Hello,
I have a question about an antenna simulation with CST Studio Suite. I have a Bowtie-Antenna, which is fed by a balun and a coaxial cable.
Click image for larger version. 

Name:	Bowtie.jpg 
Views:	12 
Size:	188.7 KB 
ID:	132366

I want to simulate the reflection coefficient of this antenna with CST with a differential feeding. Now my problem is, that I do not know which way of designing the antenna is the right one. I have tried two options:

1. Click image for larger version. 

Name:	Bowtie_1.PNG 
Views:	13 
Size:	16.6 KB 
ID:	132359, Click image for larger version. 

Name:	S11_Bowtie_1_simuliert.PNG 
Views:	10 
Size:	18.7 KB 
ID:	132361
2. Click image for larger version. 

Name:	Bowtie_2.PNG 
Views:	8 
Size:	15.4 KB 
ID:	132362, Click image for larger version. 

Name:	S11_Bowtie_2_simuliert.PNG 
Views:	4 
Size:	17.6 KB 
ID:	132363

On the pictures you can see the different way of differential feeding I tried and the resulting reflection coefficient.
Which one is the right way to simulate the bowtie-Antenna?
The next picture shows the measured reflection coefficient of the real antenna:
Click image for larger version. 

Name:	S11 gemessen.PNG 
Views:	7 
Size:	51.1 KB 
ID:	132364

The reflection coefficient of the first option looks more like the measured results, but I am not sure, whether the design of the antenna is really correct.

Can anyone tell me, which antenna design is the correct one?
Thanks.