I created a unit cell in CST, and after that I created array from the structure, but my array structures do not behave like the unit cell, a have a DNG material in the unit cell and a SNG in the array.
@ Elijah
Obviously there will be some discrepancy because of the mutual coupling bettween the array elements. But for the single unit cell mutual coupling doesn't exist. This affects the reflection loss.
Did you account for mutual coupling in your design? This is the beauty of periodic structures. In addition, did you ensure that CST is utilizing the correct material parameters or interpolating and using that curve? Interested in your use of double and single negative permittivity & permeability materials. Sounds a bit like directionality control. Would you care to elaborate on your performance goals?
Completely agree with Gebremichael Yohannes Hadgu
In unit cell simulation, the boundary conditions should be correct. It simulates an infinite array. In array simulation, the size is finite. So, some difference will be there in the result. DNG and SNG behaviour depend on the direction of excitation, proper port definition, de-embed distance etc. Please verify the boundary conditions of the unit cell.
Can u send proper boundary condition settings for unit cell and array metamaterial..
Thank you Gebremichael Yohannes Hadgu , William Wallace , Krunal Patel , Aarti Bansal for your answers. The boundary conditions I used are as follows: the ports were positioned at the positive and negative Z-axes, while the boundary conditions for the perfect electric field and perfect magnetic field were set along the X and Y axes
The boundary conditions should be determined by considering the direction of excitation rather than axis. If the incident Electric field is parallel to the side faces of the unit cell then the excitation can not be in the positive and negative z-axis.
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