Meaning
Vertical calibration planes in an anechoic chamber establish the boundaries within which the generated electric field is highly uniform. A uniform field area is this defined region, typically measuring one and a half meters square, where the field variations must not exceed the limits specified by international standards. This region is where the equipment under test is positioned during radiated immunity testing.
Field Integrity
Quality of the test field is determined by the design of the chamber’s absorbers and the performance of the transmit antenna. Within the uniform field area, the electric field strength must be consistent to ensure that all parts of the device are exposed to the same level of stress. This consistency is critical for obtaining reproducible test results.
Setup Optimization
Transmitter positioning and height adjustments align the beam with the target zone. When calibrating the uniform field area, a grid of sensors measures the field strength at multiple points to confirm that the variation remains within a six-decibel range. This measurement is repeated for both horizontal and vertical polarizations.
If the field is non-uniform, the positioning of the antenna or the placement of absorbers on the chamber floor must be modified to correct the distortion.
Standard Verification
Compliance with international testing standards requires periodic validation of the field’s uniformity. By documenting that the uniform field area meets the requirements of IEC 61000-4-3, the laboratory demonstrates its capability to perform high-quality immunity tests. This validation is a key requirement for maintaining laboratory accreditation.
