"PagCal" wrote in message
...
Has anyone looked at patents:

US4429280 - Apparatus for DEmodulation of Modulated Curl-Free Magnetic
Vector Potential

US4429288 - Apparatus for modulation of a Curl-Free Magnetic Vector
Potential Field

US4432098 - Apparatus for transfer of Information by means of a
Curl-Free Magnetic Vector Potential Field

US4447779 - Apparatus for Determination of a Receiving device utilizing
a Curl-Free Magnetic Vector Potential Field.

US4605897 - Apparatus for distance determination between receiving
device utilizing a Curl-Free Magnetic Vector Potential Field.

US4491795 - Josephson Junction Interferometer Device for detection of
Curl-Free Magnetic Vector Potential field.

These were patented by Raymond C. Gelinas of Concord MA, and assigned to
Honeywell, Inc.

I have no idea of the range of this type of communications system,
frequencies used, or even the bandwidth you could achieve.

What is Curl-Free transmission anyway?

lets see, if the magnetic field doesn't have any curl then there is no
electric field created. so basically you have a static magnetic field. so
modulating it doesn't make much sense as then it would have a non-zero curl.
as far as receiving it there are devices to detect static magnetic fields,
and a josephson junction may be able to do that.