| dc.description.abstract | Frequency selective surfaces (FSSs) are periodic structures which perform a spatial filtering operation, such as band-pass, band-stop, etc. in application of multiband reflector antennas, radomes, absorbers and so on. The filtering is normally achieved by periodic arrangement of metallic shapes or slots on a dielectric slab. The responses of the FSS are impacted by the unit cell structure, type of the element, material properties and arrangement of the array. The interest in frequency agile and wideband systems has led to an expanding design space to include reconfigurable FSSs. Reconfigurable FSSs have the advantages of wider range of operating frequencies, compensation for fabrication errors by tuning mechanically. The reconfiguration could be achieved by solid-state devices (varactors, PIN diodes), usage of semiconductors, changing the substrates’ characteristics or the dimensions of the elements. Tunable FSS are in practical need for applications such as tunable radomes and adaptive screening of unwanted wireless transmissions. For a continuous tuning over the frequency range, fluidic tuning and mechanical reconfigurable FSSs claim to deliver the most dramatic continuous parameter variations.
In this work, a 3-D mechanically tunable FSS has been presented with a band-stop characteristic. The 3-D FSSs has displayed greater flexibility and controllability compared to conventional 2D FSSs. They have the ability of setting the resonant frequency and continuous tuning the operational filter states with a change in length or height of the resonator, offering the tuning and switching functionality from the same structure without the use of additional electrical components. In this design, the reconfiguration is achieved by compressing the FSS structure, varying the height and the element shapes. Simulations and measurements of a FSS prototype manufactured by 3-D printer, some metallic and dielectric components are provided to demonstrate the tuning capability in S-band. A 490 MHz tuning range could be achieved by this design, while adding some dielectric material inside, a wider tuning range of 600 MHz could be reached. The measurement results show a good match with the design by HFSS. | en |
