I am trying to design a hexaband PIFA [Ref:- Do-Gu Kang and Y. SUng, "Compact Hexaband PIFA Antenna for Mobile Handset Applications" IEEE Antennas and Wireless Hexaband Letters, Vol. 9, 2010]. However, I am facing the following problems:
1. When I modelled SMA connector perpendicular to the plane of antenna, the return loss performance was not good. However, I was getting the required resonant frequency.
2. When I modelled SMA coonector, parallel to the plane of antenna as seen in the attachment, by changing various parameter the RL performance could be corrected but obtaining required resonant frequency was not possible.
3. I tried assigning lumped port, but even that was giving me error.
Please help me to provide feeding to this antenna.