What formula is used to calculate the length of a 1/4 wavelength whip antenna for a frequency in MHz?

What formula is used to calculate the length of a 1/4 wavelength whip antenna for a frequency in MHz?

• A. 234 / Frequency in MHz.
• B. 300 / Frequency in MHz.
• C. 186000 / Frequency in Hz.
• D. 2.34 / Frequency in MHz.

Answer: (A)

A quarter-wavelength whip is designed so its physical length matches one quarter of the signal’s wavelength. To use frequency in MHz and get a practical length in feet, you convert the wavelength in feet and then take a quarter of it. Wavelength in feet is about 983.6 divided by f(MHz), so a quarter of that is roughly 246 divided by f(MHz). In many practical references this is rounded to 234/f(MHz) to account for real‑world effects like end loading and mounting, giving a convenient rule of thumb: length in feet ≈ 234 divided by the frequency in MHz. So the best choice is the one that uses 234 divided by the frequency in MHz because it directly implements the quarter-wavelength relationship in practical units. The other options misapply units or use constants that don’t align with how antenna length scales with frequency.

A quarter-wavelength whip is designed so its physical length matches one quarter of the signal’s wavelength. To use frequency in MHz and get a practical length in feet, you convert the wavelength in feet and then take a quarter of it. Wavelength in feet is about 983.6 divided by f(MHz), so a quarter of that is roughly 246 divided by f(MHz). In many practical references this is rounded to 234/f(MHz) to account for real‑world effects like end loading and mounting, giving a convenient rule of thumb: length in feet ≈ 234 divided by the frequency in MHz.

So the best choice is the one that uses 234 divided by the frequency in MHz because it directly implements the quarter-wavelength relationship in practical units. The other options misapply units or use constants that don’t align with how antenna length scales with frequency.