Meaning
Performance metric quantifying the quality of an anechoic chamber by measuring the standing wave ratio across a specified test volume. Maintaining a low site vswr ensures that reflections from the walls and floor do not corrupt the measurement of the device under test. This parameter is a standard part of chamber validation according to international testing requirements.
It does not measure the impedance of the antenna itself but the reflection characteristics of the entire facility.
Chamber Validation
Regular testing with a reference antenna confirms that the absorber material is still performing according to the original specifications. If the site vswr increases over time, it indicates that the absorbers may be damaged or that new metal objects have been introduced into the room. This verification is essential for maintaining the accreditation of the laboratory.
Reflection Loss
Unwanted signals bouncing off the surfaces of the chamber create interference patterns that lead to inaccurate gain and emission data. A high site vswr value means that these reflections are significant enough to impact the results. Engineers use this data to identify the specific areas of the chamber that require additional shielding.
Test Repeatability
Consistency between different test sessions depends on a stable environment with minimal reflections. By achieving a low site vswr, the laboratory ensures that the data collected today will match the data collected in the future. This repeatability is a hallmark of a high quality testing facility.
