Boundary Interaction
Wave phenomena occur when a signal encounters a boundary or a sharp corner in its path. Edge diffraction causes electromagnetic or acoustic waves to bend around the perimeter of an object. The effect is most pronounced when the obstacle has dimensions comparable to the wavelength of the signal.
Physical Distortion
Secondary wavelets are created that interfere with the primary signal and produce patterns of constructive and destructive interference. In high frequency sensing, edge diffraction can lead to false readings or phantom targets. The strength of the effect depends on the relationship between the wavelength and the size of the obstacle.
Sharp metal edges are particularly prone to scattering energy in unintended directions.
Sensor Modeling
Engineers use numerical simulations to predict how waves will behave near the boundaries of a transducer. Understanding edge diffraction is necessary for designing effective shielding and aperture plates. Finite element analysis provides a way to visualize the fringe fields that form at the corners of a sensor.
By rounding the edges or using absorbent materials, the impact of the scattered waves can be reduced.
Metrological Impact
Accuracy is lost when the diffracted waves overlap with the desired measurement pulse. Edge diffraction is often the limiting factor in the resolution of ultrasonic or radar based ranging systems.
