1. What is the Far Field Equation?

The Far Field equation calculates the far field distance for an antenna based on the antenna's largest dimension (D) and the wavelength (λ). This distance marks the boundary where the radiation pattern becomes stable and the wavefront approximates a plane wave.

2. How Does the Calculator Work?

The calculator uses the Far Field equation:

Where:

• \( D \) — Largest dimension of the antenna (m)
• \( \lambda \) — Wavelength (m)

Explanation: The equation determines the minimum distance from the antenna where the far field region begins, characterized by stable radiation patterns and minimal reactive field components.

3. Importance of Far Field Calculation

Details: Accurate far field calculation is essential for antenna testing, measurement setups, and ensuring proper antenna performance evaluation in free-space conditions.

4. Using the Calculator

Tips: Enter the largest dimension of the antenna (D) in meters and the wavelength (λ) in meters. Both values must be positive numbers greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between near field and far field?
A: Near field is close to the antenna where reactive fields dominate, while far field is where radiative fields dominate and radiation patterns are stable.

Q2: Why is the 2D²/λ formula used for far field?
A: This formula provides a conservative estimate for the beginning of the far field region where antenna measurements are most accurate.

Q3: How is wavelength related to frequency?
A: Wavelength (λ) = speed of light (c) / frequency (f), where c ≈ 3×10⁸ m/s.

Q4: Does this formula apply to all antenna types?
A: While generally applicable, some specialized antennas may have different far field criteria based on their specific radiation characteristics.

Q5: What are typical far field distances for common antennas?
A: Far field distances vary significantly based on antenna size and frequency, ranging from centimeters for small antennas to kilometers for large radar antennas.