Novel Design of X-Shaped Slot Antenna Backed by a Flat Reflector for 5G Sub-6 GHz Band

In this paper, a novel design of X-shaped slot antenna, whose input impedance is approximately to dipole slot antenna, is proposed for use in the private 5G of Sub-6 GHz band. The proposed X-shaped slot antenna is truncated from the infinite shape of self-complementary antenna. The proposed X-shaped slot antenna has the input impedance around $50~\Omega $ to $60~\Omega $ and has wideband and high gain characteristics, which is the crucial contribution of the design for planar array configuration. The X-shaped slot antenna is connected to a $50~\Omega $ input port through microstrip line which is electromagnetically coupled to the center portion of the X-shaped slot antenna and terminated by an opened circuit line. In this paper, antenna characteristics are simulated by using Finite Element Method (FEM) in commercial simulation software EMPro (Keysight). From simulation results, the X-shaped slot antenna has magnitude of reflection coefficient |S $_{11}\vert $ less than −9.7 dB (VSWR <2) within the frequency range of 3.15 GHz to 5.1 GHz which is about 1.95 GHz (47.2 %) impedance bandwidth. The simulated maximum gain of X-shaped slot antenna is around 11.1 dBi. To validate the simulation results, the prototype of X-shaped slot antenna has been fabricated and the antenna characteristics have been measured. From the comparison between simulated and measured results, the proposed X-shaped slot antenna is applicable for the private 5G in Sub-6 GHz frequency band.