The Specific Absorption Rate conversion calculator computes the rate at which energy from an electromagnetic field is absorbed by a body or material. It also calculates the incident power density based on electric field strength, material conductivity, and density. This tool is useful for evaluating RF exposure and compliance with safety standards.
Formulas
SAR = (σ * E²) / md
Incident Power Density = E² / 377
Formula Explanation
- σ is the electrical conductivity of the material in siemens per meter (S/m).
- E is the electric field strength in volts per meter (V/m).
- md is the mass density of the material in kilograms per cubic meter (kg/m³).
- SAR represents the rate of RF energy absorption per unit mass, expressed in watts per kilogram (W/kg).
- The constant 377 is the impedance of free space, used to determine the incident power density in watts per square meter (W/m²).
Uses of this calculator
- Evaluating human exposure to electromagnetic fields from wireless devices.
- Testing compliance with SAR limits in RF safety regulations.
- Designing and assessing materials for electromagnetic shielding and absorption.
- Studying RF field effects in biological or dielectric materials.
What is the SAR for an electric field of 50 V/m in a material with 0.8 S/m conductivity and 1000 kg/m³ density?
Input: E = 50 V/m, σ = 0.8 S/m, md = 1000 kg/m³
Output:
- SAR = (0.8 * 50²) / 1000 = (0.8 * 2500) / 1000 = 2000 / 1000 = 2 W/kg
- Incident Power Density = 50² / 377 = 2500 / 377 = 6.63 W/m²
- Specific Absorption Rate = 2 W/kg and Power Density = 6.63 W/m²