Symmetry in Electromagnetics

as you know , according to maxwell equatoins the electromagnetic fields depends to spitial coordinates every where and hence this sentence seems correct that the electromagnetic symetry needs the giametrical symetry . but it is better you explain more what do you mean?

I meant exactly what you have told. If geomtrical symmetry exists then you "may" or "may not" have EM symmetry but if EM symmetry exists then you "must have" geometric symmetry. In a sense I mean that when some one says EM Symmetry exists in a particular problem, then it implies that the structure must be geometrically symmetrical.

If the structure being modeled has a plane with field on one side of a plane being the mirror image of the field on the other side,take advantage of the symmetry.

"The plane of symmetry must cut through the middle of all the ports applied to the structure. Otherwise,there may be only phsycal symmetry without electomagnetic symmetry. The structure must be on one side of the symmetry plane"

Yes, for EM symmetry, you must have geometric symmetry. In addition, you must also have excitation symmetry. For example, if there port on one side of the plane of symmetry, there must be a second port on the other side, and it must be excited symmetrically (+ or -) so that the two ports are treated as one port (push-pull, or push-push, see SonnetLite documentation for more detail if this is not clear). In addition, for time harmonic (i.e., RF/microwave) the surfaces about which you have symmetry must be planes (i.e., not lines, not cylinders, not spheres, etc.).

Hi ,

I have found from Ansoft simulations that even though our design is exactly symmetric in geometry, we dont get the expected symmetric radiation pattern.
I could nt figure out the reason for this (probably something to do with meshing ?)

assuming Em existed in symetry is how maxwell came up with his unification of field theory.

Mr.Cool

Could you highlight on the symmetry aspect in maxwells equation ?

I want to say some thing there is two necessary consithions for EM symmetry
1- Geometric symmetery
2- charge distribution symmetry
if any one of these conditions fail we say may or may not there's EM symmetry
thanks
Amr

the symmetry aspect in maxwell's equations comes from every physisits deep seeded belief in symmetry. they go LOOKING for it and practically force its condition. it stems from the conservation of energy and universe in a nice harmonic balance.. pleasant thoughts. don't get me wrong, conservation of energy is the only law of physics that isn't broken in some way. one needs only to PROPERLY define which system of reference is containing this conservation of energy.

maxwell believed (on a hunch) in the conservation of energy and therefore symmetry. look into his Displacement Current addition to EM theory and you will see it quite clearly.

Mr.Cool
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