Here’s your video introduction to Lesson 7.1, The Ionosphere, from the ARRL General Class License Manual for Ham Radio. When you have finished, click here to return to the list of videos. If you have any questions on this topic, please use the comment form.

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### 2 Responses to Ham Radio General Class License Lesson 7.1, The Ionosphere

1. Dave says:

Lee, thanks for the kind words! Indeed, they do represent lots of work. Regarding ionospheric refraction, I’ve wondered about that too. There are some diagrams at http://www.tpub.com/neets/book10/40e.htm. One possibility is that the “inverted” refraction is because the radio waves encounter a lower index of refraction upon entering the ionosphere. In other words, the index of refraction in the atmosphere is greater than that found in the ionosphere, which actually lives well above most of the sensible atmosphere.

2. Lee says:

Hi Dave,

First off, I would like to thank you for putting together these videos. As a teacher I can appreciate the difficulty of actually making hard subjects palatable and I think that you succeed in this regard with your instructional videos. Kudos to you sir!

My question is concerned with refraction. I am having trouble understanding the relationship with the frequency of an electromagnetic wave and the degree to which it is bent. From my understanding the higher frequencies are bent the most with visible light and prisms while in RF (still an electromagnetic wave), the higher frequencies are bent less. As you showed in your example, it looked like the red color was bent the least (and has the largest wavelength, highest frequency) while violet was bent the most (lowest wavelength, highest frequency, highest energy). What am I missing?

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