Hobbies And Interests
Search Coil Characteristics
Metal detector search coils are defined by three broad characteristics: size, shape and configuration. The larger the coil, the deeper it can detect metal targets, but the less sensitivity it will have for smaller targets. Coil shapes are determined by their wire windings as seen from overhead, such as concentric, elliptical or open web designs. There are many winding configurations, such as Double-D, mono loop and concentric or elliptical coils. Each type of coil is used for specific reasons.
Concentric Coils
Concentric coils are the most commonly found coils on metal detectors. As their name suggests, these coils are round, generally 8 to 10 inches in diameter, although they can be quite a bit larger. Concentric coils can be thin, thick, solid or doughnut-shaped. Some concentric coils use a bracing for the coil windings which give the appearance of a spider's web. These are called spider coils or open web designs. Some metal detector users find the spider coils are a little sturdier and seem to present fewer false signals than the standard concentric coils.
Elliptical Coils
Elliptical coils also take their name from the shape of the unit. The main advantage of this design is that it can cover an increased amount of ground for each sweep of the coil when compared to a concentric coil with the same coil area. Elliptical coils can also be maneuvered more easily around bushes and between rocks than the concentric coils. However, it can be more difficult to achieve precise pinpointing of small targets with the elliptical design.
Double-D Coils
The Double-D coils have windings shaped like two opposing letter D's. This configuration provides a chisel-shaped signal that covers the ground uniformly. Pinpointing can be very accurate with the Double-D coils. These coils are often not as deep-seeking as the concentric and elliptical coils, but they enable a wider scanning of the ground. They are also not as affected by heavy ground mineralization.