sub-GHz Attenuation

Material Interaction

When a radio wave encounters a solid obstacle like a concrete wall or a wooden door, a portion of its energy is absorbed and converted into heat. For sub-GHz attenuation, this absorption is less severe because the longer wavelengths can pass through obstacles that would block higher frequencies. The composition and thickness of the material determine the exact amount of decibel loss.

Dense materials like reinforced concrete or metal-coated glass present a formidable barrier, whereas plasterboard or brick cause minimal signal degradation.

Fading Phenomenon

In outdoor environments, the signal strength decreases with the square of the distance from the transmitter due to free-space path loss. Additional sub-GHz attenuation is introduced by foliage, terrain features and atmospheric moisture. Multi-path propagation occurs when the signal reflects off buildings and ground surfaces, causing the waves to arrive at the receiver at slightly different times.

This can result in destructive interference, which reduces the effective signal-to-noise ratio at the receiver terminal.

Range Consequence

The lower rate of signal loss translates into a much wider coverage area for a given transmitter power. This advantage is exploited in smart metering, agricultural monitoring and industrial automation networks where devices are spread across large distances. Because of the low sub-GHz attenuation, these systems can maintain a stable connection with fewer gateway nodes.

This reduces the infrastructure cost and extends the battery life of the remote sensor nodes by allowing them to transmit at lower power levels.