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Dipole Antenna Formula:
Where:
L = Dipole length in feet
f = Frequency in MHz
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A dipole antenna is the simplest and most widely used type of radio antenna. It consists of two identical conductive elements such as metal wires or rods, which are bilaterally symmetrical.
The calculator uses the dipole antenna formula:
Where:
Explanation: The formula calculates the total length of a half-wave dipole antenna for a given frequency. The number 468 represents the speed of light multiplied by a velocity factor for typical wire antennas.
Details: Proper antenna length is crucial for efficient radio wave transmission and reception. An antenna that's too long or too short for the operating frequency will have poor performance.
Tips: Enter the desired operating frequency in MHz. The calculator will give you the total length of the dipole antenna in feet. For best results, divide this length equally between the two sides of the dipole.
Q1: Why 468 instead of 492?
A: The number 492 would be for a half-wavelength in free space (984/f). The 468 factor accounts for the velocity factor of typical wire antennas (about 95% of light speed).
Q2: Should I cut the antenna exactly to this length?
A: This gives you a good starting point, but you may need to fine-tune the length for optimal SWR at your specific location.
Q3: Does this work for all frequencies?
A: The formula works well for HF and VHF frequencies. At UHF and higher, other factors become more significant.
Q4: What if I want the length in meters?
A: To convert feet to meters, multiply by 0.3048. Or use the metric formula: L = 142.65 / f (where L is in meters).
Q5: Can I use this for vertical antennas?
A: For a quarter-wave vertical, divide the dipole length by 2 (234/f in feet).