Improved Splitted/Spiral MONO PI Coils

[Aziz]

Hello friends,

I have really good news for you!

The real target induced response feature is only recently available to my coil software. So the analysis is a real target response. See in the GoldProspectinginOz forum for further infos and how I am making the analysis.


I have analysed the split mono/spiral coil configurations further. It shows, that the evenly distributed windings from radius 1 to radius 2 will give the best possible response. Such a coils is a typical spiral coil. The spiral coil should use the full flux area to be optimal. One might perhaps want to have a hole in the center of the coil for pin-pointing aid. As this hole does not contribute much inductivity, the benefit for pin-pointing and less weight is obviously.
The coil windings will have of course very less interwire capacitance. However, the spiral coil cannot be shielded perfectly without adding much capacitance to the shielding. The simulation shows, that an approximation of a spiral coil can be achieved by using split coils evenly distributed in the dimensions with same number of windings each. Each splitted coil can be shielded easier with less shielding capacitance and will cause less eddy currents from the shielding. The interwire coil capacitance will also be quite less (lesser than an equivalent round compact wound mono coil).

Now some comments on the chart:
I have analysed the 20" coil, as this spares some simulation time due to less flux area. But generally, the result applies also to all possible dimensions. It also applies to elliptical coils. The equivalent coil responses are shown for 10", 20" and 30".
The coil 20"+15"+10"+5" round mono means: four splitted coils with 20", 15", 10" and 5" diameter with same number of windings each.

The coil 20"+10" round mono means: two splitted coils with 20" and 10" diameter (each same number of windings).

The coil 20"-5" spiral round mono means: evenly wounded spiral coil from diameter 5" to 20" (I think ~31 turns here for 300 µH).

All coils have total 300µH (reference base). Other simulation results show (not shown yet), that changing the number of turn in each splitted coil does not give an improvement yet (to be analysed further).

Conclusions: The 20"-5" spiral coil outperforms an equivalent 30" round mono coil for the given target (20 mm diameter) up to the distance of 50 cm! The 20"+15"+10"+5" coil is almost as good as the spiral coil, which can be shielded with less capacitance.

Now I need your help to prove this by your practical measurements. I haven't the means for this at the moment. You know, I am a very very poor guy. It will be much appreciated.

Aziz

Where is chemelec?
I think, this finding will enjoy him.

[chemelec]

Interesting Chart!
And Just to let people here know, "I replied to Aziz directly, in an email he sent me".

Also, for anyone interested, I have developed a spot on my right lung, Possibly Cancer.

I will be going to see a Lung Specialist on Feb 23.
Than hopefully I will know better whats happening.

However, I believe this is Not too Serious, but it May require Surgery and whatever else.

So I haven't been doing too much lately and I'm Not accepting any requests for parts or PCB's till I know what is coming.

Take care...Gary

[Qiaozhi]

Good luck Gary.
Hope it turns out not to be anything serious.

[Unregistered]

Interesting Chart!
And Just to let people here know, "I replied to Aziz directly, in an email he sent me".

Also, for anyone interested, I have developed a spot on my right lung, Possibly Cancer.

I will be going to see a Lung Specialist on Feb 23.
Than hopefully I will know better whats happening.

However, I believe this is Not too Serious, but it May require Surgery and whatever else.

So I haven't been doing too much lately and I'm Not accepting any requests for parts or PCB's till I know what is coming.

Take care...Gary

Hey! Nose up! That still does not mean a thing! Is it node or notch, whatever it is, only in few percents can be tumor. Are you a smoker? If yes than dont worry, i am also and i do have so many spots and nodes in my lungs yet none of those is tumor.
Especially at smoker lungs there are a lot of pneumonic mists and spits and possible a few cavities. I have been seen many x-ray shots so far. Terrible to look those. Yet human tissue is a miracle. Once you gave up of smoking and turn to more healthfull life all the problems start to solve in time. So, dont drop in depression. First, it is probably not a tumor, second ; even if it is, it still have enough time and methods to be solved and cured.Look at me, i am still smoking after 26 years (2 packs daily) and dont have slitest intention to stop. If i got something problematic; will not care at all. Maybe it will push me to stop smoking in time. But smoking is not so bad thing as "new order" trying to persuade us in last 20-30 years. Much more bad things you collecting from modern way of living, junk food, radio frequencies, cell phones, everyday stress. Least you get from cigarretes. Trust me. And nose up. There are so much new projects to be done, waiting for you. Look Dell as an example. He was in problems and now (thanks God) he is not any more. Just be a fighter and dont worry.
Of course respect your doctor also. But do not let him to missuse your fear!

[Tinkerer]

Good luck Gary

Good luck Gary. Keep us updated. We need you here.

Tinkerer

[Tinkerer]

Spiral wound coils

Aziz,

very nice coil response charts.

