Calculating Volumetric Site Voltage Standing Wave Ratio in Hybrid Chambers
Volumetric site voltage standing wave ratio in hybrid chambers isolates 3D quiet zone reflections by converting normalized spatial field ripples into linear ratios.
Directivity Normalization
Meaning
Calibration algorithms in antenna measurement systems mathematically remove the directional bias of the reference probe. When evaluating a device under test, directivity normalization ensures that the recorded gain pattern reflects only the radiation properties of the target module. This step isolates the performance of the integrated transmitter from the test enclosure effects.
Reference Antenna
Reference horns are mapped in a quiet chamber to establish a baseline radiation pattern. This known pattern of directivity normalization allows the test system to cancel out the gains and losses of the measurement path. Technicians perform this task before mounting the product to be tested on the rotation stage.
The resulting database of antenna coefficients is saved for use in all subsequent test runs. This reference database must be updated if any coaxial adapter or cable in the system is replaced.
Software Correction
Digital processing software processes the raw power measurements received during the angular scan. Application of directivity normalization translates these raw voltage readings into absolute gain values across three dimensions. This algorithm must run in real time to prevent processing bottlenecks during high-throughput factory testing.
Accurate execution of this script is critical for certifying the integrated antenna arrays.
Measurement Error
System errors propagate through the final results if the reference baseline is established using a worn or misaligned cable. Incorrect directivity normalization creates artificial side lobes in the measured radiation pattern of the wireless module. Such errors can lead to the false rejection of a properly assembled device during final quality assurance checks.