About the situation, the hoped achievement would be a

  • AC electromagnet(can be ADC)
  • mid/high frequent, range between a few hz to around 100khz, asumed frequency around 16khz, capable of changing for tuning.
  • there is only one direction in which the magnetic field is needed, so a laser-like magnetic field would be optimal
  • it is meant as a long range magnet, not as a radio, so it needs to keep relative strength, super far range is not as important as the strength it has at a certain range.
  • it is meant to target metal objects which are relatively small and lightweight compared to the coil.
  • it doesn't matter if it pushes, pulls, or just energizes,vibrates,or heats the material. However optimally seen it could pull metal objects towards it.

the question how to make a electromagnet that projects it's magnetic field in a certain direction. the main reason is to extend the range of the magnet in one specific direction, the other sides of the magnet do not need to have a magnetic force, there is only one specific side in which the magnet needs to have a magnetic field.

My current ideas, some of these I have made and worked with passive magnets, however I hope greater results now. one is not listed on the drawing, this one consists of magnets next to each other which are all faced in the same direction, in my test I made 2 such grids of 5*5 passive magnets and I stacked the layers on top of each other with a small gab between the 2 grids. this worked to reasonably increase the range, in the direction of the flat sides of the grid.

enter image description here

idea 1 uses a bunch of magnetic loops all faced in the same direction in a linear order compared to each other, the mod version adds some similar towers mounted to form a parabola like shape to press the force of the main center magnet into one beam.

idea 2 is based on the design where passive magnets are mounted on a sphere to keep one magnetic field inside of the sphere, and the outside of it the other polarity, this is on one point left open, and in one case adds in a reversed magnet in that location, I replaced it with electromagnets in the design,. this is supposed to work somehow similar to a cathode ray. this design is drawn in 2d but is 3d since the entire sphere is covered in magnets except for one point. idea 3 is a variation of this

idea 4 is a bunch of electro magnets in a parabolic shape.

idea 5 is a magnet in a cone shape with a parabolic reflector behind it. idea 6 is based on a dipole antenna, but it uses coils instead of antennas and it is a closed loop. this generates one pole in the center and one one the outsides and switches it idea 7 is 6 but with could not only left and right, but it makes it a complete 2d circle

as a next thing what shape of coils/what geometry would be best to use. the bleu lines show the direction of the used magnetic field. S1 is about the straight/cone shape of the coil, S2 is about the width to length ratio, S3 is about windings around or behind eachother.enter image description here

  • $\begingroup$ Re, "a laser-like magnetic field would be optimal" But unfortunately, that's not how magnetism works. en.wikipedia.org/wiki/Magnetic_dipole $\endgroup$ Jul 30, 2021 at 14:29
  • $\begingroup$ Between the poles of an otherwise bended to a donut magnetic core you get the highest magnetic field. de.wikipedia.org/wiki/Luftspalt_(Magnetismus) (only available in German) $\endgroup$ Aug 1, 2021 at 6:15
  • $\begingroup$ So kind of like a capacitor and a resistor? where the gab prevents the direct "flow/charge alignment flow" of the magnet to move properly in a circle which gives some kind of a capacitor effect but for the magnetic field, and prevents current flow in the core while keeping aligned with the field. the resistor part is because like a conductive wire with a resistor, most power would be lost in the resistor, and the core would be like that conductor, the gab like the resistor. the coil would be the power source. this is a speculation of how I estimate it to work. $\endgroup$ Aug 2, 2021 at 11:52

1 Answer 1


When viewed from a distance, the field from any magnet is a dipole field, which at a distance drops off as the cube of the distance. This does not bode well for forming a magnetic field into a beam.

  • $\begingroup$ however it should be possible to deform that dipole field. for example if you first start with a perfect circle than could it be possible to stretch it in one direction making it more narrow in the other? $\endgroup$ Jul 31, 2021 at 17:19

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