Frequency for short distance terrestrial communication?

Frequency for short distance terrestrial communication?

• A. 3-30 GHz
• B. 30-300 MHz
• C. 300-1000 MHz
• D. 3-30 MHz

Answer: (B)

Short distance terrestrial communication uses frequencies in the VHF range because these wavelengths travel mainly by line‑of‑sight and allow practical antenna sizes for ground, vehicle, and portable radios. The 30–300 MHz band provides a reliable balance between coverage and hardware practicality for local, ground-based voice and data links. Lower frequencies (3–30 MHz) rely on ionospheric reflection for long reach, which makes local, predictable communication less reliable. Higher frequencies (300–1000 MHz and above) are also line-of-sight but demand more precise antennas and often more infrastructure for short-range links; they’re not as commonly associated with everyday short-distance terrestrial voice in typical training contexts.

Short distance terrestrial communication uses frequencies in the VHF range because these wavelengths travel mainly by line‑of‑sight and allow practical antenna sizes for ground, vehicle, and portable radios. The 30–300 MHz band provides a reliable balance between coverage and hardware practicality for local, ground-based voice and data links.

Lower frequencies (3–30 MHz) rely on ionospheric reflection for long reach, which makes local, predictable communication less reliable. Higher frequencies (300–1000 MHz and above) are also line-of-sight but demand more precise antennas and often more infrastructure for short-range links; they’re not as commonly associated with everyday short-distance terrestrial voice in typical training contexts.