Air Core Inductor Coil Inductance CalculatorĪdvantages of an air core coil: Its inductance is unaffected by the current it carries. Some others are wound on a bobbin made of bakelite, plastic, ceramic etc. Some inductors are wound without a bobbin and just air as the core. More about air core inductors What is an air core inductor? An "air core inductor" is an inductor that does not depend upon a ferromagnetic material to achieve its specified inductance. Other combinations of wire and coil diameter may be tried but best results are usually obtained when the length of the coil is the same as its diameter. Small reductions in the inductance obtained can be achieved by pulling the turns apart slightly. The diameter is measured from center of wire trough center of the coil and to center of the wire on the opposite side. Roger Green.D is the coil diameter in meters. Diameter is how wide the coil is and length is how long the coil is. The coil diameter uses the mean diameter of the copper coil. Learn how your comment data is processed. Please complete some simple maths to prove you are a human! Your email address will not be published. The wire was some common copper ground wire I picked up at a local hardware store. The other calculators I tried online were estimating from 2. My first calculations were less but when I measured it I got 3. My SWR was good without but I wanted to get rid of some unwanted wind noise on digital modes in the especially in the 20 meter band. I ran some numbers when designing the shunt for my HiQ antenna and found yous to be more accurate than others. It is an error larger than the diameter of an electron, but I think I can live with your formula! I just came across this site. The true length of the line is the length of the hypotenuse of the triangle formed from the true circumference and the turn spacing. It is false precision in the wire length because the length depends on the Turns Per Inch as well. I love the idea that you have Pi to 50 digits. My mean diameter is roughly Is it possible to add a field for the copper wire diameter? And use that to calculate the coil resistance in ohms? The bit over is the uncoiling that naturally occurs when one releases the tensioning force. A 1mm wire wound on a 14mm bobbin will have a mean diameter a bit over 15mm. Just remember to cut a bit longer for some tails! I never use thick enough wire to worry, but I would use the inside diameter. As 39 decimal places is sufficient to estimate the circumference of any circle that fits in the observable universe with precision comparable to the radius of a hydrogen atom, the 50 decimal places I have used should be OK for your inductor. Frequency can be entered to find the Q of the inductor at a specific frequency, but is not required.Īn example of a T-match inductor for 1.
Build a pH Meter and Controller.This calculator is useful when making antenna matching units, low pass filters, crystal sets, antenna traps, resonant circuits or anywhere where an air cored single layer inductor is required.ĭiameter and length of inductor are entered in millimetres along with the number of turns.
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Inductance of Air Core Inductor Calculatorĭipole Antenna Length. Small Transmitting Loop Antennas.įull-Wave Loop Antennas. Inches Centimeters Single-layer coil Multi-layer, multi-row coil Multi-layer, single-row coil The following inductance formula requires units in inches. Enter the coil length distance from first to last winding - see diagram. Select the measurement units inches or centimeters. Coil Inductance Calculator To calculate the inductance of a single-layer, air-core coil: 1.