Wideband Vertically Polarized Endfire Metasurface Antenna Fed by Tightly Coupled Monopole Probe Array

In this paper, we proposed wideband and vertically polarized end-fire two-dimensionally (2D) tapered metasurface (MS) antenna, which is fed by tightly coupled monopole probe array (TCMPA). The TCMPA is a configuration consisting of a top-loaded short vertical monopole within a printed circuit board (PCB) stack between two ground planes. When appropriately designed, it exhibits a wideband characteristic by exploiting the operation principle of the tightly coupled dipole array (TCDA), which is well-suited for thin aperture-sized 5G mmWave antennas. In addition, MS based radiating structure was investigated through dispersion diagram, which is imperative for impedance matching to the thin TCMPA in a PCB stack. Wideband operation of the TCMPA with the MS was demonstrated. Significant advantage of this is that the wideband operation of a very thin end-fire antenna can be achieved using only a PCB: it was shown that the thickness of the proposed array is 0.06 λ _low at the lowest operating frequency. The impedance matching bandwidth of 1×4 array is 22.5–42.1 GHz (60.7 %) for uniform excitation and 24.3–42.1 GHz (53.6 %) for scan angle of 45°. Experimental results, including total active reflection coefficient (TARC), realized array gain, radiation pattern, were compared with simulated results which were in good agreement. Finally, the comparative advantages of the proposed array were demonstrated compared to state-of-the-art 5G end-fire linear array antennas.