FM has a disadvantage described as wider bandwidth requiring more RF spectrum. Which option states this disadvantage?

FM has a disadvantage described as wider bandwidth requiring more RF spectrum. Which option states this disadvantage?

• A. Requires more power
• B. Travels less distance than AM
• C. Wider bandwidth uses more RF Spectrum
• D. Less affected by EMI

Answer: (C)

Wider bandwidth is built into how FM carries information. In frequency modulation, the carrier frequency is varied to encode the signal, which creates sidebands around the carrier. The more the carrier deviates (larger Δf) and the higher the modulating frequency (fm), the more sidebands appear, expanding the occupied spectrum. In practice, the approximate FM bandwidth is 2(Δf + fm); increasing deviation or modulating frequency pushes more energy into a larger portion of the spectrum. So the primary drawback is that FM uses more RF spectrum than AM for the same content, affecting channel availability and regulatory allocations. Other aspects like power, range, or EMI tolerance aren’t the fundamental spectrum-related disadvantage described here.

Wider bandwidth is built into how FM carries information. In frequency modulation, the carrier frequency is varied to encode the signal, which creates sidebands around the carrier. The more the carrier deviates (larger Δf) and the higher the modulating frequency (fm), the more sidebands appear, expanding the occupied spectrum. In practice, the approximate FM bandwidth is 2(Δf + fm); increasing deviation or modulating frequency pushes more energy into a larger portion of the spectrum. So the primary drawback is that FM uses more RF spectrum than AM for the same content, affecting channel availability and regulatory allocations. Other aspects like power, range, or EMI tolerance aren’t the fundamental spectrum-related disadvantage described here.