Evaluating Permissive Change Compliance Paths for Potted RF Transmitter Modules
Adding potting compound to an unpotted RF module demands Class II permissive change re-testing if dielectric loading increases radiated spurious emissions.
SAR Re-Evaluation
Meaning
Specific Absorption Rate assessments are conducted on previously certified wireless devices when a design or usage change modifies the radio-frequency energy absorption in the human body. Performing a SAR re-evaluation determines whether the physical changes to the hardware, or a change in the proximity of the device to the user, require a new compliance filing. It stops applying if the device’s output power is reduced below the level of the original certification.
Exposure Assessment
Measurements are performed using simulated tissue phantoms and high-precision robotically guided probes to measure the internal electric field strength. A SAR re-evaluation is triggered when the antenna is moved closer to the outer casing or when the transmitter’s duty cycle is increased by software. The resulting data are compared with the original filing to see if the absorption rates remain within acceptable safety limits.
This evaluation is necessary to guarantee that the modified device remains safe for close-body operation.
Hardware Modification
Internal changes to the housing material can alter the distribution of the electromagnetic field near the user’s body. If the dielectric properties of the plastic cover change, the absorption profile must be verified.
Compliance Status
Regulatory filings are updated with the new assessment data to maintain the validity of the equipment authorization. This process prevents the suspension of market approval for modified devices.