New Concentric Co-planar Coil with Strong MF.

[Aziz]

For all, who wants to experiment on different coil configuration, look at the table below. Keep the mean diameter of the coils as specified and take the number of windings for TX and Bucking coil as needed. Tolerance: +- 1-2 turns.
Aziz

[Aziz]

Wow! The coil even can be driven with high power LC-oscillator.
But I didn't tried the RX-part yet. Too much magnetic fields.
I have to limit the LC-oscillator power and protect the signal lines.

[gwzd]

Yes, today we had nice sunshine....
Aziz

Lucky you!
Regards
RA

[Aziz]

Hello,

I found great fundamental background on IB-coils now. Some simulations showed me, that this coil type isn't good as expected! So do not waste your time! Wait until I have some more good news!

The reason I found was the magnetic field strength decrease over the height z of the coil configuration. This decreases much more than compared to a standard IB-coil. It has obviously more magnetic strength on its nearby, but we want a magnetic field strength at a far distance to coil to achieve more depth sensitivity.

I will investigate more on the coming days/weeks, to design a better IB-coil. I have to implement some features on my coil software, to get more compareable coil configuration figures.
Aziz

[Sean_Goddard]

I agree with you Aziz, The Goverment CAN go to the devil!!

I hope your problems are sorted out soon. My German is very basic (sadly) but I think I understand what you are going through. Good luck, with that problem AND the coil design.

I'm sure you will sort things out.

[Aziz]

I agree with you Aziz, The Goverment CAN go to the devil!!

I hope your problems are sorted out soon. My German is very basic (sadly) but I think I understand what you are going through. Good luck, with that problem AND the coil design.

I'm sure you will sort things out.

Hi Sean,

The coil problems are the least one.

But with the German government with its perversity of justice, this seams to be an unsolveable problem. In Germany not really human rights are existing. This exists only for aryan people but not for me. Anyway, this is the main reason, why I am not willing to work for this damn government anymore. You all are profitting from this fact: I have 100% time for my hobby and coil+MD development.

Just implemented some very interesting features. I am going to analyse the standard concentric co-planar IB coil and will make a comparison to the current coil design. Then will analyse where the problem is and design a good working new IB-coil.

Very interesting facts will be presented soon...
Of course, German government must not use my results! They should go to the hell!

Aziz

[tiktak]

Hi

Hi,
No metter Aziz.
I was good Idea.
Maybe the probleme is in compensation coil?
Please try to simulate this coil.I wanned to try it from long time but dont have data.
Thanks

[Aziz]

Hi,
No metter Aziz.
I was good Idea.
Maybe the probleme is in compensation coil?
Please try to simulate this coil.I wanned to try it from long time but dont have data.
Thanks

Hi tiktak,

I am just working on the fundamental coil design problem. I am close to solve and crack this. Your proposal is allready in my wish list for analysis. Also many other coil types will be analysed in the future, to go on with the new optimal coil. As I figured out the basic principles, the development of the good coil will go faster then.

Anyway, this coil proposal was never a waste of my time. It was an entry and a lesson, to understand the principles better. It relates also to PI coils.

Has anyone figured out the sensitivity to a fixed given target and variable coil diameters with fixed number of turns? This could help me, to proof my results.

For all, who wants to experiment with coil diameter, magnetic field strength at a given height z, see attached files.
Aziz

[tiktak]

Hi,

Hi,
Ok then.
I am very curies to see the results of the simulation and to see your critical breaktrough!
Wish you luck.

[Aziz]

The reason, why I investigate into the magnetic field strength decay is following:
- on some coil configurations MF decays very fast to zero even it has a local strong MF (as this proposal coil design). I didn't notice this in the past.

- looking now closer to the decay behaviour of the coil configurations, to achieve a better depth sensitivity. This is my main effort. More depth sensitivity.

I didn't look much closer to this decay in the past. But this is what sells.

So, the dominating magnetic field coil should be as big as possible. But not too much, not to loose the sensitivity for small objects. If the TX coil gets too big, the magnetic field decays also at a given height center position. Of course, the size of the RX coil matters too.

This will lead to a far-field analysis of the coil configuration. Ignoring the near-field, I am focusing on the far-field now (more depth).

Any hints are welcome.

