Antenna size is related to frequency; which statement is correct?

• A. Antenna size is independent of frequency.
• B. Antenna size grows with frequency.
• C. High Frequency: Small Size; Low Frequency: Large Size.
• D. Antenna size decreases with lower frequency.

Answer: (C)

Frequency and antenna size are tied to wavelength. The wavelength of a signal is roughly the speed of light divided by frequency, so as frequency goes up, wavelength gets shorter. Many antennas are designed to be a fraction of that wavelength, such as a quarter or half of it. That means higher frequencies allow smaller antennas, while lower frequencies require larger antennas to resonate effectively. In radar, this is why high-frequency systems use compact antennas and lower-frequency systems need bigger ones to maintain performance.

Among the choices, the one that aligns with this relationship is that high frequency corresponds to small size and low frequency to large size. The other statements conflict with the basic link between frequency and wavelength and how antenna dimensions scale with wavelength.