Detectores

SearchcoilTech Sheet
GARRETT: The Global Leader of Ground Search Metal Detectors

SEARCHCOIL BASICS
The searchcoil is a vital part of your metal detector. It is the flat, typically circular disk, which generates a magnetic field and senses metallic targets in the surrounding environment. It is located at the end of the stem and is connected to the control housing via a cable that is woundaround the stem. The size, depth and energy output (power) of the magnetic field is determined by the shape and size of the searchcoil. Understanding the purposes behind the various sizes and shapes of searchcoils will empower you with the ability to choose the best searchcoil for the right application.

Searchcoil Cable Control Housing

HOW SEARCHCOILS WORK
Searchcoils generally consist of twointernal sets of coiled wires, a Transmit Coil (TX) and a Receive Coil (RX). Mono coils can be different in that one coil acts as both the TX and the RX. When the detector is turned on, the TX coil generates a magnetic field in the surrounding space. When a metallic object is within this generated magnetic field, it will create a distortion in the magnetic field. The RX coil will sense thisdistortion and send a signal to the control housing. A searchcoil’s detection pattern is determined by the combination of the TX’s generated field pattern and the RX’s sensing field pattern.

SEARCHCOIL DEPTH

Generally speaking, the larger the searchcoil, the larger the magnetic field.

The detection depth of a searchcoil, as a rule-ofthumb, will be approximately equal to its diameter, for acoin-sized object. However, as a searchcoil’s size increases and its field pattern becomes larger, the field pattern becomes less concentrated and begins to miss small objects. For a coin-sized object, this effect becomes noticeable when using searchcoils larger than about 15” in diameter. Since the field generated by a large searchcoil is larger, deeper and less concentrated than a small searchcoil,it is the best choice when hunting for targets that are usually large and deeply buried, such as caches or relics.

The transmit coil (TX) creates a magnetic field while the receive coil (RX) senses distortion in this field and signals the control housing.

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SearchcoilTech Sheet
GARRETT: The Global Leader of Ground Search Metal Detectors

SIZES &SHAPES
There are a variety of searchcoil sizes and shapes. The correct one to use depends on the environment and applications it will be used in as well as the targets you seek. A change in any one of these variables may require a different searchcoil. Generally, searchcoils are circular or elliptical in shape. An elliptical Circular searchcoil, considered more maneuverable than a circularsearchcoil because its narrow width actually provides greater coverage than a circular coil due to its elongated length. However, a circular searchcoil has slightly more detection depth and sensitivity in non-mineralized soil, so it is still the most commonly used shape. Searchcoils also come in a 2-box configuration, which are used for Elliptical detecting deeply buried targets. Searchcoils range in sizefrom a few inches to several feet. Those which are less than 6” in diameter are generally considered small, 611” in diameter are considered medium and over 11” is considered large. As noted earlier, there is a direct relationship between the size of a magnetic field and the size of a coil. The bigger the coil, the larger the magnetic field. Therefore, larger searchcoils generally detect deeperthan smaller searchcoils.

2-Box

Small Searchcoils The magnetic field of a small searchcoil is concentrated within a small volume, therefore is the best choice for hunting in areas with a lot of metal debris. This allows you to maneuver through and around trash to locate good targets, especially when searching in tight places where large searchcoils cannot go. In addition, because of their...