Ferrite Rod Antenna: Understanding How It Works

[bocchesegiacomo]

I can't understand how a ferrite rod antenna works. Someone can explain it to me?

 

[berkeman]

I can't understand how a ferrite rod antenna works. Someone can explain it to me?

Welcome to the PF.

What reading have you done so far? Can you post links to that reading, and ask specific questions about the parts you are not getting? What is your background so far in math and physics and EE?

 

[bocchesegiacomo]

Antennas are somthing studied also in physics. I am new in this forum and i don t know what answers i can post and what not

 

[bocchesegiacomo]

What is EE?

 

[berkeman]

What is EE?

Electrical Engineering, or at least what is your background in electronics so far? If you are just starting out, that is fine. It's good to be curious and want to learn.

Here is a tutorial about ferrite rod antennas that I found quickly with Google -- it looks pretty good.

http://www.radio-electronics.com/info/antennas/ferrite_rod_antenna/ferrite_rod_antenna.php

Ferrite rod antennas are used to make short receiving antennas when a normal (half wavelength size) antenna would just be too big. Like for AM radio stations, which are generally using a frequency band around 1MHz, so 1 wavelength is 300 meters. A 150 meter antenna would be kind of hard to fit in your car...

 

[litup]

Electrical Engineering, or at least what is your background in electronics so far? If you are just starting out, that is fine. It's good to be curious and want to learn.

Here is a tutorial about ferrite rod antennas that I found quickly with Google -- it looks pretty good.

http://www.radio-electronics.com/info/antennas/ferrite_rod_antenna/ferrite_rod_antenna.php

Ferrite rod antennas are used to make short receiving antennas when a normal (half wavelength size) antenna would just be too big. Like for AM radio stations, which are generally using a frequency band around 1MHz, so 1 wavelength is 300 meters. A 150 meter antenna would be kind of hard to fit in your car...

Nah, you could use a mere 75 meters also...Seriously, I have thought about the problem for hams using mobile antennae, where you have say a 6 foot whip and special matching networks to get say a 20 meter signal to go through a 2 meter long antenna. I thought about the idea of using a small airfoil attached to a long wire attached to the top of the whip and say you have a 3 meter long wire at right angles to the whip and held in space by the air going by the moving car. That would seem to me to reduce the tuning problem. Of course you better stop talking when the car stops:)

 

[bocchesegiacomo]

Electrical Engineering, or at least what is your background in electronics so far? If you are just starting out, that is fine. It's good to be curious and want to learn.

Here is a tutorial about ferrite rod antennas that I found quickly with Google -- it looks pretty good.

http://www.radio-electronics.com/info/antennas/ferrite_rod_antenna/ferrite_rod_antenna.php

Ferrite rod antennas are used to make short receiving antennas when a normal (half wavelength size) antenna would just be too big. Like for AM radio stations, which are generally using a frequency band around 1MHz, so 1 wavelength is 300 meters. A 150 meter antenna would be kind of hard to fit in your car... [emoji2]

I know electronics quite well but i don t know much about magnetic fields, electromagnetic waves and antennas

 

[bocchesegiacomo]

Electrical Engineering, or at least what is your background in electronics so far? If you are just starting out, that is fine. It's good to be curious and want to learn.

Here is a tutorial about ferrite rod antennas that I found quickly with Google -- it looks pretty good.

http://www.radio-electronics.com/info/antennas/ferrite_rod_antenna/ferrite_rod_antenna.php

Ferrite rod antennas are used to make short receiving antennas when a normal (half wavelength size) antenna would just be too big. Like for AM radio stations, which are generally using a frequency band around 1MHz, so 1 wavelength is 300 meters. A 150 meter antenna would be kind of hard to fit in your car... [emoji2]

Thank you

 

[bocchesegiacomo]

Electrical Engineering, or at least what is your background in electronics so far? If you are just starting out, that is fine. It's good to be curious and want to learn.

Here is a tutorial about ferrite rod antennas that I found quickly with Google -- it looks pretty good.

http://www.radio-electronics.com/info/antennas/ferrite_rod_antenna/ferrite_rod_antenna.php

Ferrite rod antennas are used to make short receiving antennas when a normal (half wavelength size) antenna would just be too big. Like for AM radio stations, which are generally using a frequency band around 1MHz, so 1 wavelength is 300 meters. A 150 meter antenna would be kind of hard to fit in your car... [emoji2]

I am also able to use differential equations for electronics

 

[berkeman]

Have you read through the link I provided yet?

 

[bocchesegiacomo]

Yes i red it a moment ago and i understood

 

[bocchesegiacomo]

I asked you that question because I am interested in wireless transmission of Energy and maybe ferrite rod antennas can be Used for wireless transmission of Energy I have understood that that kind of antennas arent very efficient.

 

[berkeman]

I asked you that question because I am interested in wireless transmission of Energy and maybe ferrite rod antennas can be Used for wireless transmission of Energy I have understood that that kind of antennas arent very efficient.

Ferrite rod antennas are commonly use for receive antennas because they are compact. They are not generally used for transmission, because they are not very efficient transmitters of that long-wavelength RF.

As I said in your new thread about wireless energy transmission, don't believe the things that you read that claim high efficiency transmission over distances. That is generally not true.

 

[bocchesegiacomo]

Ok thank you.but i did an experiment on wireless transmission with resonant coupling and i have seen that the inverse square distance law does not work

 

[berkeman]

Ok thank you.but i did an experiment on wireless transmission with resonant coupling and i have seen that the inverse square distance law does not work

Not in the near field, but it does in the far field.

If you have a link to a mainstream paper about wireless energy transmission, you can link to it here and ask specific questions. Do not post any YouTube videos or links to papers by Nikola Tesla, etc. please.

 

[bocchesegiacomo]

Not in the near field, but it does in the far field.

If you have a link to a mainstream paper about wireless energy transmission, you can link to it here and ask specific questions. Do not post any YouTube videos or links to papers by Nikola Tesla, etc. please.

Here there is a photo about the concentration of the field on the resonant coil by wikipedia

 

[berkeman]

Here there is a photo about the concentration of the field on the resonant coil by wikipediaView attachment 218552

That is no help at all.

Go to the References section of the Wikipedia article you are reading, and find the mainstream source for the information you want to discuss please.

 

[bocchesegiacomo]

That is no help at all.

Go to the References section of the Wikipedia article you are reading, and find the mainstream source for the information you want to discuss please.

Here is the right image

 

[berkeman]

Here is the right imageView attachment 218553

And notice how the two coils are lined up closely, so there is a lot of coupling between them. That is how some electric toothbrushes are charged when placed in their holders next to the sink. That is not far-field energy transmission.

I hope that makes sense now.

 

[bocchesegiacomo]

Ok now i understood. I am italian so i don't know some words well.

 

[berkeman]

No worries. I'm 100% sure that your English is much better than my Italian!