Phase representation in HFSS !!

[wiss_int]

Hi folks,
I wanted to calculate the phase of the S-parameter S21 of a very simple hollow waveguide between 12GHz and 18GHz as a function of the waveguide length using HFSS (see attachement).
Normally Phase(S21) = - (2*pi / wavelength) * length.
This is obvious and it can be seen clearly in the graph between 0mm and wavelength/2 = 12.5mm (Frequency here is 12GHz). But the problem is why there is a ripple in the phase! It should actually be linear at least between 0mm and 12.5mm!
P.S: in HFSS -pi < ang_rad < pi.
Thanks a lot!

 

[mohanna]

I have a problem in getting the gain in dbi with frequency of an ultra wide band monopole microstrip antenna, it almost get the gain in -ve db i.e there is no gain of the antenna, i want to ask if the radiation bounadary i define is wrong i define it as a radiation box aruond the microstrip substrate not included the ground, please if any reply to me please send quikly

 

[Rf engineer]

hello wis,


Please tell me the solution of your problem if it has been solved by you.
I need to know the same. I have modeled a circular to linear polarizer converter, and I need to plot the phase shift after the quarterwave plate for 90 degree phase shift........

I also need to plot the axial ratio between the two orthogonal modes.....

can you help me please......


best regards

Sandhu

 

[wiss_int]

Hi,
yes I did find a solution for that. In HFSS it is very important to fix for which mode you would like to get the phase solutions. So when you define your ports, set the integration line for both input and output at the same direction. You will not see any ripple and your phase representation is correct for that mode!

 

[CG0210794]

When you plot the phase use "cang_deg/crad_rad". This should fix your problem.

Cesar