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SEARCH COIL TYPES

A brief look at the various Coil types and configurations.

:   CONCENTRIC/COPLANAR  :  DOUBLE D   :    MONOLOOP   :    COAXIAL   :

CONCENTRIC / COPLANAR

Coil Windings 
A Concentric Coil consists of two different sized circular or elliptical rings, one inside the other on the same horizontal plane.
The larger Outer ring houses 1 or 2 Transmit coil windings, and the smaller Inner ring houses the Receive coil winding.

Electromagnetic Field
The Electromagnetic Field is Conical in shape which extends above and below the coil windings. The effect of being Conical in shape is that the Electomagnetic Field gets deeper and stronger the closer it gets to the center of the Coil. Therefore, the deepest penetration and greatest density is directly under the coils center.

EM Field - ConicalSide



PRO's
• Pinpointing is very easy and precise due to the strongest signal being at the center of the coil.

CON's
• Less stable on heavily mineralised ground and salt water areas.
• Requires a larger 'overlap' per sweep to avoid missing targets.

DOUBLE  D / 2D

Coil Windings
A Double-D coil consists of 2 "D" shaped coil windings that are placed back to back, with a small overlap along the center, front to back. Generally, the Left side is the Transmit coil winding and the Right side is the Recieve coil winding.

Electromagnetic Field
The Electromagnetic Field extends from the overlapping part of the 2 back to back "D"s and is shaped somewhat like the blade of a chisel or axe head. This gives a thin Electromagnetic Field that runs the full length of the coil from Front to Back.
As with the Concentric coil, the Electromagnetic Field extends above and below the coil windings.

EM Field - chiselFront EM Field - chiselSide EM Field - chiselSide EM Field - chiselSide



PRO's
• Covers more ground per sweep.
• Sweep overlap requirement is minimal and far less disciplined.
• More stable on heavily mineralised ground and salt water areas.

CON's
• Pinpointing can be a little difficult.
• Slower sweep speed is required.

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!! UNDER CONSTRUCTION !!

MONOLOOP

Coil Windings 
Unlike other coils, a Monoloop coil only has One coil winding. This single winding acts as both the Transmit and Receive Coil windings .

Electromagnetic Field
The Electromagnetic Field is Conical in shape which extends above and below the coil windings. The effect of being Conical in shape is that the Electomagnetic Field gets deeper and stronger the closer it gets to the center of the Coil. Therefore, the deepest penetration and greatest density is directly under the coils center.

EM Field - ConicalSide



PRO's
• P.

CON's
• L.
• R.

!! UNDER CONSTRUCTION !!

COAXIAL

Coil Windings 
A .

Electromagnetic Field
The Electromagnetic Field is also Conical, however, unlike the the other Conical Fields listed above, this one does not extend as deep as other types of coils of the same size. It also only extends DOWNWARDS. . . This means that if you were to wave a clump of soil over the top of the coil to see if the target is in that clump (as some detectorists do), there would be no signal, even if the target was in there.

EM Field - ConicalSide



PRO's
• Ps.

CON's
• Ls.
• Rs.