metamaterial unit cell simulation with varactor diode

[Kartik Kumar]

Hi

I am simulating reconfigurable unit cell for RIS, I use the below paper for this.

"A varactor-based 1024-element RIS design for mm-waves"

for unit cell I use RLC boundary for varactor diode and periodic boundaries on side walls and floquet port on top and radiation boundary at bottom results match aproximatelly to the paper.

Fow array shown in Fig.11 ansys model, I am using plane wave excitations with different varactor capacitance Is it correct way to calculate array?

What is the corrent excitation for unit cells in array?

[Phan Do]

Hi Karthik,

Now I see you are using Finite Array to expanding unit cell into these 4x4 looking array. Seeing the paper is made of 1024 cells, I'd recommend  simulate this using Floquet port. Unit cell only, coupled lattice pair boundary on four sides, Floquet port on top and bottom of the box. Floquet port excitation will act as plane wave excitation, and you can easily deduct Reflection loss from Floquet port S11. See this sample from our colleague:

https://youtu.be/McfGc7w7Bu4?si=wrcTplaijxvu8aBA

Meanwhile for your current model, there are no port available, and floquet port cannot be contained within unit cell, so cannot directly output reflection loss through S-parameters. If you want to keep the model as finite array of 32x32 with plane wave excitation like in the picture, you will need to manually create two "ports" by creating two non-model sheets above and below finite array, use field calculator to do calculate power through this sheet using poyinting vectors. But depending on the size of radiation space, and there will be also incident wave that creep around the edges of the finite array to be considered, I don't recommend this workflow.

Floquet port which approximates 32x32 to inifinite is a better method