And any electrical engineer you should familiar with Maxwell's equations. In electronic engineer we work with electronic or photonic or hybrid deveice and gate of understanding this deveice is electromagnetic and solid state physics and some electronic devices books.So every model that we see in electronic deveices is derived from Maxwell's equations. We in Bsc degree we solve electromagnetic question in a analytical methods, but in real world we can not use analytical methods,So we should swtich to methods course numerical analysis.So in this blog post we want to discuss about numerical method to solve Maxwell's equation for different problems.

**FDTD:**

Finite-difference time-domain or Yee's method (named after the Chinese American applied mathematician Kane S. Yee, born 1934) is a numerical analysis technique used for modeling computational electrodynamics (finding approximate solutions to the associated system of differential equations). Since it is a time-domain method, FDTD solutions can cover a wide frequency range with a single simulation run, and treat nonlinear material properties in a natural way[1].

**Software FDTD:**

**FEM:**

The finite element method (FEM) is a numerical method for solving problems of engineering and mathematical physics. It is also referred to as finite element analysis (FEA). Typical problem areas of interest include structural analysis, heat transfer, fluid flow, mass transport, and electromagnetic potential. The analytical solution of these problems generally require the solution to boundary value problems for partial differential equations. The finite element method formulation of the problem results in a system of algebraic equations. The method yields approximate values of the unknowns at discrete number of points over the domain.[1] To solve the problem, it subdivides a large problem into smaller, simpler parts that are called finite elements. The simple equations that model these finite elements are then assembled into a larger system of equations that models the entire problem. FEM then uses variational methods from the calculus of variations to approximate a solution by minimizing an associated error function[2].

**Software FEM:**

Other Software can be saw on this link.

**MOM:**

In statistics, the method of moments is a method of estimation of population parameters. One starts with deriving equations that relate the population moments (i.e., the expected values of powers of the random variable under consideration) to the parameters of interest. Then a sample is drawn and the population moments are estimated from the sample. The equations are then solved for the parameters of interest, using the sample moments in place of the (unknown) population moments. This results in estimates of those parameters. The method of moments was introduced by Karl Pearson in 1894[3].

**Full Wave Analysis:**

I from this link,i shared definition of full wave analysis:

A simple explanation that facilitates the understanding is: full wave analysis is to solve the complete set of Maxwells equations without any simplifying assumptions. Usually the fields described by the equations are time-variant/frequency-dependent. Compared to full wave analysis are some methods such as Quasi-static analysis, where the Maxwell's equations are simplified first(the fields are assumed time-invariant/frequency-independent).

Full-wave analysis is often used to analyze electrically-large structures(physical size is much much larger compared to wavelength), in other words, doing high frequency analysis. Some famous full-wave solvers are: Ansoft HFSS, CST Microwave Studio

Quasi-static analysis is suitable for electrically small structures(usually phsical size is assumed to be less than 1/10 wavelength or 1/6 wavelength or… depends on applications as can be seen from a lot of text books). One of the most famous solver is: Ansoft SpiceLink which is also known as Q2D/Q3D

**Software Full Wave Analysis:**

So modeling a electromagnetic problem is very important so we should use a numerical method for solve our problems. i share a link that is describe more importance finding best method for our problems. please see this link.

So i find a link that describe that most popular software electronic and communication engineer what's method using for solve problem that i shared a quotation[4].

HFSS and CST are 3 D EM simulators based upon different computational techniques. HFSS is based on Finite Element Method (FEM) which is more accurate for designing antennas while CST is based upon Finite Integration in Technique (FIT) and is also popular among antenna designers due to ease in simulations. However results of both the simulators are not same becaue of different computational techniques involved. HFSS results are close to experimental results with more insight into the structure available. ADS is used for circuit co simulations where active components are also involved. It can be used for planar antennas as well and is based upon MoM (Method of Moment). AWR, i used while simulating different kind of filters but dont know the details of this software.

What is the difference between AWR, HFSS, ADS, CST?. Available from: https://www.researchgate.net/post/What_is_the_difference_between_AWR_HFSS_ADS_CST [accessed Jul 20, 2017].

Some Good info from this link:

The file describes comparision these methods very well.

Simple dielectric structures with MoM and its extensions.

Electrically large structures with MLFMM.

Complex dielectric structures with MoM-FEM hybrid.

**Conclution**:Every software use a model and numerical method and they had result to real world to special problem, So we should before simulate, we should select proper software for our prolems, this point is very important in practical works.