Radio waves received at distance <1 wavelength

In summary, when a radio station sends out AM waves with a wavelength of >50m and you are standing with a receiver at a distance of <25m, the signal will be stronger closer in and weaker the further out you go. The strength will also depend on the receiver's antenna and its coupling to the transmitter's antenna. In the near field, induced currents can be very high and can potentially destroy the receiver even if it is more than 1 wavelength away from the transmitter.
  • #1
jimmylegss
62
0
So let's say a radio station sends out AM waves with a wavelenght of like >50m. You are standing with a receiver at a distance of <25m, what happens to the signal? Is it different or the same as if you were standing a longer distance away then 1 wavelenght?

Thanks
 
Engineering news on Phys.org
  • #2
jimmylegss said:
Is it different or the same as if you were standing a longer distance away then 1 wavelenght?

without getting into the complexities of near field/far field theory

the signal will just be stronger closer in and weaker the further out you go

Dave
 
  • #3
It will depend on your receiver's antenna.
If the RX antenna couples to the TX antenna it might deliver sufficient energy to destroy the RX.
It could also distort the radiation pattern of the TX antenna.
 
  • #4
But it has nothing to do with the fact that rx is closer then 1 wavelength from tx? So you could tune up tx enough to destroy rx even if they are more then 1 wavelength away from each other?
 
  • #5
jimmylegss said:
So you could tune up tx enough to destroy rx even if they are more then 1 wavelength away from each other?
You could tune a RX element with high Q to destroy the RX at some distance from the TX element. But it takes little coupling and no tuning to destroy the RX if you are in the very near field since induced currents in close proximity can be very high.
 

Related to Radio waves received at distance <1 wavelength

1. What are radio waves?

Radio waves are a type of electromagnetic radiation, also known as radio frequency energy. They are a form of energy that travels through space and can be used for communication and broadcasting.

2. How are radio waves produced?

Radio waves are produced when an alternating current flows through a conductor, such as an antenna. The changing current creates an electromagnetic field, which then radiates outwards as radio waves.

3. How far can radio waves travel?

Radio waves can travel long distances, depending on their frequency and the conditions of the atmosphere. Generally, lower frequency radio waves can travel farther than higher frequency waves.

4. What is the significance of receiving radio waves at a distance less than 1 wavelength?

Receiving radio waves at a distance less than 1 wavelength is significant because it indicates a phenomenon called "near-field" propagation. This means that the radio waves are still in close proximity to the source and have not yet fully radiated out into the far-field.

5. How are radio waves used in modern technology?

Radio waves are used in a variety of modern technologies, including radio and television broadcasting, cell phones, Wi-Fi, and satellite communication. They are also used in medical imaging, such as MRI machines, and in radar systems for navigation and weather forecasting.

Similar threads

Replies
14
Views
2K
  • Electrical Engineering
2
Replies
40
Views
1K
  • Electrical Engineering
Replies
14
Views
4K
Replies
2
Views
1K
  • Electrical Engineering
Replies
12
Views
935
Replies
68
Views
3K
  • Electrical Engineering
2
Replies
45
Views
4K
  • Electrical Engineering
Replies
17
Views
4K
  • Electrical Engineering
Replies
33
Views
4K
  • Electrical Engineering
Replies
9
Views
5K
Back
Top