Knowledge

In areas where the terrain is complex and short-wave ground waves or line-of-sight microwaves are blocked and cannot be reached, communication can be achieved by using sky waves pr

The earliest human understanding of electromagnetic waves was in the field of optics. Many famous physicists in history have explored the nature of light, among them the great scie

Ultraviolet light is outside the violet light in the spectrum and is invisible light. Sunlight is rich in ultraviolet rays. When the right number of ultraviolet rays irradiate the

Medium wave (frequency 300kHz-3MHz) is mainly propagated by ground waves, but its high section can also be reflected by the ionosphere at night and is mainly used for broadcasting

The original radio signals were transmitted in the form of Morse code, because Morse code encodes English letters and numbers into two states of dots and horizontal lines, which is

To conduct radio communication, first of all, radio waves are emitted. In a radio wave transmitter, there is an important component called an oscillator, which can generate a high-

According to the definition of the International Telecommunication Union (International Telecommunication Union), radio (Radio) is a general term used for radio waves (Radio Waves)

Meter wave (frequency 30MHz-300MHz), decimeter wave (frequency 300MHz-3GHz) and centimeter wave (frequency 3GHz-30GHz) are usually called ultrashort waves or microwaves. They are r

Yes, visible light is the portion of the electromagnetic spectrum that the human eye can perceive. There is no precise range of the visible spectrum; the average human eye can perc

Infrared and shorter wavelength electromagnetic waves are beyond the scope of radio waves, but they are closely related to radio, so they are introduced here by the way. Infrared (

Electromagnetic waves are electromagnetic fields that propagate in waves. In free space, it consists of electric and magnetic fields whose magnitudes are proportional and perpendic

From extremely long wave (frequency 3Hz-30Hz) to even long wave (3kHz-30kHz), it mainly propagates long distances along the earth's surface (also known as ground wave propagati