Analyse it as a periodic structure to get the dispersion diagram. I suppose you could also excite the whole structure at different frequencies and measure the wavelength on the structure at each frequency and then plot frequency against wavenumber, but you won't get a periodic dispersion diagram.

Malcolm White thanks a lot. Then how to excite it? I strip should be scited from the right and left. But, when analyzing it as a periodic structure, it is excited from the top and bottom. I have no idea how to relate the result of the two simulations.

Malcolm White is correct, you need to simulate only a unit cell first. Just take one stub with excitation from left to right or other way round. Use two ports, you can calculate alpha and beta parameters in terms of s-parameters and then you can plot the dispersion curve.

Nitin Kumar Yes, I understood it, thanks. So I got two questions now. What to set the boundaries, especially the top and bottom ones?

2- How to find the dispersion curve through the S-parameters (any reference, link etc)?

Yousef Vahabzadeh for first question make it radiation boundary along with other faces of the radiation box.

second part:

A CRLH leaky wave antenna on SIW with continuous scan using novel S-slots,

this is my paper only and there is another paper similar to this.

I hope you will find it useful

Thanks

Nitin Kumar . I don't think the link to your paper pasted into your reply properly.

http://www.tandfonline.com/eprint/J7YaSa5J4qjM4hpIy2SS/full

this will work

Nitin Kumar Thanks a lot

Yousef Vahabzadeh

Nitin Kumar

Dear Yousef

Did you manage to plot the dispersion diagram using the formula from the paper proposed by Nitin Kumar?

https://www.researchgate.net/deref/http%3A%2F%2Fwww.tandfonline.com%2Feprint%2FJ7YaSa5J4qjM4hpIy2SS%2Ffull

If yes, please could you tell me the values you took for Zo1 and Zo2 ?

Also, |S11| and |S21| are just the magnitude? if yes where does the imaginary part comes from? Since gamma = alpha +j*beta.