The highest resonant transmission through an array of holes perforated in metallic screens occurs when the dielectric constant of the substrate, the superstrate and the hole are the same. Changes in the refractive index of the homogenous environment also produce the largest shift in resonances per refractive index unit. In this report, we first propose and apply a technique in realization of free standing bi-periodic array of holes perforated in a silver film. We then show both numerically and experimentally that shifts in (1,0) and (0,1) modes in response to changes in the refractive index of the surrounding dielectric provide a mechanism for realization of a miniaturized tunable quarter waveplate that operates in extraordinary optical transmission mode with a high throughput and a near unity state of circularly polarized light.