DrunkBear
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cst calculate impedance
This question puzzled me for a long time and i post it here since i noticed another similar problem on impedance is discussed these days.
As we know the input impedance is an extremely important parameter to antenna design.But can we check this parameter directly in CST?
In 2D result, there are two items called "wave impedance" and "line impedance" respectively. I examined the help file which gives the definition to them.
The wave impedance is defined as the average ratio of the transversal electric field to the transversal magnetic field for all grid points. But i don't find any importance of this because i've not found any book on electromagnetic theory or microwave engineering which gives definition to the "wave impedance" in this way.
The line impedance is defined as the ratio of of the power to the squre of total current in the port. According to my understanding, for TEM or QTEM modes, it is the input impedance at the port since Z=P/(I*I)==>Z=U/I. I'm not sure whether it is correct.But when i examined the example of the "rectangular patch antenna" that CST itself provides, i noticed the "line impedance" is almost exactly equal to the characteristic impedance of the microstrip feedline, which means the impedance of the patch is not considered if the patch is treated as a terminal load of the transmission line!
what are your comments? Thank you!
This question puzzled me for a long time and i post it here since i noticed another similar problem on impedance is discussed these days.
As we know the input impedance is an extremely important parameter to antenna design.But can we check this parameter directly in CST?
In 2D result, there are two items called "wave impedance" and "line impedance" respectively. I examined the help file which gives the definition to them.
The wave impedance is defined as the average ratio of the transversal electric field to the transversal magnetic field for all grid points. But i don't find any importance of this because i've not found any book on electromagnetic theory or microwave engineering which gives definition to the "wave impedance" in this way.
The line impedance is defined as the ratio of of the power to the squre of total current in the port. According to my understanding, for TEM or QTEM modes, it is the input impedance at the port since Z=P/(I*I)==>Z=U/I. I'm not sure whether it is correct.But when i examined the example of the "rectangular patch antenna" that CST itself provides, i noticed the "line impedance" is almost exactly equal to the characteristic impedance of the microstrip feedline, which means the impedance of the patch is not considered if the patch is treated as a terminal load of the transmission line!
what are your comments? Thank you!