What is used for measuring gain on a Wi-Fi antenna?

The correct answer isBbecause Wi-Fi antenna gain is expressed usingdBi, which means decibels relative to an isotropic radiator. Cisco’s Wireless RF Reference Guide states that antenna gain is measured in decibels relative to isotropic gain, ordBi. Cisco RF design documentation also explains that dBi is used to describe the power gain rating of antennas by comparing real antennas against an ideal isotropic antenna that radiates equally in all directions.

Antenna gain is not a measurement of physical antenna length. Length may influence antenna design and resonance, but it is not the operational unit used to express gain. It is also not measured as voltage against dBm.dBmis an absolute power reference relative to one milliwatt, commonly used for transmit power or received signal strength, whiledBidescribes antenna gain. Cisco’s EIRP calculation reinforces this separation: transmitter power is in dBm, antenna gain is in dBi, and cable loss is in dB. A “blend of analog and digital signals” has no RF measurement relevance. Reference topic:RF Fundamentals — antenna gain, dB/dBi/dBm, isotropic radiator reference, EIRP, and RF propagation behavior.