Evaluation of a quasi-coaxial printed circuit board transformer

Purpose: The purpose of this paper is to investigate the possibility of utilizing printed circuit board (pcb) technology to manufacture coaxial transformers and to increase the predictability, accuracy and repeatability of the transformers leakage inductance. Design/methodology/approach: The geometry of a coaxial transformer is approximated using pcb techniques. Several different geometries are presented with the outer coaxial conductor being approximated by discrete conductors varying from four to 36 in number. Finite element methods as well as experimental results are used to support the proposed ideas. A planar transformer is also analyzed in the same way to emphasize the design advantages offered by the proposed quasi-coaxial transformer. Findings: The proposed multi-conductor structures can be applied as co-axial transformers. The experimental values obtained for the leakage inductance of the coaxial structures correspond well to the predicted values. This is not the case for conventional planar structure where adjustments need to be made in the finite element analysis simulations to accommodate the shortcomings of the analytical calculations. Originality/value: In applications where the prediction of the leakage inductance of a transformer is important, this method may be applied and has the advantage of conventional pcb manufacture techniques.