26/04/2025
Let's begin. When you hear the term "skin effect," what comes to mind.
Skin effect refers to the tendency of an AC current to distribute unevenly across the conductor’s cross-section, with the current density being highest near the outer surface and gradually decreasing toward the core. Consequently, the inner part of the conductor carries less current compared to the outer regions, which leads to an increased effective resistance of the conductor.
It is essential to note that skin effect does not occur in direct current (DC) systems, as the current in such systems remains uniformly distributed throughout the conductor. However, in alternating current (AC) systems, particularly those operating at high frequencies—such as in radio communication and microwave transmission—the skin effect significantly influences the design and performance of transmission lines and related components.
Now, let's delve into the causes of skin effect in transmission lines.
The skin effect arises due to the interaction between the magnetic field generated by the AC current and the conductor. As AC current passes through a cylindrical conductor, it creates both an external and internal magnetic field. The frequency and amplitude of the AC current determine the behavior of this magnetic field.
According to Faraday’s law of electromagnetic induction, a fluctuating magnetic field induces an electric field within the conductor. This induced electric field, in turn, generates opposing currents, known as eddy currents, inside the conductor. These eddy currents resist the original AC current.
Eddy currents are more concentrated toward the core of the conductor, where the magnetic flux linkage with the AC current is stronger. Conversely, near the conductor's surface, the linkage of magnetic flux is weaker due to the higher magnetic reluctance of air. As a result, stronger opposing electric fields develop within the core, reducing the net current density. Meanwhile, at the conductor’s surface, whe