What is the length in feet of a 1-wavelength antenna at 7.5 MHz according to the formula 1 wavelength (feet) = 936 / Frequency (MHz)?

What is the length in feet of a 1-wavelength antenna at 7.5 MHz according to the formula 1 wavelength (feet) = 936 / Frequency (MHz)?

• A. 124.8 ft
• B. 936 ft
• C. 70.0 ft
• D. 236.4 ft

Answer: (A)

Wavelength is the physical length of one cycle of the radio wave, and an antenna that is one wavelength long has a length equal to that wavelength. The given rule provides a convenient way to convert frequency directly to feet: 1 wavelength (feet) = 936 divided by Frequency (MHz). This constant incorporates the speed of light and unit conversions, and it shows that as frequency goes up, the wavelength—and thus a 1-wavelength antenna length—gets shorter. At 7.5 MHz, you simply compute 936 ÷ 7.5, which equals 124.8 feet. So a 1-wavelength antenna at 7.5 MHz is about 124.8 feet long. The other numbers don’t fit this calculation because they would correspond to different frequencies or use a different constant.

Wavelength is the physical length of one cycle of the radio wave, and an antenna that is one wavelength long has a length equal to that wavelength. The given rule provides a convenient way to convert frequency directly to feet: 1 wavelength (feet) = 936 divided by Frequency (MHz). This constant incorporates the speed of light and unit conversions, and it shows that as frequency goes up, the wavelength—and thus a 1-wavelength antenna length—gets shorter.

At 7.5 MHz, you simply compute 936 ÷ 7.5, which equals 124.8 feet. So a 1-wavelength antenna at 7.5 MHz is about 124.8 feet long. The other numbers don’t fit this calculation because they would correspond to different frequencies or use a different constant.