Antenna Setup in different configuration

Hello,

I am trying a 2 cases setup like this where there will be 2 horn antenna facing each other and S parameter data will be extracted.

For the 2nd case using the similar setup there will be a large metal plate in the middle of the line of sight of horn antenna. I should expect antenna with metal plate, the S parameter value should be very different as metal plate will block almost everything to propagate from antenna 1 to antenna 2 or vice versa.
Horn_Ant_1.zip
However, I am getting similar response for both cases. Is there any design issues that I am missing?

Is the plate is thin and floating?

Yes plate is thin and has been kept at the middle of two antennas.

Yes, s21 and s12 should be considerably different, most frequencies blocked with some resonances.

You have placed a solid sheet at 42.5cm from each horn antenna. This is in the far field of the antennas, horn antennas which have the low cut-off at about 6.7GHz (lamda = 4.4cm).
To see a difference in S21, use instead of the undefined solid sheet, a solid copper plate with some thickness.
The plate dimensions should be bigger than the distance of 42.5cm.
Also you can place the copper plate not in the middle, but closer to one of the horn antennas.

This is not anisotropic setup, so why should S12 and S21 will be different? What metal plate should do to block transmitted signal from both antenna with respect to free space transmission.



Thanks. Understood. But why the thickness should be important, practically a thin metal is enough to block S12 and S21 from antennas. In my opinion thickness should not be very important because all we need to care about skindepth and GHz range which is very low. What I did in Ansys to define this metal as IE region and assign some finite conductivity. It worked.

What do you mean thin metal? Your undefined solid sheet doesn't have ANY thickness.
You need a real material with some thickness to be able to see changes in transmissions of radiowaves. Or to define the sheet with finite conductivity (how you mentioned above), but this is a kind of theoretical behavior and not real life one.

I define sheet with finite conductivity and assign IE region for that.

I think your sheet does not cover the whole main lobe of your antenna pattern. It may sound cheeky but try using a bigger plate with thickness enough to attenuate it enough.

And are you doing this in an anechoic chamber?

Thanks @ktr
Yes, for practical measurement, I am using anechoic chamber and I am trying to simulate the same setup in HFSS as well.

Unless the plate is low impedance grounded, it will appear transparent

That's interesting. But how to design that overall system in HFSS?