Design technique to mitigate unwanted coupling in densely packed radiating elements of an antenna array for electronic devices and wireless communication systems operating in the millimeter-wave band

A feasibility study of an innovative design is presented of a metamaterial inspired antenna array for millimeter-wave band applications where non-mechanical beam-steering is required such as in 5G and 6G communications, automotive and radar systems. In communication systems beam-steering antennas can significantly improve signal-to-noise ratio, spatial directivity, and the efficiency of data transmission. However, in tightly packed arrays the effects of mutual coupling between the radiating elements can severely limit the array’s performance. The proposed antenna array consists of a 3 × 3 matrix of patch radiators that are tightly packed and interconnected to each other. Rows of radiators are demarcated by a horizontal microstrip transmission-line whose ends are short-circuited to the ground-plane. This technique reduces unwanted surface waves that contribute to undesired coupling. Embedded in the square patch radiators is a rhombus shaped slot that increases the effective aperture of the antenna with no impact on the antenna’s size. As the antenna is excited via a single feedline the edge-to-edge spacing between the radiators and the interconnected feedlines are made such that there is phase coherency at the radiating elements. Measured results show that the effectiveness of the proposed array in simultaneously improving its impedance bandwidth and radiation characteristics. The measured peak gain and radiation efficiency are 13.6 dBi and 89.54 %, respectively.