hello everyone
i designed an antenna and also a EBG structure to improve its behavior in both CST and HFSS but i'm not sure what kind of boundary i should use to get reasonable results. i try many things but still i don't get any good result.
for example in CST i get this message:
The topology of port 1 has changed after adaptive port meshing. This could influence the 3D simulation as well as the port modes.
or Maximum simulation time reached ...
i didn't do anything with mesh...
and well s11 is very bad, antenna alone is much better. can anyone help me about this? i read CST Help and also HFSS Help but couldn't find anything good ...
thank you
@ Irfan Mujahidin ok thank you but i don't understand, i don't think your answer is relevant to my question. i know the size of EBG and everything, i wanna know if there is any specific boundary and excitation for it.
Hello,
Yes, there is boundary condition, which is required to simulate. Periodic boundary can be used.
Thanks,
Thanks a lot Smrity Dwivedi and Nasr Alkhafaji
. I really appreciate your help.
Hello, if you have used EBG structure under your antenna and the antenna is bidirectional, some of backward radiation will reflect into the input port and decreases the absolute magnitude of S11 which leads to bandwidth loss, this means you should trade-off between front -to-back Ratio and bandwidth improvement. As I have seen in these situations, a spacing between antenna and the EBG surface can help the bandwidth. But, usually when the antenna is surrounded by EBG structure, the bandwidth increases (and also the absolute magnitude of S11) due to surface wave reduction.
I hope these might help you.
Article An Overview of Electromagnetic Band-Gap Integrated Wearable Antennas
https://ieeexplore.ieee.org/document/7868133
https://www.researchgate.net/post/Waveguide_port_position_and_boundaries_condition_in_CST
https://www.youtube.com/watch?v=8bqFOxHgQws
Article Pixelated Checkerboard Metasurface for Ultra-Wideband Radar ...
Syed Ahson Ali Shah thank you for all the recommendations. i'm gonna read them all. thanks.
Hossein Vahimian thank you for your explanations. yes the EBG structure is under the antenna and based on the paper, i used a layer of foam between antenna and EBG, with thickness of 1 mm. i dont know which part i'd missed. but i'm working on it.
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