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Offline AK48Topic starter
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« on: August 12, 2017, 06:37:12 am »
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hello , a little question on magnetic field , can we shape the magnetic field of a coil by diversifying the form of the coil ? thank yoou
AK48

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« Reply #1 on: August 12, 2017, 06:57:08 am »
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   Yes, Coil Shape and geometry does effect the magnetic fields, shape, density and direction.  Just as a Antenna's geometry can effect RF magnetic radiation .

Do a gOOgle and tons of information come up.


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Offline AK48Topic starter
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« Reply #2 on: August 12, 2017, 01:13:02 pm »
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hello and thank you , i was afraid it was no possible .

Posted on: August 12, 2017, 01:07:26 pm
hello ! anothet question , can you show me sketch of magnetic field of vlf and p.i  please .

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Offline GoldDigger1950
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« Reply #3 on: August 12, 2017, 02:25:45 pm »
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Your best option is to develop your own Smith Charts. You can search here in the search block at the top right corner and find a description of a probe you can use with your sound card that can help you to read your fields. The Smith Chart can be found using Google. Each coil you make can then be tested to show your field on the chart.

You can also download this:

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Or read this topic:

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http://www.thunting.com/smf/metal_detectors/transmit_coils_testing_procedures-t18215.0.html;highlight=




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« Last Edit: August 12, 2017, 02:35:55 pm by GoldDigger1950 » 		Logged
It's all about that moment when metal that hasn't seen the light of day for generations frees itself from the soil and presents itself to me.
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« Reply #4 on: August 12, 2017, 03:20:48 pm »
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Quote:Posted by AK48
hello , a little question on magnetic field , can we shape the magnetic field of a coil by diversifying the form of the coil ? thank yoou
AK48


The short answer is, not easily. A detector coil is not an antenna in the classical sense, it is a transformer. It operates in the near-field, not the far-field, so everything you read about antenna design and patterns does NOT apply to detector coils. There are ways to design near-field coils that are better "focused" or less bi-directional but those designs are invariably hard to build and unstable; slightest bumps will cause falsing.

The magnetic field pattern depends on the coil, not whether it's connected to a VLF or PI transmitter. BTW, Smith charts have nothing to do with plotting magnetic fields; they are used for plotting complex impedance and solving impedance matching problems.


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« Reply #5 on: August 12, 2017, 04:44:16 pm »
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  Carl-NC said "It operates in the near-field, not the far-field, so everything you read about antenna design and patterns does NOT apply to detector coils."   Ah but like  you can shape a RF Radiation Lobe With Antenna Geometry, you can affect the shape the Magnetic Field with the Coil Geometry as well.  


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Offline AK48Topic starter
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« Reply #6 on: August 12, 2017, 05:18:32 pm »
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hello , i understand very well what do you explain me and i'm gonna read and test , thank you very much for this new lesson , tonight , i'm gonna sleep clever than yesterday , thanks again , nice from you .
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« Reply #7 on: August 25, 2017, 11:48:14 am »
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Quote:Posted by AK48
hello , a little question on magnetic field , can we shape the magnetic field of a coil by diversifying the form of the coil ? thank yoou
AK48

Coils shape magnetic fields I worked on and with CRT TV remember the defection yoke on the back of an old style TV. That coil was responsible for dragging the electron been across the phosphor of the tube to generate the scan lines. And there were also focusing coils as well. How precise was that in controlling a magnetic field   
My problem is i have to many hobbies. And one of them is coils.
I get where you are coming from good thinking.
There is one design or concept I am transfixed on is the vortex coil. Generate a magnetic field like a smoke ring, think of it like this. A smoke ring can travel across a room a great distance.  But you can only blow out the candles on your birthday cake if you are very close. Look up the design of the primary coil on Tesla coil.       


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« Reply #8 on: August 25, 2017, 02:58:40 pm »
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Magnetic field is the new buzz word.
look at the new ML patent

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Abstract
A method for detecting a target in a soil using a metal detector, including: generating a transmit magnetic field for transmission into the soil based on a transmit signal; receiving a receive magnetic field; providing a receive signal induced by the receive magnetic field; processing the receive signal for producing a set of data which has effects of signals from the soil reduced therein or removed therefrom; producing at least two components of a form of at least one time constant spectrum based on the set of data; and producing, at least one indicator output signal based on the at least two components for indicating the presence and/or identity of the target when the target is within, an influence of the transmit magnetic field.



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« Reply #9 on: August 25, 2017, 04:16:02 pm »
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Dang Minelab uses $4.00 words in that thing!    Shocked

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