A Broadband CP Square Slot Antenna Array for Future 5G Communication Systems

This paper presents a broadband circularly polar-ized (CP) antenna array for millimeter-wave (mmWave) applications. The overall size of the
$1 \times 4$
antenna array is
$28\times 23\text{mm}^{2}$
and covers the 28 GHz to 38 GHz bands. Each element of the antenna array consists of a wide square slot (WSS) with a T-shaped stub extended in the ground plane. The impedance matching and the CP bandwidth is improved by introducing asymmetric fractals in the ground plane. The antenna array elements are fed by a simple 4-way power divider network. The simulated and measured impedance bandwidth of the array is 49% (26.6 GHz to 42.9 GHz) and 49% (26.6 GHz to 42.4 GHz) respectively. The simulated and measured 3dB axial ratio (AR) bandwidth is 29.5% (34 GHz to 44 GHz) and 28.5% (35 GHz to 42GHz) respectively. The peak gain of 8.5-11.2 dBi is measured throughout the bandwidth. The proposed antenna array is suitable for commercial use in future 5G communication systems.