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[SOLVED] Find the Input Impedance of Patch Antenna in HFSS

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nothGing

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I have gone through many threads in the forum about finding the input impedance of patch antenna, however all the replies can't catch my mind.

some thread say used Z parameter, but i failed to get it (the zin suppose should be hundreds ohm but i get 20 ohm only)
some thread say used de-embedded way, but how to de-embedded?

So, can anybody tell me the direct way to find the input impedance in the HFSS 13? It's better to teach me in step by step way.

Please don't tell me to use formula, i know it should have a "direct way" to see the input impedance.

Thank you very much
 

Alright guys, I found the way to measure the input impedance of the patch.
 

You can use the Z-Parameter re(Z) and im(Z), these are the impedance of your antenna.
 

The same information can also be achieved through S parameter and S11 in particular for input impedance over you frequency band.
 

mohamed.hagag said:
how plz i need to do it
Click to expand...

Ok. I am using the wave port to excite my patch antenna. If you are using lump port, maybe it can't work out since lump port don't have deembed setting.

First, assign the excitation of the rectangular sheet as waveport.
you will go through this kind of steps.
1) General (name the waveport)
2) Modes (don't change anything, left default)
3) Post Processing (tick on the box "Do not renormalize". At the Deembed setting there, thick the box "deembed", and key in the distance. The distance is your length of feed/micsrotrip line/trace.
4) then, click ok.

after completely running the simulation, right click result (at project tree)
5) create modal solution data report-->rectangular plot-->Z parameter-->magnitude-->create new report.

then, u can plot on the resonance frequency (solution frequency that you need) to measure the impedance of input antenna (impedance at the edge of antenna where connect to the transmission line).

another alternative way is, right click result (at project tree)
5) solution data --> thick on Z matrix --> choose the resonant frequency --> see the 1st positive value at the column Z waveport (this is the impedance of input antenna)

Hope it helps.
 
you can also make use of this relation: S11 = (Zin - Z0)/(Zin + Z0)

Or you can also read the values from a Smith chart. Create a new Smith chart report and insert your S(1,1) trace. If you add a marker to any point on your trace, HFSS should directly display the input impedance for you.
 
Thank you nothGing, but I need your help.. I'm not clear about the "excitation of the rectangular sheet"
If I want to excite a dipole patch, how does the sheet look like?

nothGing said:
Ok. I am using the wave port to excite my patch antenna. If you are using lump port, maybe it can't work out since lump port don't have deembed setting.

First, assign the excitation of the rectangular sheet as waveport.
you will go through this kind of steps.
1) General (name the waveport)
2) Modes (don't change anything, left default)
3) Post Processing (tick on the box "Do not renormalize". At the Deembed setting there, thick the box "deembed", and key in the distance. The distance is your length of feed/micsrotrip line/trace.
4) then, click ok.

after completely running the simulation, right click result (at project tree)
5) create modal solution data report-->rectangular plot-->Z parameter-->magnitude-->create new report.

then, u can plot on the resonance frequency (solution frequency that you need) to measure the impedance of input antenna (impedance at the edge of antenna where connect to the transmission line).

another alternative way is, right click result (at project tree)
5) solution data --> thick on Z matrix --> choose the resonant frequency --> see the 1st positive value at the column Z waveport (this is the impedance of input antenna)

Hope it helps.
Click to expand...
 

aptaua said:
Thank you nothGing, but I need your help.. I'm not clear about the "excitation of the rectangular sheet"
If I want to excite a dipole patch, how does the sheet look like?
Click to expand...

I would suggest using a lumped port. Create a rectangular sheet between the arms of your planar dipole, and then assign a lumped port excitation to it. The excitation line should from one arm of the dipole to the other. An example below:

oCBKX44.png
 
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