Air Core Flat Spiral Inductance Calculator

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The flat spiral air core inductor holds a prominent place, finding its application in various devices like Tesla generators, RFID tags, and proximity detectors. These inductors come in different planar spiral coil designs, such as square, rectangular, hexagonal, and octagonal, often used in high-frequency applications and integrated onto PCB as tracks.

The advantages of air core inductors are numerous, including a higher Q-factor, improved efficiency, enhanced power handling, and reduced distortion. However, they require more turns or larger coil sizes to attain a specific inductance value, leading to larger physical dimensions, lower self-resonance, and higher copper loss. Additionally, they may generate more stray field radiation and be more susceptible to external pickups.

Understanding Air Core Flat Spiral Inductance:

Design and Uses: These inductors are commonly found in proximity detectors, RFID tags, and the main of Tesla generators. In addition, they are present in resonant circuits, low pass filters, antenna matching units, crystal sets, antenna traps, wireless charger designs, and crystal sets.

Air Core Inductors:Air core inductors employ air as the core, as opposed to inductors wound on a bobbin constructed of ferromagnetic materials. This indicates that their inductance is independent of the current they carry and that they lack the ferromagnetic core characteristic of non-linearity in the magnetization curve. 

Advantages and Disadvantages: Because they don’t have core saturation and are linear, air core inductors are useful in some situations. To get a given inductance value, they need more and/or larger turns, though, which might result in larger coils, lower self-resonance, and higher copper loss at higher frequencies.

Calculators: Use the online calculator below to assist in designing your next pancake-shaped flat spiral air core coil inductor. Inputs such as inductance, inner diameter, wire diameter, number of turns, and distance between windings are usually needed for these computations. 

Understanding Air Core Flat Spiral Induction:

Characteristics: Several features distinguish Air Core Flat Spiral Inductors from conventional inductors: 

Inductance is unaffected by current: Air Core Flat Spiral Inductors do not see a change in inductance in response to variations in current, in contrast to ferromagnetic core inductors.

No core loss: There is no core loss or energy loss from magnetic saturation because there is no ferromagnetic material present. 

Higher self-resonance: Because of the interwinding capacitance, Air Core Flat Spiral Inductors often have a higher self-resonance frequency.

Larger coils required: Air Core Flat Spiral Inductors frequently need more turns and larger coils to obtain a given inductance value, which might increase copper loss. 

Design Considerations: The following elements must be taken into account while building an Air Core Flat Spiral Inductor: 

Inner diameter:The self-resonance frequency and inductance value are influenced by the coil’s inner diameter. 

Distance between windings: The self-resonance frequency and inductance value are influenced by the spacing between windings. 

Wire diameter: Copper loss and the inductance value are influenced by the wire diameter. 

Number of turns: The self-resonance frequency and inductance value are influenced by the number of turns. 

Advantages: Air Core Flat Spiral Inductors have a number of benefits, such as:

High frequency operation: They don’t have a lot of core loss when operating at high frequencies. 

Low power loss: Because there is no core loss, they have minimal power loss.

Compact design: They could be made to be lightweight and tiny. 

Disadvantages:Additionally, Air Core Flat Spiral Inductors have a few drawbacks, such as: 

Higher cost: The cost of manufacturing them may be higher than that of conventional inductors. 

Limited inductance range: They might not be appropriate for uses where large inductance values are necessary. 

Sensitivity to environmental factors: They may be susceptible to changes in humidity and temperature in the surrounding air. 

In conclusion, air-core flat spiral inductors are a special kind of inductor that have a number of benefits, such as compact design, minimal power loss, and high frequency operation. They do, however, have certain drawbacks, including increased cost and a shorter inductance range. Design considerations and performance-influencing aspects must be taken into account while creating an Air Core Flat Spiral Inductor. 

Outer diameter (d1)
mm
Inner diameter (d2)
mm
Number of turns (N)
Formula:
\[Air \;Core\; Flat\; Spiral\; Inductance = \frac {(4.921 * N^2(d_1 + d_2)^2)}{(15d_1 – 7d_2)} * dimension\]

where :

  • N = the number of turns
  • d1=outer diameter
  • d2=inner diameter
  • If the dimension unit is mm, then dimension = 1. if the dimension unit is mils then the dimension is 0.0254

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