A Compact Multi Antenna Design with High Isolation in 5G Full Screen Mobile Phone

A compact three antenna design scheme with high isolation is proposed. These three adjacent antennas are located at the bottom of mobile phone, with total size of 75.0mm by 32.0mm, the bottom clearance and side clearance of the mobile phone are 3.5mm and 1.3mm respectively. Seen from the back of mobile phone, antenna 1 (A1), antenna 2 (A2) and antenna 3 (A3) are arranged in order from left to right. These three antennas adopt injection molding process, and each antenna is radiated by metal frame and laser direct structuring (LDS). The antenna type of A1, A2 and A3 is inverted F antenna (IFA) and parasitic antenna, loop and parasitic antenna, IFA respectively. All three antennas support middle band and high band, while frequency range of middle band and high band are 1.71GHz–2.2GHz, 2.3GHz–2.69GHz respectively. The measured results show that, the passive efficiency in free space of A1, A2 and A3 are −5.5dB, −5.1dB and −5.1dB respectively. