Field generator

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Transmitter coil

An total of eight transmitter coils are used in the Anser EMT system. Each coil emits a time-varying magnetic field in the 20kHz band. Each coil is connected to a single channel of the Signal Generator AC Amplifer stage. The transmitter coil is fabricated as a printed circuit board. Schematic and Gerber files for the coil design are available in the project repository. The design for a single PCB coil is shown in the figure below. A vector image of this figure can be found here.

Coildiagram.png
Coilphoto.png
Biotsavart.png


The dual-layer PCB shares a single winding between the top and bottom layers. A total of 25 coil turns are present in the design. L1 and L2 denote the PCB via's where the PCB winding switches layer. The square PCB measures 72mm in length. A photo of a fabricated coil is shown below.

The magnetic field emitted by each coil is modelled using the current filament method described by Sonntag et al.. Each straight-line copper 'filament' of the PCB coil is treated as a uniform individual current-carrying conductor. The magnetic field due to each filament is calculated using the Biot-Savart law. The field strength from each individual are added using superposition to provide the total magnetic field of the PCB coil. The diagram below shows a single current-carrying filament with current II being observed from a point P=(x,y,z)P=(x,y,z).