Author Topic: Coil size and ground effect  (Read 3016 times)

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Filternozzle

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Coil size and ground effect
« on: November 20, 2015, 02:56 pm »
In your experience, which is affected by the ground the most, larger or smaller coil?

SuchMuch

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Re: Coil size and ground effect
« Reply #1 on: November 20, 2015, 04:50 pm »
No doubt larger coil is more affected by ground.
Frequency is another side of the coin: low frequency is less influenced by ground than high frequency.

 

detecting_deano

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Re: Coil size and ground effect
« Reply #2 on: November 20, 2015, 05:19 pm »
Another vote for the large coil being affected more

13oots2

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Re: Coil size and ground effect
« Reply #3 on: November 20, 2015, 06:46 pm »
Think of the coil as an antennae, with a bigger antennae you receive a stronger signal, elementary physics my dear Watson  ;)
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Filternozzle

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Re: Coil size and ground effect
« Reply #4 on: November 20, 2015, 07:06 pm »
Are you answers based on actual experience of using two coils, one larger/smaller than the other on the same ground and noticed the difference?

SuchMuch

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Re: Coil size and ground effect
« Reply #5 on: November 20, 2015, 07:16 pm »
Are you answers based on actual experience of using two coils, one larger/smaller than the other on the same ground and noticed the difference?
E.g. 1: I was hunting with 13"@3F (12 kHz was chosen), then rain started and it was raining for 3-4 hours. I decided to GB once again and was not able to succeed with GB because of electrolyte grounds (salty grounds). I got my detector equipped with 6"x10"@20 kHz and performed GB easily.

E.g. 2: Rough plough.  13"@3F (12 kHz chosen) produces falsing, once 6"x10"@20/14 kHz is equipped falsing is gone. 

gc-1023

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Re: Coil size and ground effect
« Reply #6 on: November 20, 2015, 07:36 pm »
without doubt bigger coil will register more ground effects .
think of your target as a percentage of area covered by coil .
a 13" coil probably scans 10 times more ground than a 5" coil.thats 10x as many minerals it has to cancel out
hence my claim big coils are rubbish if not ground balanced properly to site conditions  .
http://www.metaldetectingworld.com/search_coil_size_applications.shtml
also type of coil is important ,2d coil handles ground minerals better than concentric coils .

SuchMuch

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Re: Coil size and ground effect
« Reply #7 on: November 20, 2015, 09:10 pm »
http://www.metaldetectingworld.com/search_coil_size_applications.shtml
Very narrowed overview.

I would say coils size should be chosen in connection with level of iron contamination mostly. Ground mineralization and rough plough could be handled perfectly by using different tricks and filters. Large coil means more area you can cover (on semi trashy/clean sites) and consequently meet more finds.

Level of iron contamination is only the factor you cannot overcome with large coil

gc-1023

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Re: Coil size and ground effect
« Reply #8 on: November 20, 2015, 09:49 pm »
one ground effect i have noticed in my field is horse pee.
the grass looks scorched and there is positive false signals there .
i,m assuming it is urine thats causeing the falsing
anyone else notice this .

Gary

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Re: Coil size and ground effect
« Reply #9 on: November 20, 2015, 09:56 pm »
The smaller coil may work opposite to what we think. Bad ground could saturate the coil as a very large target.
Also it could depend on what machine you are using, VLF, IB, PI

It's something to consider

impos1

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Re: Coil size and ground effect
« Reply #10 on: November 20, 2015, 10:02 pm »
one ground effect i have noticed in my field is horse pee.
the grass looks scorched and there is positive false signals there .
i,m assuming it is urine thats causeing the falsing
anyone else notice this .

Possibly a load of iron in the urine
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SuchMuch

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Re: Coil size and ground effect
« Reply #11 on: November 20, 2015, 10:26 pm »
one ground effect i have noticed in my field is horse pee.
the grass looks scorched and there is positive false signals there .
i,m assuming it is urine thats causeing the falsing
anyone else notice this .
conductive spot that has different GB