Advanced PI coils

[Aziz]

Yes, you said:yet I wish to know how much exactly. In case it breaks the 40dB barrier - I'm very happy.

Yes I know. This was a wrong assumption however. But it isn't possible to achieve both features.

You can't get even a 40 dB rejection with perfect AI coils. 20-30 dB is possible.
Aziz

[Davor]

Yes, you said:

If we slightly make the inner RX- coil bigger, we could achieve the IB balance + AI feature.

yet I wish to know how much exactly. In case it breaks the 40dB barrier - I'm very happy.

[Aziz]

I mean this one:


I'm interested how much improvement is there with outer coil being 0.8Tx. If unbalanced portion falls below 100mV - this is it! It would provide over 40dB suppression either way. And besides, if inner coil is made squeezable, I can obtain perfect balance in a jiffy - just about the easiest thing to make of them all.

...

@Sergey_P, please observe Aziz' avatar that's made with his software. It is very realistic.

The results were already on the 0.8TX unit size for RX+. RX- being RX+/sqrt(2) (=0.8TX/sqrt(2)) unit size. No chance to make the coil performing well for both AI + IB conditions at the same time.

Aziz

[Aziz]

Biot-Savart-Laplace ... without field objectives...

Yes, Biot-Savart, Maxwell equations, Faraday's Law.
Aziz

[Sergey_P]

Aziz

Biot-Savart-Laplace ... without field objectives...

[Aziz]

Avatar picture

I've found my bigger avatar picture finally ... *LOL*
Note, there is a smaller coil in it:


I'm lazy to change it. I'll keep it.
Aziz

[Aziz]

target response or magnetic field Tx ?

Well, I can calculate much more:
- Inductivity
- Magnetic Flux
- Induction
- Self induction
- mag. field strength/density
- Coil couplings
- Induction balancing
- Parameter sweeps (for optimisation)
- Target related responses
- Sensitivity maps
.. and more

The reason, why I don't give/sell the coil software?
Avoiding anyone (particularly the patent-trolls) patenting good coil ideas, found/calculated by my software. I can guarantee, that these ideas will be published in the public domain.

If you plan something to patent, don't ask me doing anything for it/you. Keep it totally secret from me. But if I'm getting interested in it by mentioning an early idea, I very likely will work on it and if there is something valuable, I'll immediately publish the idea before you can write the patent application.

The "MadLabs Inc."(c)(r)(tm) isn't interested in patenting anything or making profits. I own 42 billion shares of "Madlabs Inc."(c)(r)(tm). I'm scheiss rich!!!

Aziz

[Davor]

On the contrary, it is only a presentation of very precise vector math behind. A picture by itself is just a nice presentation. If you ever need some very accurate simulation of a real thing, just ask Aziz politely.

I had some brief encounters with femm, and it was a pain. Aziz rules!

[Sergey_P]

Aziz' avatar

beautiful, but useless...

[Davor]

Help me please. I have absolutely no idea, what you mean by that.
Aziz

I mean this one:

Ok, an IB case just calculated:
TX: 1 unit diameter, turns count any
RX+: 0.8*TX unit diameter, 50 turns
RX-: RX+/sqrt(2) unit diameter, 125 turns for IB (optimal for AI = 100 turns)

I'm interested how much improvement is there with outer coil being 0.8Tx. If unbalanced portion falls below 100mV - this is it! It would provide over 40dB suppression either way. And besides, if inner coil is made squeezable, I can obtain perfect balance in a jiffy - just about the easiest thing to make of them all.

...

@Sergey_P, please observe Aziz' avatar that's made with his software. It is very realistic.

[Sergey_P]

3D math

target response or magnetic field Tx ?

[Aziz]

You do the calculations of induced emf in a plane (2D)
I did the calculation of sensitivity to the ground in volume field (3D, approximation of - cone)

3D math. Coils can be arranged arbitrary.
Aziz

[Sergey_P]

You do the calculations of induced emf in a plane (2D)
I did the calculation of sensitivity to the ground in volume field (3D, approximation of - cone)

[Aziz]

..
Since you must have the model already at hand, what is the mismatch of Tx : Rx+ = 1:0.8 ?
..

Help me please. I have absolutely no idea, what you mean by that.
Aziz

[Davor]

A decompensating coil is in effect the same thing as ruining the ground response balance by other means. Unfortunately

Hi Davor,

in the example above with with RX+ N=50, RX- N=100 (125 optimal for IB):
TX: 300 µH, 1A coil current, f=10 kHz
Induced voltages:
RX+: -13.399 V
RX-: +10.707 V
Sum: -2.692 V
Too much for an IB coil IMHO.
Aziz

Excellent! Thank you.
I simply needed a measure to it. So roughly (+ here - there) I have some 10% mismatch or -20dB in balance. Or if balanced I'd have -20dB in interference attenuation. That's something to start with.

Since you must have the model already at hand, what is the mismatch of Tx : Rx+ = 1:0.8 ?

...
My final goal will be a real differential coil in back to back DD configuration and a 4 quadrant Rx, but in meantime a coil with ~40 dB interference and ground suppression seem a very nice idea.