Metal Detector Coils

Different components of metal detectors serve specific functions. These hardware parts are directly or indirectly linked to detecting hidden underground objects. Since the coil is the main part of the metal detector, people want to know about its purpose.

So, this article explains metal detector coils in detail. We will explore the coils, types of coils, which coil is suitable for which purpose, and what the user must keep in mind about metal detector coils.

But before we dive into it’s purpose, let’s first find out what they are so that their function becomes apparent:

What are coils?

The coils are the lowermost hardware component of the detector. Their role is to send signals into the ground and receive the energized alerts back from the earth.

Coils are made of wires and are protected in such a way that no dust or water splash could damage them.

Since metal detection is an outdoor activity, it is purposely designed to resist harsh weather. Sometimes, the person has to dive undersea to hunt down deep-sea treasures.

Types of Metal Detector coils

Coils come in different shapes and sizes. There are different grades of coils, but two of them are the most common.

  • Mono coil
  • DD coil
  • Mono coil

To learn in-depth about these coils check out Types of Metal Detector Sensor.

These are single-loop coils with distinct advantages and disadvantages. Generally, metal detectors are incorporated with mono coils.

Why does coil shape matter?

If the search coil diameter is small, it will send current pulses in a smaller radius area. It means that a small area will be covered, but you will receive more accuracy. But if you aim to detect large-size objects, then a larger coil will be more suitable.

A standard-size coil is normally 11 inches in range. This size of coil is an ideal fit for catching coins and relics. Because the standard coil provides decent depth.

However, if you want maximum depth, you can increase the search coil size.

Learn How to test a metal detector coil to check its capabilities. This will also help you to figure out whether your coil is working properly or not.

Pros and cons of mono coils

Pros of Mono coil

The single-loop design allows for maximum depth and deeper signal penetration below the surface.

It can tell the difference between ferrous and nonferrous metals, but it’s not as accurate as the DD coil.

Cons of Mono coil

Due to its design, it may not provide as accurate discrimination between ferrous and nonferrous metals as the DD coil.

Pros and cons of DD coils

Pros of DD coils

The DD coil has two loops. Its main advantage is the discrimination feature that shows different types of metals.

If you want to discriminate using sound or reject iron, you will get precise and trustworthy results.

Cons of DD coils

The depth potential of the DD coil is relatively weaker than the mono coil.

If the 11-inch mono coil can detect objects almost 4 feet deep, then the 11-inch DD coil can only detect objects up to about 3.5 feet deep. The depth depends on the size and ground condition as well.

Coils with frequencies

Technology is improving rapidly, and manual things are becoming mechanized. Now coils are coming with built-in frequencies.

If you want to use different frequencies for detection, you don’t have to replace the whole detector. You only need to replace the coil, and the entire device will work as a new one.

For example, there is a device that supports an 11-inch coil, specifically for coins and relics. Similarly, if a high-frequency coil is incorporated, it will detect gold nuggets. If large 13-inch coils are placed in the device, it will target objects at extreme depths.

So, in brief, a single device will be a multi-purpose device that serves three purposes.

Coil safety and protection

Since metal detection is an outdoor hobby, the detector must be shielded at any cost. Because if water penetrates the device coil, it will be badly damaged.

Manufacturers also provide instructions to protect the coil from unexpected incidents. Besides this, coil covers and coil protectors are available in the market, designed for coil safety.

There is a Canadian brand that offers its customers inflatable coils. They are convenient and easy to use. A balloon inflates surrounding the coil, which protects the coil from severe environments.

Waterproofing in coils

Some coils can withstand shallow water, while others work well in deep-water searching, including oceans. So, as a user, you must determine your requirements and match them with the coil features.

Weatherproof devices can bear only water splashes, such as raindrops. Whereas complete waterproof devices can be wholly immersed in water.

Optional coils from other brands

Some brands are dedicated to selling only coils. These companies don’t make detectors, but they do make coils for metal detectors.

However, we recommend that you buy coils from the manufacturer itself and not from other brands. Because using an optional coil from a different brand may turn out to be incompatible and cause hazardous damage to your device.

Nonetheless, some high-quality brands deliver promising optional coils. So, as a detectorist, you can consider these top-of-the-line brands when purchasing coils.

Wireless coils

There are advanced devices in the market that are completely wireless and lightweight. They can easily connect with the control unit and are user-friendly.

In addition, you have the option to remove the shaft. The control unit of these detectors is often portable. So, if the person desires to work with privacy, wireless coils are the best choice.

Cable coils

The cable coil is another category that is larger, and its diameter is approximately 1 meter or more. These coils are lightweight and easy to swing around the ground.

Pulse induction devices use cable coils. PI technology is not affected by instability and can support large coils. Cable coils are commonly found in powerful devices.


So, metal detector coils explained in detail. As a rule, a small-size coil is perfect for providing accuracy but with low depth potential.

On the contrary, a large-size coil is ideal for extreme depth potential but the user has to compromise on accuracy.

Remember that every grade of the coil has its plus side and negative side. Mono coils provide excellent depth, while DD coils offer excellent discrimination. You just have to meet your demands with the coil’s qualities.

Now that you know what different types of coils are and what purpose they serve, you can decide for yourself which coil suits your particular needs and make a decision to purchase accordingly.

Always remember to protect your coil from extreme environments. This will prevent coil damage. Also, take into account the waterproofing feature for your detection needs.

You should purchase coils from the manufacturer, but you can also consider high-quality brands as an option. Similarly, if you are searching for a portable coil, then a wireless coil is the ideal option. But if you are looking for a larger size and lightweight coil, then you must trust cable coils.

I hope you are now clear with your doubts regarding metal detector coils.

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