In the actual literature existent about planar coils, several works are developed on microcircuits, which the analyzed effects are based on sinusoidal excitation voltages. When analyzing the inductance of the coils, some works present results of the existence of parasitic capacitances (or stray capacitances), that interfere on the system on several aspects, as transformers. In these researches, several evaluations about effects of the parasitic capacitances at planar coils and ring coils with diameters greater than two centimeters, as response of the induced eletromotive force in the ring coil when a step voltage excites the primary are not found at literature. Actually little is found in researches about the effects of the square waves applied in coils as exciting voltages, where most researches of exciting voltages being square waves is applied to power electronics or others. In this paper published at Progress in Electromagnetics Research B (PIER B) are presented some experimental results about the observed effects in these systems deﬁned by planar coil versus ring coil, where the planar coil presents two thousands of turns maintained ﬁx; this planar coil is considered as the primary of an air core transformer (or input transformer) and the ring coil is considered the secondary of this transformer (output transformer, where the responses are obtained), which has the number of turns varying on worked experiments.
The results are presented in this paper, where the equipments used in these experiments were a digital storage oscilloscope Agilent Technologies DSO3202A with passive probe N2862A (input resistance = ten MOhm and input capacitance twelve picoFarads), a function generator Rigol DG2021A that generates the limit of twenty five megaHertz in the output to square wave, and a digital multimeter Agilent Technologies U1252A. Several important results are obtained with these experiments that are presented in this paper, being a work of very importance to the area of electromagnetics theory.