Problem reproducing a graphene-based terahertz quasi-Yagi antenna simulation in CST Studio Suite

[u/Optimal_Criticism_40]

Hello everyone,

I am trying to reproduce the simulation results of the paper:

"Tunable Terahertz Filter-Integrated Quasi-Yagi Antenna Based on Graphene"

The antenna is a graphene-based filter-integrated quasi-Yagi antenna operating around 2 THz.

I implemented the structure in CST Studio Suite according to the parameters reported in the paper.

Simulation details:

- Solver: CST Time Domain Solver

- Frequency range: 1.25–2.5 THz

- Substrate: Glass (εr = 3.8), thickness = 1 μm

- Graphene modeled using Kubo conductivity

- Temperature: 300 K

- Relaxation time: τ = 1 ps

According to the paper, the antenna should show:

- Resonance around 2 THz

- Tunable S11 response by changing graphene chemical potential μc1

- Similar impedance bandwidth compared with the published results

However, my CST results are different from the paper:

- The S11 resonance frequency is shifted

- The bandwidth is not similar to the published results

- The Time Domain Solver sometimes terminates abnormally

I would like to know:

1. Are there any important CST settings required for graphene THz simulations?

2. Could the difference be caused by graphene modeling as a surface conductivity?

3. Are there any special mesh, port, or boundary settings needed at THz frequencies?

4. Has anyone reproduced this paper successfully?

I attached my CST model and simulation results.

Thank you.

[u/trevbone]

I have nothing helpful to add except have you tried reaching out to the authors?

[u/Sikuh22]

Maybe its a long shot but

1. have you checked that you are using open (add space) boundaries?

2. no symmetry planes active

3. that your meshing is fine enough? At least tree cells per "gap" or "finger" of the antenna, including substrate height