A 1-wavelength antenna is 100 ft long. What is the operating frequency in MHz?

A 1-wavelength antenna is 100 ft long. What is the operating frequency in MHz?

• A. 9.36 MHz
• B. 93.6 MHz
• C. 49.2 MHz
• D. 18.7 MHz

Answer: (A)

The frequency is set by the wavelength because a 1-wavelength antenna length equals the signal’s wavelength. Use f = c / λ, where c is the speed of light. Convert the length to meters: 100 ft × 0.3048 m/ft = 30.48 m. With c ≈ 3.00 × 10^8 m/s, f ≈ (3.00 × 10^8) / 30.48 ≈ 9.84 × 10^6 Hz, or about 9.84 MHz. In practice, constants are often rounded, so the frequency comes out around 9.8 MHz. Among the given options, 9.36 MHz is the closest match to that value. Therefore the operating frequency is about 9.8 MHz (the listed option reflects the closest approximation).

The frequency is set by the wavelength because a 1-wavelength antenna length equals the signal’s wavelength. Use f = c / λ, where c is the speed of light.

Convert the length to meters: 100 ft × 0.3048 m/ft = 30.48 m. With c ≈ 3.00 × 10^8 m/s, f ≈ (3.00 × 10^8) / 30.48 ≈ 9.84 × 10^6 Hz, or about 9.84 MHz.

In practice, constants are often rounded, so the frequency comes out around 9.8 MHz. Among the given options, 9.36 MHz is the closest match to that value. Therefore the operating frequency is about 9.8 MHz (the listed option reflects the closest approximation).