How does the size of an object affect RF propagation?

In summary, the size of an obstructing object affects the propagation of an RF transmission. Refraction only occurs on objects larger than the wavelength, and diffraction and scattering occur at the edges of large objects.
  • #1
barry.haworth
5
0
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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  • #2
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.
 
  • #3
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
 
  • #4
Dear M Quack, thank you for your prompt reply, it was very useful. I appreciate your help!

Many thanks,

Barry
 
  • #5
Hi Eric, good luck with the book! Would love a copy when you get it published.
Many thanks,
Barry
 

Related to How does the size of an object affect RF propagation?

What is RF propagation?

RF propagation refers to the movement or transmission of radio frequency (RF) waves through a medium, such as air or water. These waves carry information and are used in various forms of communication, such as radio, television, and cell phones.

What factors affect RF propagation?

Several factors can impact RF propagation, including the frequency of the wave, the distance between the transmitter and receiver, the type of terrain, and any obstacles that may be present, such as buildings or vegetation. Weather conditions, such as rain or fog, can also affect RF propagation.

What are the different types of RF propagation?

The two main types of RF propagation are line-of-sight (LOS) and non-line-of-sight (NLOS). In LOS propagation, the RF waves travel directly from the transmitter to the receiver without any obstructions. In NLOS propagation, the waves may reflect, diffract, or scatter off of objects or terrain before reaching the receiver.

How does RF propagation impact wireless communication?

Understanding RF propagation is crucial for designing and optimizing wireless communication systems. The strength and quality of the RF signal can be affected by various factors, and it is important to consider these in order to ensure reliable and efficient communication.

What are some common challenges in RF propagation?

Some common challenges in RF propagation include interference from other sources, signal loss due to distance or obstructions, and multipath propagation, which occurs when the RF waves take multiple paths to the receiver, resulting in signal distortion. These challenges can be mitigated through proper antenna placement, signal amplification, and other techniques.

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