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Air Core Inductor Coil Inductance Calculator
This calculator estimates the inductance of a single-layer air core coil from coil diameter, coil length, and number of turns. It is useful for RF coils, antenna circuits, filters, oscillators, resonant circuits, and general inductor design.
Input Parameters
Result
The calculation is based on Wheeler's air-core single-layer coil approximation. Accuracy is best when the coil geometry is practical and the winding is relatively uniform.
Equations Used
Air Core Coil Inductance:
L = (d² × n²) / (18d + 40l)
Where:
L = inductance in microhenries (µH)
d = coil diameter in inches
l = coil length in inches
n = number of turns
This formula is commonly used as an approximation for single-layer air core inductors.
Frequently Asked Questions (FAQ)
Q1: What does this calculator do?
It estimates the inductance of an air core coil based on coil diameter, coil length, and number of turns.
Q2: What is an air core inductor?
An air core inductor is a coil without a magnetic core. It uses air as the core material and is common in RF and high-frequency circuits.
Q3: Why does the number of turns matter so much?
Inductance increases approximately with the square of the number of turns, so adding turns can significantly increase inductance.
Q4: Can this calculator be used for RF coils?
Yes. It is useful for estimating RF coils used in filters, resonant circuits, oscillators, antenna networks, and matching circuits.
Q5: Does wire diameter affect the result?
This simplified formula does not directly include wire diameter, spacing, insulation thickness, or self-capacitance. These factors may matter in high-frequency designs.
Q6: Why is this an approximation?
Real inductors are affected by winding pitch, lead length, nearby metal, parasitic capacitance, wire resistance, and construction tolerance.
