I am not getting accurate modes

RF Engineer

Hi! I am trying to simulate square patch antenna with infinite ground plane to calculate modes and modal weighting coefficients but I am not getting accurate results. Modes shown in CST are accurate and FEKO results must match CST and HFSS simulations as per my previous experience. Can anyone please check my design file and spot my mistake?  Simulation file and CST results are in attached file. Thank you so much in advance 

<?xml version="1.0" encoding="UTF-8"?>

 

Johan_Huysamen

Dear RF Engineer

 

In your Feko model you are using the 'Planar Multilayer Substrate' option to model an infinite substrate and ground plane. Could you please confirm that your CST results where also obtained using an infinite substrate/ground implementation?

 

Kind regards,

Johan H

RF Engineer

Altair Forum User said:

Dear RF Engineer

 

In your Feko model you are using the 'Planar Multilayer Substrate' option to model an infinite substrate and ground plane. Could you please confirm that your CST results where also obtained using an infinite substrate/ground implementation?

 

Kind regards,

Johan H

 

Hi! I am sorry for not writing complete details. I can not share my previous model as that work is in review process. In my previous example I carried out CMA of only top layer (a patch antenna without substrate and ground plane) in CST. After that I re-simulated it in FEKO (only top layer), and its results verified my CST simulations. After that I carried out CMA of the same structure with infinite ground plane and substrate in FEKO with probe feed, and its outcome was the same modes (that were found in CST only top layer) but only resonant frequencies were moved to the lower range. Now I am using that procedure to simulate this structure, I am getting accurate modes in CST, because the resonant frequencies and total antenna radiations and currents plotted in HFSS are in closed correspondence with the modes plotted in CST. Now I want to plot Modal weighting coefficients  in FEKO but I am not getting accurate results. 

Can I use finite ground plane and substrate in the design and probe feed to get modal weighting coefficients of the structure? 

Dan Bostwick

I have had the same problem with development of vibration test fixtures.  'Inspire' seems to provide accurate free modes, but restrained modes way off.