Meaning
Physical signal attenuation occurs when a wireless device is operated near human tissue. Phantom body loss accounts for the energy absorbed by a user, which reduces the effective radiated power.
Absorption Rate
Water and salt in the human body are highly effective at absorbing radio frequency energy at cellular and wi-fi frequencies. During testing, phantom body loss is measured using a plastic shell filled with a liquid that mimics the electrical properties of human flesh. This simulation provides a repeatable way to see how much of the signal is blocked or redirected by the person holding the device.
Antenna Tuning
Proximity to a body changes the impedance of the antenna, often pulling it away from its resonance point. Engineers must account for phantom body loss by designing antennas that are less sensitive to their surroundings or by adding matching circuits that adjust to the presence of a user. A well-tuned system minimizes the impact of this absorption to keep the link stable.
Certification Margin
Regulatory bodies set limits on how much energy the body can absorb while requiring a minimum level of performance. Designers use phantom body loss data to ensure the device remains compliant with safety standards while still having enough power to reach a distant base station. High losses in this area can lead to dropped calls or slow data speeds when the device is used in a typical handheld position.
