Meaning
Mathematical technique that calculates the complete three-dimensional electromagnetic field of an antenna from a limited set of physical measurements taken in the near field. For millimeter-wave device testing, radiation field reconstruction allows engineers to determine the far-field antenna pattern without using a full-sized anechoic chamber. This computational method is valid only when the input measurement data captures both the amplitude and the phase of the fields.
Chamber Efficiency
Measuring far-field performance directly requires large, expensive testing facilities. Utilizing radiation field reconstruction reduces the required size of the test chamber, which lowers the capital cost of the equipment. This approach allows factories to integrate antenna testing directly into the production line.
Numerical Method
Equivalent source algorithms are used to model the antenna as a set of virtual currents on a closed surface. These algorithms use the measured near-field data to solve for the virtual currents, which are then used to perform the radiation field reconstruction at any distance. This method must account for the probe’s own influence on the field to prevent measurement errors from distorting the calculated pattern.
Design Evaluation
Multi-antenna systems can be evaluated quickly using these mathematical models during the development phase. The reconstructed field shows how the radiation pattern interacts with the device enclosure and internal components. This feedback helps engineers optimize the placement of the antennas and the design of the plastic casing to avoid blocking the signal and to improve the overall wireless performance.
It also allows them to identify any unwanted surface waves that might be propagating along the metal edges of the device chassis.
