Comparative study of miniaturized microstrip antennas designed with different super-substrate materials operating at 900 MHz

Different microwave super-substrate materials are comparatively studied to fill into microstrip antennas (MSAs) operating in the ultra-high-frequency (UHF) band at 900 MHz. These super-substrate materials include a cubic high permittivity dielectric, multilayered extremely high permittivity dielectrics, and new spiral metamaterials (SMMs). They are all demonstrated equivalent to shrink the MSAs which are comprehensively investigated in full wave simulations. In addition to the electric performances, the mechanical weight and material feasibility for the super-substrate materials are also compared. In a balanced consideration of all of electric, mechanic and material properties, the new SMM super-substrate is shown to be the most promising one among the three, which is particularly useful to design a miniaturized MSA in the UHF band.