The first part that senses metal in the metal detector is called the metal detector search coil, which plays a very important role in the accuracy and penetration depth of the metal detector. The size and depth of the magnetic field is determined by the shape and size of the search coil. The choice between the types of metal detector search coils should be made according to the exploration environment, ground conditions, dimensions and material of the target, and one thing that should always be considered is the compatibility of the search coil with the metal detector.
What is Metal Detector Search Coil and How Does it Work?
As mentioned, the search coil is one of the most critical parts of a metal detector, which is a flat and usually round disk that produces a magnetic field. The search coil detects metal targets deep in the ground and is located at the end of the metal detector handle, which is connected to the main control panel by a cable.
Metal detector search coils generally include two strands of twisted wire. Some search coils have a coil that plays both the role of Transmit Coil and Receive Coil. When the metal detector is turned on, the transmitter coil creates a magnetic field in the surrounding environment.
When a magnetic object collides with this created magnetic field, it causes a distortion in the magnetic field, which the receiver coil detects this distortion and sends a warning signal to the main control panel.
Types of search coils in terms of size and shape
Search coils with a diameter less than 6 inches are called small coils, medium coils between 6 and 11 inches and larger than 11 inches are called large coils. As we mentioned earlier, there is a direct relationship between the size of the coil and the magnitude of the magnetic field, and the larger the magnetic field, the greater the accessible depth.
In general, most coils are circular or elliptical. Elliptical coils have more maneuverability than circular ones, and their narrow width gives better coverage than circular coils, and the reason is their longer length, however, the depth of exploration of circular coils is slightly more than elliptical coils, and also the sensitivity. They have more in non-mineral soils.
Configuration of search coils
A search coils treasure finder may have any of the following configurations. The difference in configuration causes a change in the sensitivity, penetration depth, error rate and recovery speed of the device.
- Concentric
- Mono
- Imaging
- Double-D configuration
- Two-box configuration
Depth accessible with search coils
The depth of search available in the search coils of metal detectors with a thumb calculation has a direct relationship with the diameter of the metal detector coil. As the diameter of the coil increases, the magnetic field produced by it also becomes larger, and as a result, it becomes less concentrated and starts to ignore small metal objects.
For example, for a dime, this effect is more effective when using coils larger than 15 inches in diameter than when the magnetic field produced by the coil is large enough to search for large, buried targets.
Important points in buying a metal detector search coils
Buy search coils that are waterproof and have protective covers. Make sure the coil is compatible with your metal detector. If you intend to find gold, use the coils that are optimized for this work, if you intend to penetrate deeper, use the 2Box coils.
If you want to have minimal interference with the Earth’s magnetism, Double D coils are a good choice, for better punctuation use Concentric coils. In order to cover a wider area and scan a specific environment in a shorter time, use coils larger than 11 inches. The way you move the metal detector coils over the ground has a huge impact on your success.
