bilateral finline resonator

Dear sir,

i want to use hfss to design bilateral finline resonator in order to get the "Rectangular resonator" curve that represents the relation between " resonator length " and " resonant frequency "

using the following inputs from IEEE paper " The Space Spectral Domain Technique Applied to a Finline Configuration"
a = 7.112 mm, b = 3.5.56 mm, d = 0 . 254 mm,
w/b = 0.1 Єr = 2.22

thanks a lot
mohamed mohy