Distributed Capacitance of Spiral Coils and Its Magneto-Capacitance Effect

The characteristics of distributed capacitance and impedance of hollow coils are studied theoretically and experimentally. The frequency characteristic, the number of turns and winding mode dependent capacitor of the coil, and the impedance versus number of turns of hollow coils have been measured, respectively. The distributed capaci- tance has been observed almost irrelevant to the number of turns and the winding ways of the coils when the number of turns is greater than 10. By measuring the magneto-capacitance effect of spiral coil, it was found that the distributed capacitance of coil relates to the coil material, suggesting the influence of skin effect. From the coil equivalent circuit, combining with the skin effect, an approximate formula of distributed capacitance and impedance have been worked out. Analysis showed that the distributed capacitance of coil mainly originates from line capacitance and the capacitance between turns.