Help for Smith V3.10 - Fritz Dellsperger
Help for Smith V3.10 - Fritz Dellsperger
Help for Smith V3.10 - Fritz Dellsperger
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Remark on relative permittivity (relative dielectric constant) � r using lines:<br />
If the line consist of microstrip, stripline or other planar line, use effective relative permittivity � re .<br />
� re is a function of substrate � r , W/h, t and frequency.<br />
For microstrip lines it can be approximated by<br />
t �0 f �0<br />
�0.555<br />
�r �1 �r<br />
�1�<br />
h �<br />
�re<br />
� � 1 10<br />
2 2<br />
� �<br />
w<br />
�<br />
� �<br />
w/ h�<br />
1<br />
Sometime instead of � r the relative velocity v r is used.<br />
v r is related to � r by<br />
1<br />
v �<br />
r<br />
�<br />
r<br />
18
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