1. What is the Inverse Square Law?

The inverse square law states that the power density of an electromagnetic wave is proportional to the inverse of the square of the distance from the source. This simplified version calculates the power at a given distance from the transmitter.

2. How Does the Calculator Work?

The calculator uses the inverse square law formula:

Where:

• \( P \) — Power at distance (watts, W)
• \( P_0 \) — Initial power (watts, W)
• \( d \) — Distance from source (meters, m)
• \( \pi \) — Mathematical constant pi (~3.14159)

Explanation: The equation shows how RF power decreases with distance from the transmitter, following the inverse square relationship.

3. Importance of RF Power Calculation

Details: Understanding power distribution is crucial for RF system design, antenna placement, safety compliance, and interference analysis.

4. Using the Calculator

Tips: Enter the transmitter power in watts and the distance in meters. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Is this calculation accurate for all RF scenarios?
A: This is a simplified version that assumes free space propagation. Real-world factors like reflections, absorption, and antenna patterns will affect results.

Q2: What's the significance of the 4π term?
A: This represents the surface area of a sphere, showing how power spreads out uniformly in all directions from a point source.

Q3: How does frequency affect power distribution?
A: While the inverse square law is frequency-independent, higher frequencies experience more atmospheric absorption and diffraction effects.

Q4: Can I use this for near-field calculations?
A: No, the inverse square law applies to far-field radiation (typically distances > 2D²/λ, where D is antenna size).

Q5: How would I calculate power density instead?
A: Power density (W/m²) would be P divided by the area (4πd²), which simplifies to P₀/(4πd²)² in this case.