What frequency range is referred to as HF?
The correct answer is C: 3 to 30 MHz. HF (High Frequency) refers to the frequency range from 3 MHz to 30 MHz. This includes popular amateur bands like 80 meters (3.5-4.0 MHz), 40 meters (7.0-7.3 MHz), 20 meters (14.0-14.35 MHz), 15 meters (21.0-21.45 MHz), and 10 meters (28.0-29.7 MHz).
HF frequencies are capable of long-distance communications through ionospheric propagation. The ionosphere can refract HF signals, allowing them to travel thousands of miles. HF is where most long-distance (DX) amateur radio communications occur. Technician licensees have limited HF privileges (primarily on 10 meters), while General and Extra class operators have full HF privileges.
Exam Tip
HF = 3-30 MHz. Remember: HF (High Frequency) is 3 MHz to 30 MHz. This includes 80m, 40m, 20m, 15m, and 10m bands where long-distance communications are possible.
Memory Aid
"**H**F = **3**-**3**0 **M**Hz (think 'HF = 3-30 MHz')"
Real-World Application
You're operating on 28.4 MHz, which is in the 10-meter band. This frequency is within the HF range (3-30 MHz). Your 10-meter signal can be refracted by the ionosphere, allowing contacts over thousands of miles, which is characteristic of HF propagation.
FCC Part 97.303Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. 300-3000 MHz is UHF, not HF. HF is much lower.
Option B: Incorrect. 30-300 MHz is VHF, not HF. HF is 3-30 MHz.
Option D: Incorrect. 300-3000 kHz is 0.3-3 MHz, which is mostly below the HF range. HF is 3-30 MHz.
题目解析
The correct answer is C: 3 to 30 MHz. HF (High Frequency) refers to the frequency range from 3 MHz to 30 MHz. This includes popular amateur bands like 80 meters (3.5-4.0 MHz), 40 meters (7.0-7.3 MHz), 20 meters (14.0-14.35 MHz), 15 meters (21.0-21.45 MHz), and 10 meters (28.0-29.7 MHz). HF frequencies are capable of long-distance communications through ionospheric propagation. The ionosphere can refract HF signals, allowing them to travel thousands of miles. HF is where most long-distance (DX) amateur radio communications occur. Technician licensees have limited HF privileges (primarily on 10 meters), while General and Extra class operators have full HF privileges.
考试技巧
HF = 3-30 MHz. Remember: HF (High Frequency) is 3 MHz to 30 MHz. This includes 80m, 40m, 20m, 15m, and 10m bands where long-distance communications are possible.
记忆口诀
**H**F = **3**-**3**0 **M**Hz (think 'HF = 3-30 MHz')
实际应用示例
You're operating on 28.4 MHz, which is in the 10-meter band. This frequency is within the HF range (3-30 MHz). Your 10-meter signal can be refracted by the ionosphere, allowing contacts over thousands of miles, which is characteristic of HF propagation.
错误选项分析
Option A: Incorrect. 300-3000 MHz is UHF, not HF. HF is much lower. Option B: Incorrect. 30-300 MHz is VHF, not HF. HF is 3-30 MHz. Option D: Incorrect. 300-3000 kHz is 0.3-3 MHz, which is mostly below the HF range. HF is 3-30 MHz.
知识点
HF, Frequency range, 3-30 MHz, Ionospheric propagation
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.