Mechanically Frequency Reconfigurable Cavity-Backed Slot Antenna based on ENZ Medium for Millimeter Waves

This work proposes a mechanical frequency reconfigurable waveguide-fed cavity-backed slot antenna based on ENZ medium for millimeter wave operation. The antenna air-filled metallic cavity is doped by FR4 dielectric slabs enclosed by four metallic rods to achieve an ENZ medium and fed by a commercial single waveguide-to-coaxial transition through a standard WR28 waveguide. The cavity is semi-cylindrical, providing a semi-omnidirectional radiation pattern at the H-plane. An external sleeve mechanically actuated allows reconfiguring the antenna bandwidth using different slot lengths. The antenna full-wave numerical analyses show reconfigurability from 24.41 to 26.88 GHz, with a gain ranging from 4.80 to 5.15 dBi for eight different slot lengths.