Investigation of a Dual-Layer Metasurface-Inspired Fractal Antenna with Dual-Polarized/-Modes for 4G/5G Applications

In this research article, a dual-polarized compact bow-tie-shaped irregular fractal antenna with a dual metasurface (DMS) for directional radiation applications is designed using a dual-mode simple feeding mechanism. A short-circuited strip linked between the impedance transformation feed and the radiating patch activates the induced coupling modes, which are capacitive (C-mode) and inductive (L-mode), respectively. The C-mode antenna operates at 2.39–2.53 GHz, whereas the L-mode antenna operates at 2.88–4.49 GHz. It comprises a DMS positioned at 0.22$\lambda$_∘ from the antenna with 0.016$\lambda$_∘ separation and a 4 × 4 array of checkerboard type hole-injected tiny unit cells on each metasurface. A rectangular cavity-backed slot was employed as the ground plane to emulsify the reflected energy waves from the DMS, in order to start the coupling process with the boresight radiation, resulting in high gain and suppressed backward radiations. The gain in C-mode was 6.74 dBi, and the gain in L-mode was 7.7 dBi. For validation, a miniaturized metasurface antenna with the overall size of 0.32$\lambda$_∘ × 0.32$\lambda$_∘ × 0.22$\lambda$_∘ (where $\lambda$_∘ is the free-space wavelength at 2.45 GHz) was fabricated and measured. The measured outcomes highlight its potential for 4G/5G wireless applications.