plzzzz help me out - finte element method, method of moment

[shahzadleo7]

plzzzz help me out

Q1) Explain finte element method and method of moment and HFSS realize these methods

Q2) How do we compare the results of YAGI-UDA and Dipole antenna Radiation patttern and VSWR

 

[rrumpf]

Re: plzzzz help me out

You are asking some rather large and involved questions, and I cannot answer all of them.

The finite element method (FEM) and the method of moments (MOM) are very similar. Typically, FEM is solving Maxwell's equations throughout the volume of the device and is computing the fields. MOM is typically solving an integral equation derived from Maxwell's equations, such as Pocklington's integral equation, and is solving for currents in conductors. Each tends to describe structures by dividing them into pieces, or elements. For 2D simulations these are most often triangles and you have probably seen meshes describing the geometry of these devices. In FEM, equations are derived relating the points or edges in the element. From this, a sparse global matrix is constructed and solved. In MOM, the integral equation leads to a smaller, but full matrix which is solved.

High Frequency Structures Simulator (HFSS), if I got the name right, is not a numerical method, but a software package that implements the FEM.

To compare the radiation patterns, you will first have to simulate both antennas. So, for example, if you compute the currents in both antennas using MOM, you integrate these currents in a manner that calculates your antenna pattern. Do this for both, put them side-by-side, and voila, you are comparing patterns!

The VSWR is easier. You use your numerical technique to calculate the input impedance. In MOM for example, you typically provide a unit amplitude voltage input source. Then when you calculate the current distribution in the antenna, you find the current at the feed point. The input impedance is then Z=V/I. From here, you will need to know the impedance of the circuit feeding the antenna, Zin. This is typically 50 ohms. From there, you calculate your reflection coefficient as

R = (Z - Zin) / (Z - Zin)

So your VSWR is then

VSWR = (1 + |R|) / (1 - |R|)

Do this for both antennas, put your answers side-by-side, and voila, you are comparing VSWR!

-Tip

 

[Aya2002]

plzzzz help me out

hi friend
see this free book you will find these methods was programmed in matlab and ready to use

www.ece.rutgers.edu/~orfanidi/ewa