about hfss port renormalize

[EdmundZheng]

Dear all

I found that if you renormalize the port impedance to 50ohm, you would get different S11 results though the port impedance was near 50ohm. Can you give me some advice when should I renormalize and what is the reasonable result? Thx in advance!

Regards
Edmund

 

[mtu]

By default, lumped ports are renormalized to a 50 Ohm full port impedance.

 

[YoungEng]

When a waveport is left un-normalized HFSS tries to minimize the reflections between the port and the circuit. This allows you to analyze the return loss of your circuit as if it were feed by a perfectly matched source. If you know the characteristic impedance of the source that will feed your circuit and you wish to see the impact on the RL of your circuit + the mismatch between the source and your circuit then you can use the renormalizing option and set the waveport to a specific Zo.

 

[EdmundZheng]

In communication system, 50ohm charecteristic impedance is usually used, so we must renormalized to 50ohm??

 

[YoungEng]

yes

 

[anthoneo]

Yes you should if you do not want to modify your device further. If you are still designing your antenna for example you can leave it without and then by checking the frequency for minimum return loss, you can go to the impedance vs frequency diagram and find out the attributes your matching setup should possess.---> Re, Im

 

[lostmymind]

Hi guys,

I was wondering about the lumped port renormalization,
in the Lumped Port option, you have to first select an impedance
for the source and then if you wish renormalize...

So my question is what is the point to renormalize lumped port? For example if I have
a impedance source oF 5 Ohms and I don't renormalize, what is the impact
compare to an impedance source of 5 Ohms that I would renormalize to 5 Ohms.

Thanks in advance