Microstrip line in HFSS 12

Hello,

I am designing a simple microstrip using two wave ports on its either ends with a ground plane under the substrate. It is NOT an antenna. It is a part of a feed structure - Chebychev three-section transformer. I need to know whether its Characteristic impedance is 155 ohm or not.

Dimensions of microstrip:

Length = 7.9mm
Width = 0.26mm
Thickness = 0.017mm
Material = Copper

Substrate = Rogers RT/duroid 5870 (tm)
Relative permittivity = 2.33

The dimension of ground plane under the substrate:
Length = same as the length of micrsostrip = 7.9mm
Width = 62.3mm (arbitrarily)

Two wave ports on either ends of microstrip with dimensions:
Length = 15 times substrate height
Width = 20 times microstrip width
Both ports are renormalized to 155 ohm

Radiation Boundary = air

I have been told that those wave port dimensions for a microstrip design is a rule of thumb.

With this design simulated in HFSS 12, I am plotting S parameters and Z matrix. I am not getting anywhere near to 155 ohm. Also for S parameter, I am not seeing any dip at a particular frequency where the microstrip is exactly matched to the port impedance (port impedance was set to 155 ohm).

Please provide help. Any help will be highly appreciated. Many thanks in advance.

Attached: Original HFSS 12 file (It takes less than two minutes to simulate it).
JPEG file of the design