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# Far-Field Calculator – Determine Far-Field Distance for Antennas

The Far-Field Calculator is a helpful tool for engineers and technicians working with antennas, providing a way to determine the far-field distance, an essential parameter in antenna measurements. This article will explain how the calculator works, the formulas it uses, and how to use it to obtain accurate measurements.

## The Far-Field Distance Concept

When working with antennas, it is crucial to understand the far-field distance, which is the region where the antenna’s radiation pattern becomes stable and essentially independent of distance. This is the area where the electromagnetic field emitted by the antenna can be considered as a plane wave. Performing antenna measurements, such as gain or radiation pattern, should be done in the far-field region to ensure accurate and repeatable results.

## The Far-Field Calculator Formula

The calculator uses the following formula to determine the far-field distance:

Far-Field Distance (m) = (2 * Antenna Diameter²) / Wavelength

• Far-Field Distance: The minimum distance from the antenna where the far-field region begins.
• Antenna Diameter (m): The largest linear dimension of the antenna, usually its longest side or its aperture.
• Wavelength (m): The wavelength of the electromagnetic wave, determined by dividing the speed of light by the frequency of the wave.

## Using the Far-Field Calculator

Using the Far-Field Calculator is straightforward. Simply enter the wavelength and antenna diameter values, and the calculator will provide the far-field distance. For example, let’s assume we are working with an antenna with a diameter of 1 meter and a frequency of 3 GHz.

1. Convert the frequency to wavelength: Wavelength = Speed of Light / Frequency = (3 * 10^8 m/s) / (3 * 10^9 Hz) = 0.1 meters
2. Input the wavelength (0.1 m) and antenna diameter (1 m) into the calculator.
3. The calculator will provide the far-field distance: (2 * 1²) / 0.1 = 20 meters