A bunch of questions regarding radially magetized ring magnet.

[PolaczekCebulaczek]

Gyula thanks for pdf file, so in radially magnetized ring/unipole magnet there are almost no field lines extending , fascinating...

phoneboy your idea sounds interesting but I'm not sure if I understand the picture correctly, you meant something like this:

so two opposing poles-coils should produce N N outside and S S in the middle of the ring?

here is a method to make magnet using pancake coil but I cant see why this should work.

http://overunity.com/6856/how-to-simply-make-a-radially-magnetized-magnet-a-2d-magnetic-monopole/

[phoneboy]

This might help more, whipped up an image of the top half of the mold with the coil placed and the ring.

[gyulasun]

Gyula thanks for pdf file, so in radially magnetized ring/unipole magnet there are almost
no field lines extending , fascinating...
.....

Your statement is misunderstandable how you mean so let me tell: field lines do extend
from an unipole ring magnet but the green viewing foil shown in pictures are somehow
mask them, not good quality pictures for unipole example, unfortunately. 
Magnetic lines of flux surely come out from the body of such ring magnets, especially
at the edges where the perpendicular sides meet but of course at the in-between surfaces too. 

You can imagine this when you consider a long rectangular bar magnet, magnetized length wise,
the lines of flux extend from mainly at the ends in quasi every direction from that 'uni pole' 
a long enough bar magnet has at its ends. 
In case of such radially magnetized ring magnets the smallest number of flux lines that extend
or come out from them can be found in the virtual center circle of their thickness.  (for a long bar
magnet this area can be found in the center or the middle of the full length as you surely know)

Gyula

[PolaczekCebulaczek]

phoneboy thank for 3d picture now I understand, NN poles would meet inside the ring and SS outside the ring.

gyulasun soo in very center of the ring there should be no magnetism ? (due to repulsion?) if I put a compass in exact center of the ring and if needle is not reaching field lines then the compass should point only to magnetic field of the earth, right??

[gyulasun]

...
gyulasun soo in very center of the ring there should be no magnetism ? (due to repulsion?)
if I put a compass in exact center of the ring and if needle is not reaching field lines
then the compass should point only to magnetic field of the earth, right??

No offense but I did not write, did not mean or did not imply that there is no magnetism in the
very center of a radially magnetized ring magnet.
Read my posts again, perhaps there is some language barrier?

Consider the following setup: you have say 4 identical bar magnets, each 5cm long, with 5x5mm
cross section, magnetized length wise. Say you fix these magnets onto a CD disk at 12, 3, 6 and 9 o'clock
positions so that their North pole ends point radially towards the disk center and each magnet North end is say
2 cm away from the very center point of the disk. Now try to increase in theory the number of bar
magnets you would also place radially to fill up all the space and get a radially magnetized ring
magnet that would have an OD of 7+7cm and an ID of 2+2cm, ok?

Now ask yourself: can the very center point or line of this setup free of magnetism?

My answer is no. There must be magnetism in the very center too. Very probably the strength of the
North pole fields in the very center is the smallest but not zero compared to any other point within
the virtual 2cm+2cm inner diameter area of this setup.

Generally speaking, maybe there are no lines of flux in some very narrow area between two
facing like poles (think of two block magnets in this example now) that are pushed together with a
strong force: the lines of flux are said to be pressed out from within the nearly or fully touching facing
surfaces of the two like poles BUT this is not an equivalent example to be compared to the very center of
a radial ring where there is always the 'distance' of just the inner ring diameter between any facing
like poled points, ok? And like poles cannot fully cancel within the inner diameter of a radial ring:
the squizing-out force of the like poled lines of force present in the ID area or space of the ring is not
enough to sweep them all out.

Now imagine that you have a radially magnetized ring magnet with an ID of say 5 cm, with an OD of say
7 cm and the thickness or height of such ring would be say 6 cm. If you could place a say 3 cm long
compass needle into the exact center line of this ring magnet, then I think the compass would stay in the
very center line.
A better example would be: instead of the compass you would use a say 3 cm long cylinder magnet
that would have an OD of say 2mm and would be magnetized length wise, then this cylinder magnet
would also stay in the very center line I think.

Hope this explains and puts an end for your dilemma... If still in doubt, please try to assemble such
radial ring magnet setup from cheap ceramic block magnets magnetized lenght wise and check it.

Gyula