Hello!

I'm trying to simulate " Low-Cost Millimeter-Wave Circularly-Polarized Planar Integrated Magneto-Electric Dipole and Its Arrays with Low-Profile Feeding Structures ". The proposed CP ME-dipole element is a PCB-based multilayer structure (see Fig. 1) including two dielectric; substrates made of Taconic TLY-5 and three copper cladding layers, i.e. top layer, middle layer, and bottom layer. A thin pre-preg (with a thickness of 0.1 mm), is adopted as the bonding film to glue the two dielectric substrates. Two L-shaped patch printed in the top layer are rotationally symmetrical with respect to the center of the coupling slot which is etched in the ground, i.e. the middle layer. Two metalized blind vias are utilized for connecting the two L-shaped patches to the ground. A U-shaped narrow micro strip line together with a 50 Ω micro strip line connecting to its center location is used as the feeding structure to excite the proposed CP ME-dipole through the coupling slot. This feeding structure is based on a hybrid substrate consisting of a thin substrate (i.e. Substrate #2) and a thin bonding film. The equivalent dielectric constant of the hybrid substrate is 2.79. The dimensions of the proposed CP ME-dipole element can be found in the caption of Fig. 1

I've simulated this in CST (CST file is attached). My results are similar but nor same. Please check the file "my results" for comparison.

I'm not sure about the design of metallic blind vias, whether i should make holes first and then make copper cylinders or simply inserting copper cylinders. (Screen capture attached)

I've assigned the wave port using Macros>Solver>Port coefficient calculator. I've used the permittivity and height of hybrid substrate which is 2.79 and 0.227mm.

Also, I have selected open add space boundary condition in all directions. But I'm not sure whether this should be different in the wave port direction or not.

Moreover, Impedance is not matched.

Can any one help me what could be the reason for:

1. S11 goes above 10 db. why?

2. How to design the metallic blind vias in CST?

3. What should be the boundary condition in all directions?

4. How can I achieve impedance matching?

5. Is everything OK with wave port assignment?

Any help will be highly appreciated.

Thanks

Sabahat