Transmission mode tunable impedance surface

Does enybody know any possible configurations for transmission tunable impedance surfaces? I mean, in principle it should be working like Sievenpiper's reflection impedance surface, with varactor diodes for controlling the output beam direction by controlling the phase distribution along the surface, but in the transmitting mode. So, a plane wave impinging to the surface normally must be transmitted towards the output of the system (beyond the active surface) with a non-normal beam direction depending on the phase along the structure, controlled by varactors' capacitances. I tried to simulate an array of vertical metal strips in HFSS with an RLC condition (variable capacitance) between adjacent strips disposed on the surface which is impinged by the input plane wave. As the capacitance increases, the transmission coefficient between input and output gets decreasing. I should mantain a pretty high transmission coefficient when varying the phase distribution. But with this structure I can't manage to do it. I attached a sample file for the unit cell. Any directions or help to design a similar structure for obtaining the desired behavior?

Thanks.

I.