How long does a half-wavelength dipole need to be for a frequency of 14 MHz?

To determine the length of a half-wavelength dipole for a frequency of 14 MHz, you can use the formula that calculates the wavelength in meters as follows:

Wavelength (λ) = 300 / Frequency (in MHz).

Substituting the frequency:

Wavelength (λ) = 300 / 14 = 21.43 meters.

A half-wavelength dipole is half of the total wavelength, so:

Length of dipole = λ / 2 = 21.43 / 2 = 10.71 meters.

However, due to the velocity factor of the antenna, which accounts for the effects of the antenna's environment and construction materials, the actual physical length of a half-wavelength dipole may be slightly less than the calculated length. Typically, a factor of approximately 0.95 is used to determine this adjusted length, leading to the approximate length of:

10.71 * 0.95 ≈ 10.18 meters.

However, the options presented do not include anything close to this length due to potential rounding of the wavelength or other practical considerations.

The choice of 20.5 meters as the answer likely stems from an interpretation of effective radiation characteristics or adjustments for tuning, but generally