High frequency - Wikipedia
Medium frequency - Wikipedia
What's The Difference Between HF, VHF and UHF?
The Range of Ham Radio: A Guide to How Far You Can Talk
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High Frequency (HF) Radio
HF Surface Wave Propagation (Ground Wave) | VU2NSB.com - Amazing Amateur Radio
Radio Distance Range Comparison of Ham CB FRS MURS GMRS Radios.
Military and Amateur HF Radios – the Basics - Zhongyuan Zhao, Ph.D
Why You (Still) Might Need a High Frequency Radio Aboard, Part 2 | BoatTEST
SWS - Other Topics - Introduction to HF Radio Propagation
HF Radiation - Choosing the right frequency
Radio Distance Range Comparison of Ham CB FRS MURS GMRS Radios.
Why is the HF radio set communication range higher than the VHF radio set? - Quora
How Far Can I Communicate? | NewHams.info
The Ionosphere
HF radio becomes low-cost alternative to satellite | High-frequency radio - Urgent Communications article
Which Frequency Band is Best For You? - MRA Two Way Radio California
Refraction of an HF Radio Wave in the Ionosphere
What are Radio Frequency bands and its uses? - RF Page
HF | frequency band | Britannica
Marine HF Frerquencies
The Range of Ham Radio: A Guide to How Far You Can Talk
