// Definition and Effect of Reflection, Diffraction, Scattering and Multipath Propagation in RF Engineering

# Definition and Effect of Reflection, Diffraction, Scattering and Multipath Propagation in RF Engineering

## Definition and Effect of Reflection, Diffraction, Scattering and Multipath Propagation in RF Engineering

### Reflection Diffraction and Scattering in wireless communication

When any new site has been planned then it should be such a way the effect of Reflection, Diffraction, Scattering and Multipath should be Balance.

## Reflection in wireless communication

• Reflections Occurs when a wave impinges upon a smooth surface.
• Dimensions of the surface are large relative to l.
• Reflections occur from the surface of the earth and from buildings and walls.

## Diffraction in wireless communication

• Diffraction Occurs when the path is blocked by an object with large dimensions relative to l and sharp irregularities (edges).
• Secondary “wavelets” propagate into the shadowed region.
• Diffraction gives rise to bending of waves around the obstacle.

## Scattering in wireless communication

• Scattering Occurs when a wave impinges upon an object with dimensions on the order of l or less, causing the reflected energy to spread out or“scatter” in many directions.
• Small objects such as street lights, signs, & leaves cause scattering

MultiPath in wireless communication

• Multiple Waves Create “Multipath”
• Due to propagation mechanisms, multiple waves arrive at the receiver
• Sometimes this includes a direct Line-of-Sight (LOS) signal

## Multipath Propagation in wireless communication

• Multipath propagation causes large and rapid fluctuations in a signal
• These fluctuations are not the same as the propagation path loss.

Multipath causes three major things in wireless communication

• Rapid changes in signal strength over a short distance or time.
• Random frequency modulation due to Doppler Shifts on different multipath signals.
• Time dispersion caused by multipath delays
• These are called “fading effects
• Multipath propagation results in small-scale fading.

Now you understand diffraction has what affect on a wireless signal’s propagation?.