Why do exposure limits vary with frequency?

Why do exposure limits vary with frequency?

• A. The human body absorbs more RF energy at some frequencies than at others
• B. The RF radiation disperses more at higher frequencies
• C. Higher frequencies allow less power to be transmitted
• D. The effect of RF radiation is constant regardless of frequency

Answer: (A)

The variation of exposure limits with frequency is primarily due to the fact that the human body absorbs radio frequency (RF) energy differently at various frequencies. This differential absorption occurs because the electrical properties of biological tissues, such as their dielectric constant and conductivity, change with frequency. At certain frequencies, tissues may resonate or absorb energy more effectively, leading to higher potential exposure and physiological effects. For instance, lower frequencies tend to penetrate deeper into the body, while higher frequencies are often absorbed more at or near the surface. Because of this unique interaction, different frequencies can result in varying levels of heat and other biological effects, which necessitates different exposure limits to protect individuals from harm. Understanding this relationship is crucial for ensuring safety in environments where RF energy is present.

The variation of exposure limits with frequency is primarily due to the fact that the human body absorbs radio frequency (RF) energy differently at various frequencies. This differential absorption occurs because the electrical properties of biological tissues, such as their dielectric constant and conductivity, change with frequency. At certain frequencies, tissues may resonate or absorb energy more effectively, leading to higher potential exposure and physiological effects.

For instance, lower frequencies tend to penetrate deeper into the body, while higher frequencies are often absorbed more at or near the surface. Because of this unique interaction, different frequencies can result in varying levels of heat and other biological effects, which necessitates different exposure limits to protect individuals from harm. Understanding this relationship is crucial for ensuring safety in environments where RF energy is present.