I have experimented some with spiral wound coils. They have good pinpointing and good depth.
However, the footprint at depth is very narrow, so what looks excellent for air tests, is not so good in the field.

I abandoned spiral wound coils.

A large TX coil and a smaller RX coil give me better results.

A question about your charts. How do you manage to pump 1A into a 300uH coil at a rate of 1Mhz? Is this realistic?

For the target a more realistic target would have 10 to 100 TC. I am sure the response would be somewhat different.

Keep up the good work.

Tinkerer

[nelson]

Hey Gary, has a told you before on the phone, we are praying for your health.
We know you will pass this, cause you are a very optimistic person and a good man.
Take care and thrust in God
Nelson and family

Interesting Chart!
And Just to let people here know, "I replied to Aziz directly, in an email he sent me".

Also, for anyone interested, I have developed a spot on my right lung, Possibly Cancer.

I will be going to see a Lung Specialist on Feb 23.
Than hopefully I will know better whats happening.

However, I believe this is Not too Serious, but it May require Surgery and whatever else.

So I haven't been doing too much lately and I'm Not accepting any requests for parts or PCB's till I know what is coming.

Take care...Gary

[chemelec]

Hey! Nose up! That still does not mean a thing! Is it node or notch, whatever it is, only in few percents can be tumor. Are you a smoker? If yes than dont worry, i am also and i do have so many spots and nodes in my lungs yet none of those is tumor.
Especially at smoker lungs there are a lot of pneumonic mists and spits and possible a few cavities. I have been seen many x-ray shots so far. Terrible to look those. Yet human tissue is a miracle. Once you gave up of smoking and turn to more healthfull life all the problems start to solve in time. So, dont drop in depression. First, it is probably not a tumor, second ; even if it is, it still have enough time and methods to be solved and cured.Look at me, i am still smoking after 26 years (2 packs daily) and dont have slitest intention to stop. If i got something problematic; will not care at all. Maybe it will push me to stop smoking in time. But smoking is not so bad thing as "new order" trying to persuade us in last 20-30 years. Much more bad things you collecting from modern way of living, junk food, radio frequencies, cell phones, everyday stress. Least you get from cigarretes. Trust me. And nose up. There are so much new projects to be done, waiting for you. Look Dell as an example. He was in problems and now (thanks God) he is not any more. Just be a fighter and dont worry.
Of course respect your doctor also. But do not let him to missuse your fear!

I Don't believe in god, But I got NO DEPRESSION HERE!

I'm Quite sure it will work out OK.

Take care....Gary

[Unregistered]

I dont beleive in God too, but i am affraid of Him much!

[Aziz]

Hi Gary,

as I mentioned in my email, I wish you good luck and that suspicion of disease won't be serious.

I want to let you know, that your coils are working better than the equivalent in size and inductivity to normal wound mono coils. Particularly, bigger coils won't miss smaller targets anymore.

Best wishes and good luck,
Aziz

[Aziz]

Hi Tinkerer,

Aziz,

A question about your charts. How do you manage to pump 1A into a 300uH coil at a rate of 1Mhz? Is this realistic?

For the target a more realistic target would have 10 to 100 TC. I am sure the response would be somewhat different.

Keep up the good work.

Tinkerer

The 1 MHz is used for the induction calculation. No magnetic flux change (no AC coil current) = no induction voltage. To get reasonable values, I took this frequency as a fixed reference value. You can take any other AC frequencies as you take it for all coils same. But you will get other target induced response voltages (dependend on the frequency).

The chart will show only the following information: Which coil design is better! Not more. So all coil configurations are normalized to a fixed exposed magnetic field energy to be compareable. Which means: E = 0.5*L*I² = 0.5*300µH*1 A² = 0.15 mJ. Don't look at the absolute induced voltages. Look only on their relation to others, which counts here.

Yes, the 1 MHz is quite realistic. Not during the TX-on but during the TX-off process (damping process). If you have a 400 V flyback voltage and a damping resistor of 400 Ohms, you get 1 A coil current flow at that moment. The slew rate of the coil current (first derivation of coil current) gets quite high during damping process, which may exceed the 1 MHz frequency just in the beginning of the damping process.

I have used simple coil targets with given diameter (20 mm) and 1 mm wire core. Using time constant for the target is irrelevant in the comparison.

Some notes on the response voltage:

A primary magnetic field will be exposed from the transmitter coil (TX) (L=300µH, I=1A, f=1 MHz). The target induces a voltage. A current flows through the target depending on the induced voltage (simulating eddy currents) and exposes a secondary magnetic field. The transmitter coil becomes a receiver coil and induces voltage caused from the secondary magnetic field. To see only the target response, I have omitted all self induced voltages (particularly in the TX coil).


Aziz