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Antenna Size Formula:
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Antenna size calculation determines the optimal length of an antenna based on the wavelength of the radio frequency it's designed to transmit or receive. The most common antenna sizes are quarter-wave (λ/4) and half-wave (λ/2) antennas.
The calculator uses the antenna size formula:
Where:
Explanation: The antenna length is directly proportional to the wavelength of the signal. Quarter-wave antennas are λ/4 long, while half-wave antennas are λ/2 long.
Details: Proper antenna sizing is crucial for efficient signal transmission and reception. An antenna that's the correct length for its operating frequency will have better performance, impedance matching, and radiation efficiency.
Tips: Enter the wavelength in meters and select the antenna type (quarter-wave or half-wave). The wavelength can be calculated from frequency using the formula: λ = c/f, where c is the speed of light (3×10⁸ m/s) and f is frequency in Hz.
Q1: What's the difference between quarter-wave and half-wave antennas?
A: Quarter-wave antennas are shorter and typically require a ground plane, while half-wave antennas are longer but often have better performance and don't require a ground plane.
Q2: How do I calculate wavelength from frequency?
A: Use the formula: wavelength (λ) = speed of light (3×10⁸ m/s) ÷ frequency (Hz). For example, for 100 MHz: λ = 300,000,000 / 100,000,000 = 3 meters.
Q3: Are these calculations exact?
A: These are theoretical calculations. Actual antenna lengths may need slight adjustments due to factors like antenna diameter, nearby objects, and velocity factor.
Q4: Can I use this for any frequency?
A: Yes, the formula works for any frequency, but practical considerations like antenna size and material properties may limit very high or very low frequency applications.
Q5: What about other antenna types?
A: While quarter-wave and half-wave are common, other antenna types (full-wave, fifth-wave, etc.) use different length ratios and may have different radiation patterns.