 Figure 1.2: Radio Wave Propagation PhenomenaRadio waves can travel in different ways between a transmitter and a receiver.
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 Figure 1.3: Light Wave Propagation Phenomena Is quite similar to Radio Wave Propagation. The key difference is that light waves are more easily affected by obstacles and atmospheric conditions due to their shorter wavelength. |
The diagrams above focus on five key properties of wave propagation:
- Free space is the ideal scenario where the radio waves travel directly from the transmitter to the receiver without any obstacles. We often refer to this as line of sight (LOS) propagation.
- Diffraction is the phenomenon where radio waves bend around obstacles, allowing them to reach areas that would otherwise be shadowed. This is particularly important in urban environments where buildings can obstruct the direct path between the transmitter and receiver.
- Scattering occurs when radio waves encounter objects or irregularities in the propagation medium (such as trees or buildings), causing them to be scattered in different directions. This can lead to signal fading and fluctuations in signal strength.
- Reflection is the process where radio waves bounce off surfaces, such as buildings or the ground. Reflected waves can reach the receiver via indirect paths, leading to multipath propagation and potential signal interference.
- Refraction: Skywaves refract i.e. bend and reflect off the ionosphere due to changes in free electron density, enabling long-distance communication beyond the horizon.
Additional properties of waves
- Polarization: Electric field orientation.
- Rays: Wave propagation direction.
- Wavefronts: Surfaces of constant phase.
- Field Intensity: Strength of the wave's field.
- Power Density: Power per unit area.
- Path Loss: Signal weakening over distance, caused by free-space loss, refraction, diffraction, reflection, aperture-medium coupling loss, and absorption. It’s also affected by terrain, environment, propagation medium, distance between transmitter and receiver, and antenna height and location.
- Signal-to-Noise Ratio (SNR)
: A measure used to compare the level of a desired signal to the level of background noise. It's calculated as the ratio of the power of the signal to the power of the noise, often expressed in decibels (dB). The higher the SNR, the clearer and more distinguishable the signal is from the noise.
- Spectrum
: a property of waves describing the range of frequencies or wavelengths. Spectroscopy studies the spectra of electromagnetic radiation by measuring its wavelength or frequency with specialized equipment to understand matter's structure and properties.
Light and radio waves are both forms of electromagnetic radiation, differing in their wavelengths and frequencies. Light waves, which have shorter wavelengths and higher frequencies, are visible to the human eye and allow us to perceive color. They can be emitted by sources like the sun and artificial light bulbs. In contrast, radio waves have longer wavelengths and lower frequencies, making them ideal for long-distance communication. They are used for broadcasting radio and television signals, as well as for wireless communication technologies such as Wi-Fi and Bluetooth.
Back to the main page: Ionosphere radio wave propagation.
See also an index of terms for HF Radio Propagarion.
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