not sure about hfss results

Hello guys,

I´m new with HFSS. I´ve done an antenna, and build it physically, so I could compare the results of HFSS with the results of my network analyzer.

The results are not similar. With the network analyzer I can measure the gain in dB at any frequency in a range, and I get a peak around 800MHz but in HFSS I show a far field report, with the gain in dB, and the results are not similar at all.

How can I make a more real simulation? Which factors are affected? I think the key can be here:

1. Air volume around the antenna: I think it should be 1/4 waveleght or more, so for 1GHz it should be 75mm around the antenna.

2. Size of the wave port: I´ve fixed a impedance of 50Ω, but I don´t know if it should have a fixed size. Now, it´s lightly higher than the input pin of the antenna.

3. Number of the wave ports. The antenna has a signal pin and a ground pin, but now there is only one wave port.

Am I doing something wrong? Can anybody help me?

Thanks!!!