where am i doing wrong? (CST antenna model)

hi;
im going to remodel the referance antenna in the paper named "Printed Double-T Monopole Antenna for 2.4/5.2 GHz Dual-Band WLAN Operations" (IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 51, NO. 9, SEPTEMBER 2003).
the antenna has only one resonant frequency between 2130-2535MHz, but in my CST simulation it has 4 resonant points. and also i remodelled it by using HFSS. it has one resonant but it has a frequency shift.
im uploading the paper and my simulation files.
please could you look at it?
where am i doing wrong.
thanks for your helps.

hi!
you have wrong waveport definition both in CST and HFSS. I used a lumped port in CST (Take a look at the attachment).
Please try to find documents how to define waveports (seach in edaboard, there are a lot).

thanks for your help

hi shameemkabir;
how can i know, which port must i use?
when i looked the antenna design example in cst, waveport is used in it.

You can use both ports in this case. As a first simulation you try with lumped port (if you want only one mode). If the result is satisfactory, you draw the waveguide port. However, it is always better to use waveguide port, since it also shows you the field at the port. You should get very close results for both.