MOM for open boundary???

Hi, every one.
I am now trying to learn using mom to solve some EM problem. Now I have a question about the EFIE for the open boundary condition.

Well, some literature writes that the EFIE induced surface current for open boundary represents "the vector sum of the equivalent current densities on the opposite side of the surface".

I am not sure what's the exact meaning of it... so for the open-boundary condition, for example: a metal patch, the current distribution got from MoM represents the actual condition or just the equivalent case?

Thanks in advance.

Hi,

to know the meaning of this sentence, I will give you a simple example:
imagine we have a metal sheet of small thickness, you have two options,

1. either to treat it as a box with small thickness, which will give you a lot of unrequired unknowns, but the current would be the same as in the real case (within the accuracy you choose according to number of elements, basis functions, etc .. , of course).

2. you treat it as a zero thickness sheet. in that case the current on one element would be the mean of the two currents, in that case you would get the equivalent problem, which should give a result very near to the actual case, concernming the fields, but not the actual current. i.e. this would be the equivalent case.

hope this might help
best regards,
Adel_48

Adel_48, well, I think I got the idea of you, but I am still a little wondering about the question. So taking a matal sheet for example, when the exitation is the incident wave on top of it, then the open boundary EFIE model the surface current on both side of the sheet, then the fields on either side are exactly the same... does it coincide the actual physical condition??? Thanks~

Hi winglj,

Alright, I will tell you a small example. if you had a sheet with certain thickness in the xy plane, then there would be a current in the z direction at the sheet edges, and the normal current at the edge is not zero. In the MoM model, of zero thickness, you assume the normal current at the edge is zero.

So, for in this example, the excitation is the same, but the boundary conditions are different. That is why the model is not exactly as the physical problem.

By the way, these were the same questions I was asking when I started to learn the moment method :)

Best Regards,
Adel_48