The
basket winding method is used for coils designed for use at
frequencies of 50 kHz and higher to reduce two undesirable side effects,
proximity effect and
parasitic capacitance, that arise in long parallel segments of current-carrying wire.
The proximity effect is caused in a wire by the magnetic field from current flowing in nearby parallel wires, such as other loops in the same coil. If two adjacent wires carry a current in the same direction, then the effect is felt in both – the magnetic field of the nearby wires causes current in each wire to be concentrated in a small region on the wire’s surface farthest from the adjacent wires. The concentration of current along a small portion of the conductor increases the wire’s
resistance and hence increases energy loss. At
medium and
high radio frequencies the increased resistance of the inductor can increase the
bandwidth of
tuned circuits and reduce the circuit’s frequency selectivity, or
Q factor.
Parasitic capacitance is the consequence of parallel turns of wire acting as
capacitor plates, storing
charge between adjacent wires. The parasitic capacitance can cause the coil to become
self-resonant at one or several frequencies, which interferes with the intended tuned resonance and blocks and reflects current at the self-resonant frequency. Unfortunately basket-weave coil winding increases the physical size of the coil, which increases
leakage inductance. ==Methods==