Exploiting mechanical flexure to design tunable periodic structures

We present novel approaches for designing periodic structures with tunable frequency responses. The proposed techniques exploit mechanical deformations and do not rely on using any electronically tunable devices to achieve tunability. Overlapping, stretching, and flexure are the three main mechanical means of tuning studied in this work. All of these techniques can be used to tune the capacitance and/or inductance of suitably-designed sub-wavelength periodic structures. The concepts introduced in this work are experimentally demonstrated by designing and fabricating a mechanically-tunable miniaturized-element frequency selective surface (MEFSS). The MEFSS is fabricated on an accordion-like substrate that can be contracted or stretched to change its frequency of operation. The response and tuning properties of this structure are experimentally characterized using a free-space measurement system. Experimental demonstrations confirm the viability of using mechanical flexure to tune the responses of such sub-wavelength periodic structures.