Home / Technical Notes / Electromagnetic analysis / Analysis Condition / Effect of Mesh Size

Effect of Mesh Size

 

The effect of mesh size is studied with the example 4.

 

<Analysis Model>

Example 4: Horn Antenna

 

<Analysis Conditions>

71Ghz (wavelength in the free space: 3.e8[m/s]/71e9[Hz] = 4.225[mm])

 

Adaptive mesh: deselected

 

<Results>

 

2nd-order element

Mesh size	Wavelength/Mesh size	The number of elements	S11[dB]
2.1	2.0	1293	-11.5
1.4	3.0	3924	-29.5
1.2	3.5	6042	-22.8
0.845	5.0	17152	-22.5
0.6	7.0	47498	-22.4

 

 

1st-order element

Mesh size	Wavelength/Mesh size	The number of elements	S11[dB]
1.21	3.5	6042	-10.4
0.845	5.0	17152	-12.8
0.704	6.0	29560	-20.9
0.6	7.0	47498	-22.6
0.4225	10.0	136768	-20.9
0.35	12.1	243077	-21.7

 

S matrix converges with small mesh sizes.

In the case of 2nd-order element, the S matrix is approximately constant for the mesh size of 1.2 (Wavelength/Mesh size = 3.5) or less.

In the case of 1st-order element, the S matrix is approximately constant for the mesh size of 0.6 (Wavelength/Mesh size = 6) or less.

 

Therefore the mesh size needs to be 1/3.5 of the wavelength or less for 2nd-order element, or 1/7 or less for 1st-order element.