Hi Nishita,
There is mesh issues. It is likely related to the way the array is set up.
I see you are inserting several instances of the same component. In finite array, we insert only one instance of the component and then create an array. Check this open example: From file>Open Examples..>HFSS>Antennas>FiniteArray_Radome_77GHz_3D_CADDM. The example comes with a short document. It should help setting up.
Also, before creating the whole array, run the two components separately with proper boundary condition (as isolated elements) and make sure they would run fine with no mesh issues.
You are navigating away from the AIS Discovery experience