Wideband and Wide Beam Scanning Dual-Polarized Phased Array Antenna-in-Package Design for 5G Applications

Millimeter (mmWave) 5G phased arrays require multiple simultaneous features for reliable high data-rate communication. However, it is challenging to simultaneously achieve a true wideband operation for all parameters due to mutual coupling and grating lobe issues. A
$5\times5$
-stacked patch rectangular phased array was designed and fabricated in a 15-layer low-temperature co-firing ceramic (LTCC) substrate. This work utilized multiple design strategies, such as employing stacked patch topology, electromagnetic band gap (EBG) structures, and the rotation of elements to obtain a true wideband performance. The single element of the phased array was a dual linear polarized stacked patch antenna with notched corners. Compared to a standard patch antenna, the bandwidth was enhanced by 15.3%. The undesired mutual coupling between elements was minimized by rotating nearby elements and introducing EBG structures between the adjacent elements. A wideband beamforming network composed of a Rotman lens and a 5-way Wilkinson power divider (WPD) was also designed and fabricated. The proposed phased array achieved 6 GHz of bandwidth, covering 24 to 30 GHz and achieving a maximum gain of 17.5 dBi and a wide beam-scanning range from–50 to +50 degrees. This work also introduced a figure of merit (FoM) based on all critical performance parameters for objective comparison with state-of-the-art designs. The proposed design achieved the highest FoM (0.451), whereas most similar 5G phased array designs achieved much lower FoM value.