HFSS port for Loop and "port Only "solver

[panto]

hfss ports only

hi I am very new to using Ansoft HFSS and this is my first post and I need your help:
my project is a circular loop antenna over a substrate without ground plane so the signal must be taken in differential mode.

I choose a waveport but I don't know the exact dimensions of the waveport so I decide to use "port only" solver to check if my dimensions were set correctly a t 1.6 Ghz.I fixed the reference impedance of the port to 50 Ohm and I wanted to obtain from simulation a Zo near to 50 Ohm.When simulation finished I selected HFSS/Results/Create Report/Terminal Solution Data,Rectangular Plot/Terminal Port Zo but I obtained 0.0056 Ohm clearly there's something wrong

my waveport is set correctly for this kind of simulation? and the terminal line? the processofor obtaining the results from port only solver is correct? and which are the correct dimensions?

I add some imagines of my project.
any advide or commenti is appreciated
Thanks very much

 

[panto]

nobody can help me?:|

 

[emadi]

please attach your .hfss file.

 

[panto]

here is my hfss file.

In this file I used a lumped port and characteristic impedence resulted 46 Ohm so close to 50.
my problem continue,instead, with waveport I can't get the 50 Ohm impedence with port solver even changing more and more time the dimensions of the port

thanks

 

[loucy]

Your "lumped port" is inappropriate. You should draw a rectangle that fits exactly in the gap of the loop so that the antenna+the rectangle (over which the lumped port will be defined) forms a complete loop.

To define a waveport for this problem, think of a way to excite the antenna through some transmission line. (The wave shall be guided by the tranmission line into the antenna, as the wave at the waveport is assoicated with some transmission line mode.) It could be a coaxial line (not a differential feed though) or two parallel straight strips printed on the substrate...... In the latter case, do expect the wave impedance to be exactly 50ohm. Your waveport should be defined at the beginning of the coxial line or the parallel strips, because the other end would be in contact with the antenna.