Meaning
Distortions that occur when a spatially continuous signal is sampled at too few points across an area lead to incorrect representations of the underlying wave or surface. The presence of spatial aliasing causes high-frequency spatial variations to appear as lower-frequency patterns in the reconstructed dataset. This phenomenon occurs when the distance between measurement points is greater than half the wavelength of the highest spatial frequency present.
It commonly affects phased array antennas and digital imaging sensors.
Sensor Pitch
The distance between adjacent sensor elements in an array determines the maximum spatial frequency that can be resolved. To prevent spatial aliasing, the sensor pitch must be designed to be sufficiently small to capture the shortest expected wavelength. A larger spacing results in ambiguous measurements where different signal angles produce identical output patterns.
This spacing is a fundamental design constraint for acoustic arrays.
Nyquist Limit
Sampling theory dictates that the spatial sampling rate must exceed twice the highest spatial frequency of the target field. In systems prone to spatial aliasing, this boundary is known as the spatial Nyquist limit. Failing to meet this criterion means that fine details are permanently lost or folded back as spurious low-frequency artifacts.
The resulting data is mathematically impossible to correct after sampling has occurred.
Antialiasing Filter
Physical barriers or optical diffusers can be placed in front of a sensor array to limit high-frequency components. Spatially filtering the signals avoids spatial aliasing entirely.
