Meaning
Computational method used to calculate the far field radiation pattern of an antenna from measurements taken close to the source. Near field reconstruction enables engineers to characterize the performance of high frequency devices in smaller test chambers. This technique transforms spatial data captured on a planar or spherical surface into a directional plot.
It relies on the mathematical relationship between different regions of electromagnetic propagation.
Measurement Protocol
Probe stations scan the area immediately surrounding the device under test to collect phase and amplitude information. During near field reconstruction, the software accounts for the distance and orientation of the measurement probe. This step is necessary to remove the influence of the probe itself from the final results.
Precise positioning of the robotic arm is required to maintain the integrity of the data.
Hardware Qualification
Antenna modules for 5G applications are often tested using these methods to ensure they meet gain and beamwidth specifications. Near field reconstruction provides a detailed map of the electromagnetic field before the waves fully form into a plane wave. This information helps in identifying surface currents or leaking signals from the board traces.
Manufacturers use this data to refine the layout of the RF section.
Data Accuracy
Sampling density and measurement distance are the primary factors affecting the quality of the output. If the probe is too far or the samples are too sparse, the near field reconstruction will lose high frequency components. Advanced algorithms compensate for noise in the measurement environment to improve the reliability of the far field prediction.
Final validation involves comparing these results with traditional outdoor range tests.
