Orthogonally isolated exciter with field steering

Abstract

Provided herein are systems, devices, assemblies, and methods for generating exciter signals, for example, to activate a remotely located tag. The systems, devices, assemblies, and methods find use in a variety of application including medical applications for the locating of a tag in a subject.

We claim: 
     
         1 . A device comprising:
 a base substrate,   a plurality of exciter coils coupled to the base substrate, and   a plurality of witness station assemblies coupled to the base substrate, wherein each of the plurality of witness station assemblies defines a sensing axis co-planar with the plurality of exciter coils.   
     
     
         2 . The device of  claim 1 , wherein each of the plurality of exciter coils comprises a central plane, and wherein the sensing axis of each of said plurality of witness station assemblies is co-planar with the central plane of each of the plurality of exciter coils. 
     
     
         3 . The device of  claim 1 , wherein the plurality of exciter coils is operated in three configurations to selectively generate a magnetic flux in three orthogonal directions. 
     
     
         4 . The device of  claim 3 , wherein the sensing axis of each of the plurality of witness station assemblies is isolated from the magnetic flux in three orthogonal directions by 50 dB. 
     
     
         5 . The device of  claim 1 , wherein the plurality of exciter coils includes four exciter coils are in a layout of two rows. 
     
     
         6 . The device of  claim 1 , wherein each of the plurality of witness station assemblies further comprises: a core having an end, a bracket, and an elastomeric part, and wherein the end is positioned between the bracket and the elastomeric part. 
     
     
         7 . The device of  claim 6 , wherein the bracket includes an adjustment part. 
     
     
         8 . The device of  claim 7 , wherein said the adjustment part allows the sensing axis of each of the plurality of witness station assemblies to be adjusted. 
     
     
         9 . The device of  claim 6 , wherein the core is ferrite. 
     
     
         10 . The device of  claim 6 , wherein each of the plurality of exciter coils comprises a central plane, and wherein the sensing axis of each of said plurality of witness station assemblies is co-planar with the central plane of each of the plurality of exciter coils. 
     
     
         11 . The device of  claim 1 , wherein each of the plurality of witness station assemblies is oriented on the base substrate such that the sensing axis of each of the plurality of witness station assemblies is orthogonal to magnetic flux generated by the plurality of exciter coils. 
     
     
         12 . The device of  claim 1 , further comprising a balun circuit electrically coupled to the plurality of exciter coils. 
     
     
         13 . The device of  claim 1 , further comprising a plurality of switches that control the direction of current through each of the plurality of exciter coils individually. 
     
     
         14 . The device of  claim 13 , further comprising a capacitor coupled to at least one of the plurality of switches. 
     
     
         15 . The device of  claim 1 , wherein the plurality of exciter coils includes a first exciter coil, a second exciter coil, a third exciter coil, and a fourth exciter coil. 
     
     
         16 . The device of  claim 15 , wherein the first exciter coil, the second exciter coil, the third exciter coil, and the fourth exciter coil are operated in three configurations to selectively generate a magnetic flux in three orthogonal directions. 
     
     
         17 . The device of  claim 16 , wherein in one of the three configurations, current in the first exciter coil, the second exciter coil, the third exciter coil, and the fourth exciter coil travels in the clockwise direction. 
     
     
         18 . The device of  claim 1 , wherein each of the plurality of exciter coils includes a ratio of inductive reactance to resistance of at least 350. 
     
     
         19 . The device of  claim 1 , further comprising a pad and wherein the base substrate, the plurality of exciter coils, and the plurality of witness station assemblies are positioned within the pad. 
     
     
         20 . The device of  claim 19 , wherein the pad is configured to be positioned beneath a patient.