Integrated sub-6 GHz and millimeter wave band antenna array modules for 5G smartphone applications

Abstract

Due to their high-frequency ratios, sub-6-GHz and millimeter-wave bands are becoming crucial for fifth-generation (5G) smartphone applications for achieving beam steering and high gain performance without using additional separate antenna elements. This paper presents compact integrated antenna array modules for simultaneous operation in the 3.5 GHz (sub-6 GHz) and (26 GHz) millimeter-wave frequencies. The proposed integrated single antenna element is composed of a microstrip patch antenna, a low-pass filter, and a meandered line-based antenna. The dimensions of the proposed compact integrated antennas are 0.6363 λg×0.2423λg×0.0147λg. The proposed antenna provides wide bandwidth characteristics in both operating frequencies with a -10 dB bandwidth of 500 MHz and 4.5 GHz in the sub-6 GHz and millimeter-wave bands, respectively. The effects of the smartphone on scattering parameters were analyzed. Further, we have studied the safety of smartphone users in terms of specific absorption rate (SAR) and power density (PD). The SAR and PD of the proposed antenna were found under safety limits. Additionally, the proposed antenna array modules were fabricated on a low-cost FR-4 substrate for validation of the simulation results, and a good agreement was found among them. The proposed antenna array packages are excellent candidates for modern 5G smartphones because they provide excellent features such as wide bandwidth characteristics and high gain with wide beam scanning features, and can integrate 3.5 GHz (sub-6 GHz) and (26 GHz) millimeter-wave bands with a high-frequency gap in a small structure.