As a rule of thumb, the lower the frequency used by the metal detector, the deeper it can penetrate the ground. At low frequencies however, sensitivity to small low conductive targets is reduced. The higher the metal detector’s frequency, the higher the sensitivity to small targets, but will not penetrate as deeply. In general, gold detectors operate at higher frequencies (to find small nuggets), while coin and treasure detectors work at lower frequencies for deeper penetration. The exception to this is MPS type metal detectors that are sensitive and deep seeking simultaneously.

Size: The size of a search coil of a metal detector can influence the detection depth or sensitivity of a metal detector. The larger the coil, the deeper it detects, but will have less sensitivity to small targets. Conversely the smaller the search coil’s diameter, the more sensitive it becomes but looses detection depth. Smaller coils in metal detectors are lighter, easier to control and may be chosen for their ability to negotiate difficult terrain or undergrowth. They are also an advantage in areas of high trash.

Shape:  The most common coil shapes are conventional solid round coils, elliptical shaped coils and the open web coils. The main reason for the change in shape is to conform to a physical requirement, i.e. an elliptical coil can be pushed around bushes or between rocks easier than a round coil and open web coils move through water easier and are lighter. Conventional round coils are often more stable and perform better and are particularly popular for gold prospecting.

Configuration: The three most common types of coil windings are Concentric, Double-D, and Monoloop. The difference between these coil types is the pattern the wire is wound within the search coil.

There is no specific answer to this question as it depends on the target size, orientation, metallic content, ground minerals and conductivity, electrical and ambient noise in the area and etc.

Gold chains are very difficult to detect, particularly very fine chains. Each link of a chain can be very small and the detector sees each link as a separate target, so it can easily be missed. You are more likely to detect the actual clasp or any pendants that may still be on the chain as these are much larger than the individual chain links.

Metal detectors pick up electromagnetic signals from underground metal objects. Similar signals can also be received through the air from other electromagnetic sources, such as power lines, radio transmitters, generators, etc.

This can be caused by a number of reasons:

• Sometimes rusty objects get broken up during the digging process
• Metal objects can leach trace elements into the surrounding soil
• Some rocks can sound like targets
• Some targets get ‘lost’ or reburied during the digging process

Usually because you are lifting the coil at the end of your swing. Always sweep slow, low and level for the entire swing.