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Half Wave Dipole Formula:
Half wave in feet.
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A half-wave dipole is the simplest and most widely used wire antenna. It consists of two quarter-wavelength conductors placed end-to-end for a total length of approximately a half wavelength. This antenna is resonant and provides good performance when properly constructed.
The calculator uses the standard half-wave dipole formula:
Where:
Explanation: The formula calculates the physical length of a half-wave dipole antenna for a given frequency, accounting for the velocity factor of electromagnetic waves in a conductor.
Details: Proper dipole length is crucial for antenna resonance at the desired frequency. An accurately sized dipole will have a low standing wave ratio (SWR) and efficient radiation characteristics.
Tips: Enter the desired operating frequency in MHz. The calculator will provide the total length for a half-wave dipole in feet. For best results, the antenna should be slightly longer than calculated and then trimmed for optimal SWR.
Q1: Why 468 instead of 492?
A: The number 468 accounts for the velocity factor (about 95%) of electromagnetic waves in a conductor, while 492 would be the free-space half-wavelength.
Q2: How accurate is this calculation?
A: It provides a good starting point, but final length should be adjusted based on actual SWR measurements due to environmental factors.
Q3: Can I use this for VHF/UHF frequencies?
A: Yes, the formula works for all frequencies, though construction becomes more challenging at higher frequencies.
Q4: What about metric measurements?
A: For meters, use 143/f (MHz). The calculator provides results in feet which can be converted (1 foot = 0.3048 meters).
Q5: Does wire thickness affect the length?
A: Thicker conductors require slightly shorter lengths due to increased capacitance, but the difference is usually negligible for practical purposes.