Meaning
Radiofrequency metrics characterize the level of signal distortion caused by multi-path interference in test chambers. In electromagnetic compatibility testing, svswr evaluates the performance of a test site at frequencies above one gigahertz by measuring the ratio of constructive to destructive interference. It is calculated from signal sweeps along specified paths using a moving antenna.
This ratio indicates whether the chamber meets standard requirements for emission testing, and it is a fundamental requirement for labs performing compliance tests on modern communication devices.
Measurement Sweep
The evaluation involves moving a transmitter along a straight path while measuring the signal level at a fixed receiver position. This movement is done at multiple heights and polarization states. The resulting data shows the peak-to-peak variation of the signal.
Reflection Source
Reflections from the chamber floor, walls, and positioning system are the primary source of high svswr values. These reflections are caused by poor performance or deterioration of the absorber material. Adding higher-performance absorbers in the reflection paths lowers the ratio.
Compliance Level
Standard documents like CISPR 16 specify a limit of six decibels for the test volume to be deemed acceptable. Chambers with values below this limit are approved for compliant emission testing. Maintaining this level is necessary for international product certification.
