Meaning
Wireless performance verification relies on a procedure that captures the radiation pattern of a device by rotating it through a full circle within a non-reflective chamber. Performing an anechoic turntable measurement allows engineers to map the three-dimensional gain of an antenna relative to its physical orientation. This process identifies nulls in the signal and confirms that the device meets the regulatory requirements for effective isotropic radiated power.
Angular Resolution
Incremental steps during the rotation determine the granularity of the resulting data set. Because a high angular resolution provides a clearer picture of narrow side lobes, it often requires more time to complete a full sweep. High precision is necessary when the board layout involves metallic enclosures that might deflect radio energy.
Signal Consistency
Stable RF transmission during the entire rotation ensures that the collected data reflects the antenna performance rather than hardware fluctuations. If the anechoic turntable measurement happens while the battery voltage drops, the power output might sag and invalidate the test results. A constant power source usually replaces the battery to maintain a steady reference during the long measurement cycle.
Positional Accuracy
Mechanical drift in the motor or slippage of the mounting fixture can introduce errors into the spatial mapping. The positional accuracy of the equipment determines if the measured peak gain aligns with the physical boresight of the antenna. Reliable fixtures hold the device under test at the exact center of rotation to prevent phase center offsets.
Maintaining the alignment requires periodic calibration against a reference dipole antenna to ensure the rotational center remains stable. Accurate positioning ensures that the gain measurements remain repeatable across different test batches.
