A technician uses a 1-wavelength antenna tuned to 10 MHz. What is the approximate length in feet?

A technician uses a 1-wavelength antenna tuned to 10 MHz. What is the approximate length in feet?

• A. 93.6 ft
• B. 46.8 ft
• C. 187.2 ft
• D. 62.4 ft

Answer: (A)

The length of a 1-wavelength antenna equals the free-space wavelength of the signal. Wavelength is found from λ = c / f. Using c ≈ 3.0 × 10^8 m/s and f = 10 MHz (1.0 × 10^7 Hz), λ ≈ 30 meters, which is about 98 feet. Among the given options, 93.6 feet is the closest approximate full-wavelength length at 10 MHz. In practical field references this rounded value is commonly used, so it best represents a full-wavelength radiator at that frequency. The other choices correspond to lengths that are noticeably shorter or longer than a full wavelength at 10 MHz (e.g., lengths near a quarter-wavelength or two wavelengths), which aren’t correct for a 1-wavelength antenna.

The length of a 1-wavelength antenna equals the free-space wavelength of the signal. Wavelength is found from λ = c / f. Using c ≈ 3.0 × 10^8 m/s and f = 10 MHz (1.0 × 10^7 Hz), λ ≈ 30 meters, which is about 98 feet.

Among the given options, 93.6 feet is the closest approximate full-wavelength length at 10 MHz. In practical field references this rounded value is commonly used, so it best represents a full-wavelength radiator at that frequency. The other choices correspond to lengths that are noticeably shorter or longer than a full wavelength at 10 MHz (e.g., lengths near a quarter-wavelength or two wavelengths), which aren’t correct for a 1-wavelength antenna.