Multi‐Layer Dielectric Metasurface Antenna With Modal Separation Behavior for Broadband Circular Polarization and High Gain

A multi‐layer dielectric metasurface antenna exploiting the modal separation effect analyzed via characteristic mode analysis (CMA) is proposed. The metasurface is composed of a 3 × 4 array of rectangular patches and is designed on the top of a cardboard box with a thickness of 3.5 mm. Research demonstrates that a set of fundamental modes of the rectangular patch array are separated in the frequency domain. When this separation state reaches an adequate level, a 90‐degree phase difference will be generated between two of these modes. If these two modes are excited simultaneously, due to the 90‐degree phase difference and the wide frequency shift between the two modes, a relatively wide axial ratio bandwidth for circular polarization can be achieved. The radiating element of this antenna is a square patch with chamfered corners. Studies indicate that this radiating element is capable of exciting this set of separated fundamental modes of the metasurface simultaneously. Moreover, the inside of the cardboard box of the metasurface is empty, and the substrate of the radiating element is FR4. This combination of multi‐layer dielectric provides a new attempt to expand the bandwidth and enhance the gain.