How does the size of an object affect RF propagation?

AI Thread Summary
The size of an object significantly impacts RF propagation, with refraction occurring only in objects larger than the wavelength. Objects smaller than the wavelength primarily scatter RF signals, while regular arrays of small objects can cause diffraction. Additionally, diffraction happens at the edges of larger objects. Understanding these phenomena can be enhanced by studying other types of waves, such as microwaves and visible light. Overall, the relationship between object size and RF transmission is crucial for effective communication and signal clarity.
barry.haworth
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Hi there, can anyone please advise how the size of an obstructing object affects the propagation of an RF transmission? Eg, for instance does refraction only occur in objects that are larger than the wavelength or does it occur in objects smaller than the wavelength? I can find heaps of info about RF propagation but very little on how the various phenomena such as absorption, reflection, refraction, diffraction, scattering etc is affected by the size of an object relative to the wavelength? I would appreciate any and all feedback. Many thanks
 
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Refraction will only occur on objects larger than the wavelength.
Isolated objects smaller than the wavelength will scatter.
A regular array of small objects with spacing similar to the wavelength will diffract.
Diffraction will also occur at the edges of large objects.

These are general wave phenomena, not limited to RF. You might get a better understanding if you also look at other kinds of waves, such as microwaves, visible light, and x-rays. Just don't study water waves too much, they are highly non-linear.
 
barry.haworth said:
Hi there, can anyone please advise how the size of an obstructing object affects the propagation of an RF transmission? Eg, for instance does refraction only occur in objects that are larger than the wavelength or does it occur in objects smaller than the wavelength? I can find heaps of info about RF propagation but very little on how the various phenomena such as absorption, reflection, refraction, diffraction, scattering etc is affected by the size of an object relative to the wavelength? I would appreciate any and all feedback. Many thanks
I just happen to be in the process of writing a book for the ARRL dedicated specifically to radio propagation, especially ionospheric.

But, you've had some good answers here, as ionospheric refraction is a very MACRO phenomenon. The ionosphere, as a whole has a very large "radar cross-section" but can also be extremely lossy...or not.

Stay tuned!

Eric
 
Dear M Quack, thank you for your prompt reply, it was very useful. I appreciate your help!

Many thanks,

Barry
 
Hi Eric, good luck with the book! Would love a copy when you get it published.
Many thanks,
Barry
 
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