A technique for designing liquid-tunable RF lenses

In this paper, we apply this technique to a class of MEFSSs with second-order band-pass responses capable of providing a phase shift of 0180° in their pass-band. We show how dynamic phase shift tuning can be obtained. To prove the proposed tuning concept, a waveguide version of a second-order band-pass MEFSS is fabricated and tested at X-band.