Air Core Inductor : Construction, Working, Inductance & Its Applications

An inductor is an electrical component mainly used for storing energy when current flows through it within a magnetic field. Inductors are generally made with a conducting wire by wrapping it into a coil around an inner core where every wire turn is called winding. In an inductor, the number of windings within the coil is related directly to the inductance. There are different types of inductors available where air core inductor is one of the types. This is a nonmagnetic core inductor which is also called an air core coil. These inductors are used in applications where low inductance & high frequency are required. This article discusses an overview of an air core inductor – working with applications.

What is Air Core Inductor?

A type of inductor or a wire coil without a magnetic core in the coil is known as an air core inductor or air coil inductor. In this inductor, an air core ensures a lower peak inductance, however, it also decreases the energy losses associated by means of ferrite inductors. The lack of core losses permits air core inductors to function at maximum frequencies. An air core inductor symbol is shown below.

These types of inductors are utilized whenever the amount of inductance is less required and they do not have a core loss because there is no core. However, the number of turns in this inductor should be more as compared to other inductors which have the core. Generally, ceramic inductors are frequently called air-core inductors. These inductors provide efficient solutions especially for switch mode magnetic requirements when focusing on high frequency, high linearity & reduced core loss.

Construction

The air core inductor’s basic construction is, it consists of coils with a number of wire turns that are wounded on ordinary cardboard. So, ceramics or plastic former may be utilized as an insulating material. In this inductor, the gap in a paper or plastic former works like a core. So this gap has nothing but it has air inside of the former, so known as the air core inductor. Therefore, air works as a core.

Working Principle

These inductors work on the basis that air has a fairly minimum electrical conductivity. So the air-core inductance is also low, producing a weak magnetic field. Because of the small magnetic field generation of air cores’, it achieves a faster current rise while avoiding signal loss. This loss mainly happens whenever an inductor generates high magnetic field strengths within an electric circuit.

Difference b/n Air Core Inductor Vs Solid Core Inductor

The difference between air core inductors and solid core inductors includes the following.

Inductance of Air Core Inductor

The single-layer air core inductor inductance formula can be simply expressed as d2n2/18d+40z.

Where,

‘D’ represents the coil’s diameter.
‘n’ represents the no. of turns within the coil.
‘z’ represents the inductor’s length.
The inductance is simply measured in μH or microhenries..

Advantages & Disadvantages

The advantages of air core inductors include the following.

• The construction of this inductor is very simple.
• These Inductors offer several benefits saturation free, no iron losses, and high-frequency operation.
• It does not depend on the rate of current it carries.
• This inductor also removes the iron losses from the magnetic core.
• At high frequencies, this inductor doesn’t have core losses & distortion.
• This type of inductor is not expensive.
• The slight signal loss occurs at maximum magnetic field strengths.
• An electromagnetic frequency carried by this inductor is up to 1 GHz, however when the frequency goes beyond 100 MHz then ferromagnetic core inductors experience loss.

The disadvantages of air core inductors include the following.

• The size of this inductor is large.
• The Q factor of this inductor is low.
• The high inductance value of these inductors is not possible.
• The number of turns within a coil required to attain the similar inductance that would happen within a solid-core inductor.
• The lower electrical conductivity of air converts to low magnetic permeability & then lower inductance.

Air Core Inductor Applications / Uses

The applications of air core inductors include the following.

• These Inductors are mainly used for designing RF tuning coils.
• These are necessary for different applications like computer devices, electronic devices, TVs, communication devices, mobile chargers, and DVDs.
• These inductors are also employed in snubber circuits, filter circuits & high-frequency-based applications like television and radio receivers.
• This inductor can also be used in low-frequency applications that range from 20 Hz – 1 MHz.
• These are mainly used for interstage coupling.
• These inductors play a key role in designing RF & IF tuning coils.
• It is used to ensure a lower peak inductance, but also reduces the energy losses associated with ferrite inductors.
• These inductors are used in Radio transmitters to reduce the harmonic vibrations when electromagnetic signals travel across them.
• These are used in Hi-fi stereo speakers to ensure minimum sound distortion occurs.

Thus, this is all about an overview of an air core inductor – working with applications. These inductors simply provide effective solutions for switch mode magnetic requirements, particularly when focusing on high frequency, high linearity & reduced core loss. Additionally, these are also ideal solutions once space is not prohibitive. Here is a question for you, what is the function of an inductor?