What is Electromagnetic Wave??? In electronics theory, when current flows through a conductor, a magnetic field is formed around the conductor; when an alternating current passes through the conductor, an alternating electromagnetic field is formed around the conductor, which is called electromagnetic wave.
When the electromagnetic wave frequency is lower than 100khz, the electromagnetic wave will be absorbed by the surface and cannot form effective transmission, but when the electromagnetic wave frequency is higher than 100khz, the electromagnetic wave can propagate in the air and be reflected by the ionosphere at the outer edge of the atmosphere to form long-distance transmission capability.
We call the high-frequency electromagnetic wave with long-distance transmission capability as radio frequency, the English abbreviation: RF. High-frequency circuits are basically composed of passive components, active devices and passive networks. The frequency characteristics of components used in high-frequency circuit boards are different from those used in low-frequency circuits. Passive linear components in high-frequency circuits are mainly resistors (devices), capacitors (devices) and inductors (devices).