[tiktak]

Hi,

Hi,
right strategy!!Thats whats I am talking about too!
Very good reserch.
Can wait too see the results.

[Qiaozhi]

For all, who wants to experiment with coil diameter, magnetic field strength at a given height z, see attached files.
Aziz

If anyone has tried downloading this file, you need to remove the .zip extension and extract it using WinRAR, or similar.

The reason, why I investigate into the magnetic field strength decay is following:
- on some coil configurations MF decays very fast to zero even it has a local strong MF (as this proposal coil design). I didn't notice this in the past.

- looking now closer to the decay behaviour of the coil configurations, to achieve a better depth sensitivity. This is my main effort. More depth sensitivity.

I didn't look much closer to this decay in the past. But this is what sells.

So, the dominating magnetic field coil should be as big as possible. But not too much, not to loose the sensitivity for small objects. If the TX coil gets too big, the magnetic field decays also at a given height center position. Of course, the size of the RX coil matters too.

This will lead to a far-field analysis of the coil configuration. Ignoring the near-field, I am focusing on the far-field now (more depth).

Any hints are welcome.

Metal detectors work by induction, and this is a near-field effect. What you are attempting to do is extend the range of the near-field, not perform a far-field analysis. It's probably just a terminology problem - like "complex resistance", when you really meant "complex impedance".

[Aziz]

If anyone has tried downloading this file, you need to remove the .zip extension and extract it using WinRAR, or similar.


Metal detectors work by induction, and this is a near-field effect. What you are attempting to do is extend the range of the near-field, not perform a far-field analysis. It's probably just a terminology problem - like "complex resistance", when you really meant "complex impedance".

Hi Qiaozhi,

yes, your right. I removed my Winzip. Use WinRAR for this attached file. Forgot to mention this.

Anyway, far-field as I define is from the coil radius above or from a reasonable given distance above. It is just a matter of definition and may vary of different analysis.

Impedance is a complex resistance. Complex impedance does not exist.


But I have a big question regarding coil sizes:

All the different coils (coil size) existing there for a specific brand, are they matched to have a specific inductance and resistance or differ they?
Normally, the electrical circuit is setup to operate with a specific coil inductance and resistance. As the coil size differs, also the inductance will differ. So the number of turns will be different for the coils. Or have the coils same number of windings and different inductances?
It relates also to PI coils.

I have to find the reason for the less sensitivity for small objects with big coils.

Very important question. Also for all others. Kindly regards and looking forward to know the answer.
Aziz

[B^C]

Hi Aziz,

I have watched & read your posts with great interest, thank you for the time you are spending on things for others.
I for one find it very interesting to say the least.

My take on why the larger coils lose sensitivity on smaller targets is due to the fact that the magnetic field is more concentrated with smaller coils & therefor smaller targets are found easier.
As the coils become larger the magnetic field is less concentrated & therefor it is easier to miss smaller targets if this makes sense to you.

If the larger coils were designed to have a better concentration of the magnetic field the sensitivity one would think would be equal to the smaller coils. This of course poses different issues.

Only my thoughts on this, may seem like BS to others!

[Qiaozhi]

But I have a big question regarding coil sizes:

All the different coils (coil size) existing there for a specific brand, are they matched to have a specific inductance and resistance or differ they?
Normally, the electrical circuit is setup to operate with a specific coil inductance and resistance. As the coil size differs, also the inductance will differ. So the number of turns will be different for the coils. Or have the coils same number of windings and different inductances?
It relates also to PI coils.

I have to find the reason for the less sensitivity for small objects with big coils.

Very important question. Also for all others. Kindly regards and looking forward to know the answer.
Aziz

If you examine Tesoro coils you will discover that they all have the same inductance value, regardless of size The resistance value is much less important. This is true for all detectors that (like Tesoro) have the tuning capacitor in the control box.

My take on why the larger coils lose sensitivity on smaller targets is due to the fact that the magnetic field is more concentrated with smaller coils & therefor smaller targets are found easier.
As the coils become larger the magnetic field is less concentrated & therefor it is easier to miss smaller targets if this makes sense to you.

Small coils present a greater overall magnetic flux density within their area of influence than a large coil. But I think the practical result is that small coils give better separation of targets, and therefore appear more sensitive. Of course, when you increase the coil size sufficiently, the flux density at the target may be reduced enough to compromise detection of the smaller items.