Move the antenna further away. then use correction factors to calculate
what it would have been at the original distance.
Magnetic fields decrease as the inverse cube of the distance. So just apply
a correction factor to "boost" the amplitude back up. For example, twice
the distance away means the signal will look 1/8 as much or around 18dB
smaller.
Of course, that assumes the source is a magnetic dipole AND your original
measurement distance is at least 3 diameters (diameters of the sensing loop
AND diameters of the source loop) away to begin with.
[ Also, conductive surfaces and magnetic materials need to be out of the
field of interest. Make certain the minimum distance to such "interference"
is at least 3 times the distance between what you're measuring and your
sensing loop. ]
If the above assumptions don't hold, come back at me.
- Robert -
Robert A. Macy, PE [email protected]
408 286 3985 fx 408 297 9121
AJM International Electronics Consultants
619 North First St, San Jose, CA 95112
-----Original Message-----
From: KC CHAN [PDD] <[email protected]>
To: < <[email protected]>
List-Post: [email protected]
Date: Monday, September 24, 2001 12:19 AM
Subject: Active loop antenna overload
>
>Dear All
>
>When doing the magnetic field measurement by a active loop antenna, what we
can do if we find the loop antenna is saturated/overloaded? Is there any
ways that we can do to overcome this?
>
>Best Regards
>KC Chan
>
>
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