How to setup E field and H field in cst

can anyone help me how to setup E field & H field in CST software? How can we know which TE and TM mode are suitable for reflectarray antenna?plz help me..

In the navigation tree of CST they have what they call field monitors same as in HFSS. Right click on this and choose E-field H field etc. Then on your 2D/3D results you may obtain the results.
Also for reflector antennas the mode of propagation is the principal TEM mode since these are unguided space waves as far as I am concerned.
Unless you are referring to the mode of a waveguide feeder for instance, in this case the most common is TE10, for a rectangular waveguide feeder. You can claculate the right mode by determining cutoff frequencies for the mode you desire at the frequency of operation.
Refer to Clarke R H, Brown J. Diffraction Theory and Antennas. John Wiley and Sons, Jan
1980.

thank a lot gamba007..
thanks for respond,, can u tell me which mode are better?TE or TM?i dont have the book that you recommend for me..btw thank you very much,,