Dual Field Pi Coils

[Aziz]

Hi Stefan,

Aziz, really cool visualizations!

thanks, it was a long way to achieve this. The coil software is written by me. I am adding as many functionality as I need. I am not giving the coil software away to ensure that coil improvements will be shared in the public domain.

Interesting that the triple coils appear to have a "cold" spot between the two outer coils. It's too bad there isn't a way to reflect a magnetic field so that less energy is expended on the upper side of the coils.

This "cold" spot does not matter. The coil housing won't allow targets to come too close the coil. The one sided exitation of magnetic fields isn't possible.

Have you tried simulating other shapes that are asymmetrical along the z-axis such as cones?

This wouldn't make much sense or get some benefit.

Aziz

[MagnetMan]

Aziz, really cool visualizations! Interesting that the triple coils appear to have a "cold" spot between the two outer coils. It's too bad there isn't a way to reflect a magnetic field so that less energy is expended on the upper side of the coils. Have you tried simulating other shapes that are asymmetrical along the z-axis such as cones?

I'm new to the forum, so I'm curious about the software you use, too!

-Stefan

[Tinkerer]

Thanks Aziz,
These are excellent visualizations.

Tinkerer

[Aziz]

finally

finally

[Aziz]

to be continued..

to be continued..

[Aziz]

to be continued...

to be continued...

[Aziz]

Magnetic Field Strength Cross-Section Pictures

Hello friends,

is anybody interested on the magnetic field strength (MF) pictures of the compared coil configurations?

I am sure, you will be.
Ok, eat this.

All pictures have the same 3D projection parameters. The x-axis is not shown (going from your eyes into your display). The y-axis shows the longest coil dimension. The z-axis the height/depth above/below coil. The small target is still placed at z=10 cm (can you see it?). The axis length is 40 cm (going from -40 cm .. +40 cm). It is divided every 2 cm for a better comparision. So you can orient at it.

16 MF pictures will follow now ...

Have fun,

Aziz

[Aziz]

Hi Ian,

Hi Aziz,
Here is a picture of my 28 x18/15 x 10 Duel-Field and I concur with Peter on the performance.
Regards,Ian.
http://i806.photobucket.com/albums/y...lFieldCoil.jpg

it's looking very very nice. It's a marvellous craftsmanship.
Aziz

[IBGold]

Hi Aziz,
Here is a picture of my 28 x18/15 x 10 Duel-Field and I concur with Peter on the performance.
Regards,Ian.
http://i806.photobucket.com/albums/y...lFieldCoil.jpg

[Aziz]

Hi detectormods,

Hi Aziz,

Back from Gold field tests.

Real tests in the field show that the noise does NOT INCREASE with a split winding. This is different to my bench testing on a bed of hot rocks, if anything the dual field coil was quieter than one with a diameter of the largest winding.

thanks for your valuable feedback and field tests. This is indeed a good news. One could make a 0.67R and 1R split coil for more hotter grounds. This should even be more quiet. Then quite big coils (18"+) could be used in the field with the benefit of sensitivity to small targets too. The high sensitivity in the near detection zone can not be fully used due to some distance of the coil to the ground.

Aziz

[detectormods]

Hi Aziz,

Back from Gold field tests.

Real tests in the field show that the noise does NOT INCREASE with a split winding. This is different to my bench testing on a bed of hot rocks, if anything the dual field coil was quieter than one with a diameter of the largest winding.

[Aziz]

Hi Rov,

Hi Aziz,in your graph softwares what do the graduations for X-Y (horizontal to vertical) mean too people that dont know an want to interpret simply?you do not have reference to scales for people to follow.Thanks!

x-axis: target distance in cm from the center position of the coil arrangement
y-axis: induced voltage from the secondary magnetic fields (target's eddy current caused magnetic field)

The absolute value of the induced voltage is not important. Only the relation to the other coils or configurations. As all the configurations are normalized to a particular specification, one can compare different coil configurations together. It's just tells, how an equivalent coil configuration compares to other equivalent configurations.

If I do not normalize, then it would be difficult to say, whether a configuration performs better or not.

All coil configurations are normalized to L=300µH (total coil inductivity) and 500 cm² coil flux area (coil coverage area). This means, all configurations will emit same magnetic field energy to the target.


Aziz

[Rov]

Hi Aziz,in your graph softwares what do the graduations for X-Y (horizontal to vertical) mean too people that dont know an want to interpret simply?you do not have reference to scales for people to follow.Thanks!

[Aziz]

Dual Field Coil Turn Variations

This is the Dual Field 0.5 coil, where the turn ratio of the inner to outer windings are varied (see below).

Syntax:
N=inner:outer windings turn ratio

N=1:3 means, the outer coil winding turns has 3 times more windings than the inner coil
N=3:1 means, the inner coil winding turns has 3 times more windings than the outer coil

All variations have the same inductance L and same coil flux area of 500 cm² (outer coil).

Aziz

[Aziz]

Further Dual Field Coil Analysis

Hi all,

I want to show you, how the Dual Field coil behaves to different size targets. And how the Dual Field coil compares to other coil types (see below).
T=10: 10 mm target diameter
T=20: 20 mm target diameter
T=40: 40 mm target diameter

Aziz