For those that understand the US patent system what does this mean? Does it now mean that this expired patent for using using Litz wire in coils is now patented again or what?
doug

Hopefully Allan  may be able to clarify exactly what the situation now is with regard to using litz wire used in coils?
doug

By why mention and incorporate by reference the Litz wire patent? This is what I don't understand! eg does it mean that it only applies to coils wound with litz wire?
doug

Can anyone see where this is going to lead? Could it be that the next ML model will only be warranted and "work properly" with new patented ML coils incorporating this new technology? 
doug

Hmmmm,

Is that a glorified patent on putting a ferrite bead around a solder joint to stop eddy currents forming in the solder joint? Thats what I can gather from it!

Cheers Mick

  I am sure the QED will not have a setting for finding " flea dung sized targets" will it Doug?  It would be against your views.

Hi All,

The description of the phenomenon that generates a signal within the coil itself
is essentially correct.  Magnetic modulation of the the amplitude of the signal
originating in the coil or nearby conductive objects was first observed in the
early 1970 and it was called the "magnetic illusion".

You can demonstrate this effect by holding a coin in front of the search coil
and moving a ferrite rod in front of it.  This creates the illusion of having
moved the coin, because the concentrated field through the coin increases the
amplitude of the signal.

Observation of this phenomenon resulted in the removal of a conductive shaft for
the coil and the ferrous mounting hardware.

It's important to recognize that magnetic material in the soil will change the
amplitude but not the time constant of the self-detecting coil signal.

Thus, if you use 1 mm diameter wire in your coil, the field from one wire
penetrating the adjacent wire will generate a signal with a time constant that
is similar to the signal from a nugget the size of a grain of rice.

If you are interested in detecting nuggets of this size, this patent application
may be of interest to you.

For most of us, however, this patent application has no practical consequence.

The statement that the Litz wire patent is incorporated in its entirety has no
consequence either.  It's there only for the sake of explaining the background.

It does not "reactivate" any of the old claims and it does not mean that the
patent applies only to coils wound with Litz wire.

In practice, a GB system will cancel out the signal originating in the coil and
in the soil at the same time.  My guess is that if this application ever matures
into a patent, it will lapse as soon as the maintenance fee become due, because
coils that make use of the patented technology will never enter the market place.

Just my opinion,

Allan