivity to smaller items simultaneously.
Frequency
Metal detectors operate at varying frequencies, and it determines how deep and sensitive machines can detect targets. Machines with lower frequencies often have greater depth detection than higher-frequency ones.
While lower-frequency metal detectors deliver superior depth detection, they often give reduced sensitivity to smaller metal items. Higher-frequency detectors, on the other hand, provide better sensitivity but less depth detection.
That being said, low-frequency metal detectors are the most ideal when it comes to picking up metals deeper in the ground. There are also new multi-frequency detectors that send multiple frequencies simultaneously, allowing detection of deep metal targets and sensitivity to smaller objects.
How to increase the level of depth?
First, you need to determine where and what exactly you’re looking to hunt. Whether it’s gold nuggets, copper, lead, or any other metal you’re looking for, they’ll all have different features you need to pay attention to for detection.
If your detector has stock coils and you’re planning to pick up targets in greater depths, then you will need to replace them with larger coils to achieve your goal.
When hunting in mineralized fields, you may want to adjust your metal detector’s ground balance settings to improve its detection depth. This helps discriminate false signals from minerals and pick up clear and non-distracted signals from valuable metal targets.
Increasing your detector’s sensitivity is another way to enhance its depth detection, but can as well produce more trash iron signals if turned up too high.
It is also recommended that you get a modern metal detector with advanced deep-seeking technologies to effectively go deeper into the ground and get valuable targets.
Another easy way to increase your detector’s level of depth is by setting minimum discrimination. This way, you don’t miss deeper target signals.
What are some of the best deep-seeking metal detectors?
One of the best machines for locating large, deeper targets is a two-box metal detector. Two-box detectors use a unique search coil to transmit signals deeper into the field. Once the signal comes across a metal target, it bounces off the object and returns to the detector coil signaling the presence of a potential target.
Some great examples of the Two-box detectors are the TW-6 metal detector or the Gemini-3 that come with an extended handle for better depth penetration through expanding the gap on the handle’s boxes.
Best Entry Level Deep Detectors
Entry-level deep detectors are relatively easy to operate and perform incredibly well in identifying objects more rooted in the ground. They, however, often don’t include features for distinguishing the type of metals detected, as the high-end models do. Some of the best entry-level detectors include:
Gemini-3
The Gemini-3 is an affordable, yet high-performance two-box metal detector that works well in locating large caches and relics deep in the ground. It is remarkably easy to use and can detect depths of up to 15 feet in ideal ground conditions.
Whites TM 808
The Whites TM 808 is another reasonably priced metal detector that can detect larger targets at depths of up to 20 feet. It is also a highly versatile detector as it can be used for identifying coins, gold, silver, and other metal objects. It comes fitted with two antennae that help you ignore various minerals in the ground and only get the actual treasures hidden further down.
Mid-level Deep Metal Detectors
Mid-level deep detectors are designed to locate and distinguish between valuable and junk metals. They can as well detect cavities in the ground, which may contain treasures. Some of the best ones include:
Garrett GTI 2500
The Garrett GTI 2500 comes integrated with the revolutionary Graphic Target Imaging technology that gives you a clear image of the target’s size, shape, and depth. This enables you to distinguish between the various minerals and metals in the ground.
Detech SSP 5100
The Detech SSP 5100 is an excellent deep detector that can achieve depth detection of up to eight meters from the ground. It is fitted with a unique coil that accurately detects precious metals such as platinum, gold, and silver located at a depth of four meters deep.
Professional Deep Metal detectors
Professional detectors are high-end machines that come equipped with more advanced features and technologies for greater depth detection.
Makro Jeohunter
The Makro Jeohunter is a versatile professional deep metal detector designed to locate gold as well as other metals found up to 12 meters deep. It displays full-color 3D images of the targets detected, giving you a clear picture of what and where to get the precious metals.
Conclusion
Many factors come into play when determining how far a metal detector can reach. This explains why some precious metals have been missed for many years, yet they’re only several inches down in the ground. This is why they are only retrieved later on using a more advanced metal detector. This shows how advancements in technology contribute to creating more efficient detectors that can locate metals deeper in the ground.
