Low-Profile MM-Wave PIFA Array with Omni-Directional and Full-Coverage Radiations

This manuscript studies the design and radiation characteristics of a new phased array with highly-miniaturized broadband and omnidirectional radiation properties. The procedure of the phased array design is simple and can be easily accomplished on a single-layer substrate material. Its schematic involves eight planar inverted-F antenna (PIFA) resonators with a 1x8 linear arrangement at the edge of the smartphone mainboard having RT5880 material with 1 mm thickness. The PIFA resonators have compact structures with discrete feedings. The introduced array design represents a broad frequency response of 28 to 38 GHz covering multiple candidate bands in the 5G spectrum including 28, 30, 36, and 38 GHz. In addition, the mutual coupling function of the array elements is less than -15 dB. The proposed array appears with a straightforward design procedure, low complexity profile, and its attractive broad impedance bandwidth, omnidirectional radiation mode, and stable characteristics that meet the needs of 5G applications in cellular communications.