What is slow-wave factor? and how to extract it?

I am green in slow-wave, photonic bandgap...
And I am trying to understand more about slow-wave factor.
I read many papers that shows constant phase normalized by k0 (B/k0) or lambda0/lambda
how compare slow-wave factor of conventional microstrip and pbg or dgs microstrip?

I am not sure about how to calculate it.

thanks in advance

regards

I got something about,

slow-wave factor is a quantity proportional to the inverse of the phase velocity. In math swf=beta/k0 , beta=k0*sqrt(Eeff), so beta/k0=sqrt(Eeff).

I have .s2p results, but I dont know how to plot this equation by s-parameters.
Plz Help me.

Thkz in advance

Hi Logan_

http://www.athena-em.gatech.edu/memb.../2898_ref4.pdf
http://cat.inist.fr/?aModele=afficheN&cpsidt=13811913

Pl