HFSS Impedance not Matching Measured

Hello all, I'm hoping someone can clue me in as to why my HFSS simulation results aren't matching my measurements (see attached). I'm simulating a bowtie and SMA connector.

Funny thing is that when I add a parallel 2k ohm resistor and a series 7 ohm resistor, the traces match up a lot more closely. I'm exporting S parameters generated by HFSS and using Spectre to simulate the antenna S parameters plus resistors.

Hope someone can help.

Thanks
Andy

I realize it's hard to answer my prior question without more intimate knowledge about my experiment, so I'll ask another questions....can someone please comment on the accuracy of HFSS's input impedance results? I ask because I was trying to design a dual band high impedance antenna, and HFSS showed great results however the measurements were pretty dismal at the higher frequency. Also, can anyone point out common mistakes that might affect the impedance levels?

Thanks
Andy

Sure. I've found HFSS only gives very accurate port impedances (for waveports - is this what you're using?) when you a) select the correct impedance definition type (i.e. pv, pi, etc. - recommendations can be found in help documentation) and more importantly mesh the port finely.