Meaning
Global regulatory frameworks restrict the maximum radiated power of wireless transmitters to prevent interference between devices. These regulatory power limits, known as antenna gain constraints, restrict the amplification factor of the antenna connected to a pre-approved radio module. Exceeding these limits can invalidate the equipment authorization and lead to legal penalties.
Designers must carefully select antennas that do not exceed the specified gain values across all operational bands.
Radiation Limit
Wireless regulators define the maximum equivalent isotropically radiated power permitted for specific frequency bands. This total power combines the transmitter output power and the antenna gain, minus any cable losses.
Certifiable Configuration
Modular approvals depend on testing the radio with a specific antenna type and maximum gain. Changing to a higher gain antenna usually requires a Class II permissive change or complete re-certification of the final assembly. The certification path remains simple only when the chosen antenna stays below the specified antenna gain constraints.
Decibel Compliance
Antenna performance is measured in decibels relative to an isotropic radiator, which represents the directional amplification of the signal. This unit allows straightforward arithmetic to calculate the total radiated energy of the system. Systems that operate within these bounds maintain compliant operation without requiring costly laboratory re-testing.
This direct calculation is verified during the final factory inspection before the product ships.
