Strand wire winding method in a solenoidal coil with limited geometry for good impedance matching

This paper reports a new strand wire winding method in a solenoidal coil with limited geometry that enables good impedance matching. In the proposed method strand wires are wound layer-by-layer on top of each other allowing one to set equivalent inductance and resistance of the coil to desired values while obtaining dense magnetic flux and high current carrying capacity. As a proof-of-concept demonstration, simple model setups were constructed with solenoidal coils composed of copper wire strands wound according to the proposed method, and a plastic pipe. The measurements were repeated with a metal shell placed inside the coil to model a complete heating system. System inductance and resistance were measured at two different frequencies. The results show that with the new winding method it is possible to increase a coil’s turn number and the number of strand layers composed by the coil. Also, adding and removing strand layers in the proposed coil architectures enable inductance and resistance values to decrease and increase, respectively, in a controlled way. To understand changes of system parameters, simulations were also performed. The calculated inductance and resistance values in the simulations agree well with the measurement results and magnetic flux distribution created in the system demonstrates the changes.