Radio waves are electromagnetic radiation used for global communication, but can be blocked by natural phenomena and certain materials. They are harmless to humans and can be intentionally or accidentally blocked. Transmittance and attenuation coefficient determine the ability of materials to block radio waves, while diffraction depends on the wavelength and size of obstacles.
Radio waves are a type of electromagnetic radiation and the primary mode of global communication. In addition to radio broadcasting, other applications such as televisions, cell phones, and radio-controlled cars all use forms of the technology. The challenge with this form of communication is the fact that different natural phenomena such as mountains, together with certain materials such as copper and aluminum can block the waves.
As a simple form of electromagnetic radiation, radio waves are harmless to humans and travel from place to place with little impact. The advantages and disadvantages of blocking radio waves come in the form of intentional or accidental events. A military may choose to block an enemy’s radio waves, for example. Other situations involve the natural interruption of a transmission.
To understand what blocks radio waves, it is necessary to explain the fundamental theory behind the technology. A radio signal is sent from one location via a device known as a broadcast antenna, basically creating an electromagnetic field that is projected from the unit to the wider world. Each wave travels in every direction until it hits a receiving antenna, a device designed to pick up the wave.
Transmittance is the theory that makes radio waves travel through materials without being stopped. Either a material is a good or bad transmitter of radiation. An example of a good transmitting material is the Earth’s lower atmosphere, which allows radiation to travel long distances. The same cannot be said for the upper layer of the atmosphere, however, which is known as the ionosphere. This contains ionized radiation from the sun, which reflects radio waves back to the lower atmosphere.
The attenuation coefficient is the level to which a material will block or interfere with radio waves. This coefficient strongly depends on the thickness and composition of the material. Cardboard, paper, many plastics, water and glass are all substances with very low attenuation coefficients. Wood, brick and concrete have a limited effect on radio waves. Metal compounds, reinforced concrete, and the earth reflect signals, however, blocking the passage of radio waves.
An important consideration that determines whether radio waves are blocked involves the concept of diffraction. This depends on the wavelength of the radiation and the size of the obstacle it is trying to penetrate. Low frequencies have an easier time passing over large objects like hills, while higher frequencies work better with small obstacles like roofs. This can be very useful for blocking radio waves using the knife diffraction method. If a wave does not have line of sight to an object, a sharp edge can be created causing the wave to be blocked and redirected to where the transmission should go.
Protect your devices with Threat Protection by NordVPN
