# Explanation of MOM and FEM (resources provided)

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#### cyprus

##### Banned
what is MOM and FEM

while i was reading the topic
i want to ask now when i use a software such as NEC OR HFSS or matlab or pascad it says that NEC uses MOM while HFSS uses FEM; what kind of method did you use in matlab :
so what is MOM,FEM CAN İ HAVE SOME DETAİLS ABOUT İT :? THANKS ALOT AND What about the other programs

#### Jone

Re: what is MOM and FEM

When you studied your em-theory you probably solved everything analytically. However, real world problems cannot in general be solved this way. Instead we have to solve them numerically. This creates a new huge area of em, computational electromagnetics (CEM), also called Electromagnetic Modeling. As you know, all macroscopic electromagnetic phenomena is described by the Maxwell's equations. So with CEM we solve the Maxwell's equation numerically and this is what the em software like HFSS and NEC does. There are different methods to use, FEM, MoM and FDTD are the most common ones. There is no method which is perfect for all problems. As an example, HFSS uses the Finite Element Method (FEM). With this method we divide the structure into Finite Elements, most often some triangular structure. Then solve the equations for every corner point, that is, determine the fields there. It is important to understand the methods so that you know how to solve different problems efficiently. For more information I suggest you read some book about CEM.

armik

Points: 2

### armik

Points: 2

##### Full Member level 2
Re: what is MOM and FEM

Agilent has both MOM & FEM based EM simulators and read help documents for detailed information

armik

### armik

Points: 2

#### lekshmi

##### Newbie level 6
Re: what is MOM and FEM

MOM-method of moments

FEM-Finite Element method

these 2 mtds are used to solve Electromagnetic problems in FDTD method.

armik

### armik

Points: 2

#### kokokaka

##### Newbie level 4
what is MOM and FEM

MOM is the Method of Moment
FED is the method besed in the technique of the finits elements. for more detailed you can studie the itoh's book " Numerical thechniques for MW & MmW passive structures.
good luck

armik

### armik

Points: 2

#### peleda

Re: what is MOM and FEM

MATLAB does not have a particular mode. MATLAB is a programming language (????? is it????) . With MATLAB, you actually have to write your code yourself, so you could choose to implement it either in MOM or FEM.

Generally, you use MOM for wire like structures. Hence, the popularity of NEC for simulating wires structures. FEM has a big role for 3D structures. MOM is integral based. FEM is differential based. MOM can be used for 3D structures, but in general, it depends on the complexity of the problem.

armik

### armik

Points: 2

#### muralicrl

##### Full Member level 5
Re: what is MOM and FEM

Hi,

See the attachments on MOM and FEM.

armik

Points: 2

### armik

Points: 2

#### tyenergy

##### Junior Member level 3
what is MOM and FEM

to lekshmi:
"MOM-method of moments

FEM-Finite Element method

these 2 mtds are used to solve Electromagnetic problems in FDTD method"

what do you mean "these 2 mtds are used to solve Electromagnetic problems in FDTD method"? do you mean you combine these two methods into the FDTD method? that must be interesting

armik

### armik

Points: 2

#### peleda

Re: what is MOM and FEM

I saw that comment, and it got me thinking.
FDTD is a different method of its own. It is based on differential methods.

Lets get that sorted right now.

armik

### armik

Points: 2

#### syneyes

##### Newbie level 3
what is MOM and FEM

I have learned the FDTD and FEM
and the FDTD is easy to understand,but the code is hard to write,and very long
FEM is a little hard to understand,but it's short.

armik

Points: 2