Fluxgate

Abstract

A fluxgate including at least two ferromagnetic or ferrimagnetic, flexible cores, and at least two sets of a plurality of windings of an electrically conductive material. At least one set of windings is wound around each of the cores. The fluxgate further includes an electrically conductive, flexible shield enclosing the cores and the windings.

1 . A fluxgate comprising: 
 at least two ferromagnetic or ferrimagnetic, flexible cores;    at least two sets of a plurality of windings of an electrically conductive material, at least one set of windings being wound around each of said cores; and    an electrically conductive, flexible shield enclosing said cores and said windings.    
   
   
       2 . A fluxgate according to  claim 1 , comprising a first flexible insulating means for electrically insulating said cores from said windings.  
   
   
       3 . A fluxgate according to  claim 2 , wherein the first insulating means comprises at least two flexible, electrically insulating tubes, wherein each core is surrounded by a said tube and said sets of windings are wound around said tubes.  
   
   
       4 . A fluxgate according to  claim 1 , wherein the electrically conductive material of said windings is coated with, or surrounded by, electrically insulating material.  
   
   
       5 . A fluxgate according to  claim 1 , further comprising a flexible insulating jacket provided around said shield.  
   
   
       6 . A fluxgate according to  claim 1 , wherein said magnetic cores comprise a high magnetic permeability saturable material.  
   
   
       7 . A fluxgate according to  claim 1 , wherein said cores comprise a soft ferromagnetic or ferrimagnetic material.  
   
   
       8 . A fluxgate according to  claim 1 , wherein said cores are sufficiently thin so that the magnetic properties of said cores are not substantially altered by stress/strain induced by flexure.  
   
   
       9 . A fluxgate according to  claim 1 , wherein said cores comprise Mu metal.  
   
   
       10 . A fluxgate according to  claim 9 , wherein said cores comprise strips of Mu metal foil.  
   
   
       11 . A fluxgate according to  claim 1 , wherein said cores comprise Mu metal of 0.2 mm thickness or less.  
   
   
       12 . A fluxgate according to  claim 1 , wherein said cores comprise Mu metal of 0.1 mm thickness or less.  
   
   
       13 . A fluxgate according to  claim 1 , wherein said cores comprise Mu metal wires.  
   
   
       14 . A fluxgate according to  claim 1 , wherein said cores comprise an evaporated film of ferromagnetic or ferrimagnetic material.  
   
   
       15 . A fluxgate according to  claim 1 , wherein said windings are helical windings.  
   
   
       16 . A fluxgate according to  claim 1 , wherein said windings are single layer helical windings.  
   
   
       17 . A fluxgate according to  claim 1 , wherein the length of the fluxgate is at least 0.5 m.  
   
   
       18 . A fluxgate according to  claim 1 , wherein the fluxgate is sufficiently flexible so as to be able to be arranged substantially in the form of a loop.  
   
   
       19 . A fluxgate according to  claim 1 , wherein the fluxgate has first and second axial ends and is sufficiently flexible so as to be able to be arranged such that the first axial end is in close proximity to the second end.  
   
   
       20 . A fluxgate, arranged in an open loop.  
   
   
       21 . A fluxgate comprising: 
 at least two flexible cores;    at least two sets of a plurality of windings, at least one set of windings being wound around each of said cores, the cores and windings interacting with each other by magnetic coupling between a ferromagnetic or ferrimagnetic material and an electrically conductive material; and    an electrically conductive, flexible shield enclosing said cores and said windings.