Gain and Bandwidth Enhancement of Ferrite-Loaded CBS Antenna Using Material Shaping and Positioning

Loading a cavity-backed slot (CBS) antenna with ferrite material and applying a biasing static magnetic field can be used to control its resonant frequency. Such a mechanism results in a frequency-reconfigurable antenna. However, placing a lossy ferrite material inside the cavity reduces the gain and impacts the impedance bandwidth. This letter develops guidelines, based on a nonuniform applied magnetic field and nonuniform magnetic field internal to the ferrite specimen, for the design of ferrite-loaded CBS that enhance its gain and tunable bandwidth by shaping the ferrite specimen and judiciously locating it within the cavity. To validate the modeling, simulations were performed using ANSYS's Maxwell 3D and HFSS, and they were compared to measurements conducted in the Arizona State University (ASU) anechoic chamber.