Increase Electromagnetics emmission?

[Toothless]

First of all - I'm new here, and this forum looks awesome!

As for my post, I'm going to be using an inductor to emit an electromagnetic field, and was wondering if you could somehow either increase it or isolate the emission maybe via antenna? I know antennas are typically used to convert currents to waves, but could it suffice for this case?

Also, is an inductor the best way to emit an electromagnetic field?

Thanks!
~Toothless

PS: If this is in the wrong forum/sub-forum, sorry!

 

[berkeman]

First of all - I'm new here, and this forum looks awesome!

As for my post, I'm going to be using an inductor to emit an electromagnetic field, and was wondering if you could somehow either increase it or isolate the emission maybe via antenna? I know antennas are typically used to convert currents to waves, but could it suffice for this case?

Also, is an inductor the best way to emit an electromagnetic field?

Thanks!
~Toothless

PS: If this is in the wrong forum/sub-forum, sorry!

Welcome to the PF.

Can you say more about your application? Are you wanting to make a small localized oscillating magnetic field? Perhaps in a transformer gap or similar?

Or are you wanting to launch an EM wave to be received at some other station a distance away? What frequencies are you wanting to use? How far do you want to communicate?

Keep in mind that the RF spectrum is regulated by the governments of most countries, and you can't just go transmitting on any old frequency that you want. Licenses are required for most radio transmissions...

 

[Toothless]

Welcome to the PF.

Can you say more about your application? Are you wanting to make a small localized oscillating magnetic field? Perhaps in a transformer gap or similar?

Or are you wanting to launch an EM wave to be received at some other station a distance away? What frequencies are you wanting to use? How far do you want to communicate?

Keep in mind that the RF spectrum is regulated by the governments of most countries, and you can't just go transmitting on any old frequency that you want. Licenses are required for most radio transmissions...

Oh sorry for leaving out some details. I'm basically wanting to make a small localized oscillating magnetic field as you said, for experimenting purposes. I'm curious as to how far I could extend its range. Also thanks for the welcoming.

 

[berkeman]

Oh sorry for leaving out some details. I'm basically wanting to make a small localized oscillating magnetic field as you said, for experimenting purposes. I'm curious as to how far I could extend its range. Also thanks for the welcoming.

What frequencies will you want to be using?

For small volumes, say about the size of a tennis ball, you can use a "C" shaped piece of metal (laminated iron for low frequencies, or ferrite for higher frequencies), where the tennis ball would fit in the gap of the C. You would wind your exciting coils around the long part of the C, to generate an oscillating B-field in the gap.

For larger areas (where it is not practical to have such a large C-shaped piece of metal), you can use a coil called a Helmholtz Coil:

http://en.wikipedia.org/wiki/Helmholtz_coil

to generate a fairly uniform B-field in the volume between the two coils.

 

[Toothless]

What frequencies will you want to be using?

For small volumes, say about the size of a tennis ball, you can use a "C" shaped piece of metal (laminated iron for low frequencies, or ferrite for higher frequencies), where the tennis ball would fit in the gap of the C. You would wind your exciting coils around the long part of the C, to generate an oscillating B-field in the gap.

For larger areas (where it is not practical to have such a large C-shaped piece of metal), you can use a coil called a Helmholtz Coil:

http://en.wikipedia.org/wiki/Helmholtz_coil

to generate a fairly uniform B-field in the volume between the two coils.

Okay, thanks! Now what if I want to try and isolate the field instead of oscillation. Would I just use a simple Former using Copper Wire and a ferrite core?

 

[berkeman]

Okay, thanks! Now what if I want to try and isolate the field instead of oscillation. Would I just use a simple Former using Copper Wire and a ferrite core?

Could you please re-state your question with more details? It's not translating very well.

 

[Toothless]

With both methods you stated, a magnetic field will only oscillate in a limited area. Now what if I wanted to extend it outward toward an isolated direction.. perhaps just generally forward?

 

[berkeman]

With both methods you stated, a magnetic field will only oscillate in a limited area. Now what if I wanted to extend it outward toward an isolated direction.. perhaps just generally forward?

Unless you launch an EM wave, the magnetic field will be confined to the volume between the ends of the inductor. If you use a rod inductor instead of a C-shaped inductor, the field will spread out, but will be quite weak at a distance.

 

[Toothless]

How could I launch an EM wave?

 

[berkeman]

How could I launch an EM wave?

First you get a license for the band you want to transmit in. Then you build and test the hardware of your transceiver.

 

[sophiecentaur]

How could I launch an EM wave?

The point has already been made that you need to specify what frequency you plan to operate with. This is important because you you need to be using a 'legal' frequency and an appropriate radiating element.
If you don't have any idea about this and you want to make an operating system then you should start with a self assembly kit with circuit and instructions. (That is a quicker method of getting a result than learning it all from square one!)

Also, if you want to 'launch' a wave then you also need to be able to receive / detect it - or you won't know if the kit is working.