CST Simulation not matching network analyzer

I created a dipole antenna in CST and built it by hand using componants in my lab. The problem is that when I use the network analyzer to measure the impedance and VSWR, the results are not the same as the simulation.

I can create a matching circuit using ADS or change the measurements of the length/width of the dipole, but I feel that this should not happen.

For example, If I were to make this antenna in bulk quantities, they all should work very similiar to the simulation. I shouldn't have to adjust each dipole individually.

This has happened to a number of different kinds of antennas I began to build to gain experience in the field
Does this usually happen in Antenna Engineering?
What can I be doing wrong and how can I get better at building antennas I simulate in CST?

My guess is that you didnt fabricate the antenna the same way you simulated it. You are most likely measuring the VSWR from your SMA or N connector to the dipole. When you cut a hole in the ground plane, it's important that you fill it with a dielectric, or size the hole to account for air as the medium in that section of your transmission line from the network analyzer to free space.

**broken link removed**
I hope this helps.

I wonder how you connected the dipole to the single ended VNA port? You'll need a balun, or at least effective isolation of the cable effect. VNA calibration to the right reference plane is presumed.

Get some ideas from previous threads like this https://www.edaboard.com/threads/273612/

FvM said:

I wonder how you connected the dipole to the single ended VNA port? You'll need a balun, or at least effective isolation of the cable effect.

Click to expand...

Yes, absolutely! Otherwise the cable become part of the radiating structure (different from simulation!) and results change when you touch the coax shield.