Magneto-inductive waveguide

1. A magneto-inductive waveguide comprising a plurality of resonant elements, the plurality of resonant elements including:

a first resonant element comprising a conductive loop broken by at least one capacitive gap, and

a second resonant element comprising a conductive loop broken by at least one capacitive gap, the second resonant element magneto-inductively coupling with the first resonant element; wherein

the first resonant element and second resonant element are conductively coupled, and the first resonant element has a size that is smaller than 1/20 times a wavelength of a free space electromagnetic wave having a frequency equal to a resonant frequency of the first resonant element and the plurality of resonant elements are arranged to propagate a magneto-inductive wave.

2. The magneto-inductive waveguide of claim 1 , wherein the respective conductive loops of the first and second resonant elements have a common portion, whereby the first and second resonant elements are conductively coupled.

3. The magneto-inductive waveguide of claim 2 , wherein the respective conductive loops of the first and second resonant elements have a common capacitive gap.

4. The magneto-inductive waveguide of claim 1 , wherein the magneto-inductive waveguide is arranged such that there is essentially no coupling between the waveguide and free space radiation.

5. The magneto-inductive waveguide of claim 1 , wherein the first resonant element has a size smaller than 1/30 times the wavelength of a free space electromagnetic wave having a frequency equal to the resonant frequency of the first resonant element.

6. The magneto-inductive waveguide of claim 5 , wherein the first resonant element has a size around than 1/100 times the wavelength of a free space electromagnetic wave having a frequency equal to the resonant frequency of the first resonant element.

7. The magneto-inductive waveguide of claim 6 , wherein the first resonant element has a size smaller than 1/150 times the wavelength of a free space electromagnetic wave having a frequency equal to the resonant frequency of the first resonant element.

8. The magneto-inductive waveguide of claim 1 wherein neither of the first or second resonant elements are coupled to a ground plane.

9. The magneto-inductive waveguide of claim 1 comprising conductors arranged along lines of a grid, the conductors defining the plurality of resonant elements, wherein

the conductors meet at nodes where lines of the grid intersect, and capacitive gaps are formed in the conductors between pairs of adjacent nodes such that the adjacent nodes are not joined by a conductive path.

10. The magneto-inductive waveguide of claim 9 , wherein the conductors define the shape of the resonant elements to be one of: square, rectangular or triangular.

11. The magneto-inductive waveguide of claim 1 , wherein the plurality of resonant elements are arranged to propagate at least one of power or data by the magneto-inductive wave.

12. The magneto-inductive waveguide of claim 11 having a dispersion relation given by

cos h (/ f )=2 Z /( Z−joM )

where / is the propagation constant, d is period of the plurality of resonant elements, Z is the impedance of each resonant element, co is the angular frequency of the magneto-inductive wave, M is the mutual inductance between the resonant elements, and j=V−1.

13. The magneto-inductive waveguide of claim 11 , wherein the plurality of resonant elements are arranged to be magneto-inductively coupleable to a resonant element of an external device, such that the at least one of power or data may be transferred between the magneto-inductive waveguide and the external device.