Not as easy as one would think - this phase canceling of H fields.
Try to picture a loop antenna (coil what ever) radiating a
sinusoidal wave - donut shaped - with the center as the axis.
As this field radiates outwards close to the loop or coil, it is
a complex near ElectroMagnetic field. Granted, the E-Field is
very small, while the H-Field is large, however the H-Field is
decreasing in magnetude as 1/(r^3) away from the loop, until it
gets to the fresnel region where is starts to approach 1/(r^2)
in magnitude.. until it reaches the far field.
Now.. in order to cancel this field, we need to match the field
intensity AND the phasing of the wave. ONLY at a point in space
will this occur unless you can perfectly match the decaying
field intesity AND phasing through space (extremely unlikey and
improbable).
So this leads me to think something else is happening here, maybe
shaping the H-Field with High Perm material, making the field
more concentrated while also making the source smaller and more
efficient. Establishing a field someplace else in space and
trying to phase cancel a "wave" (not a point) to me would be
virtually impossible. Try the math and you'll see! Use three
space too as this would make it all valid. NEC 4.0 would be a
good computer modeling tool to use for validation modeling.
v/r Ken Carrigan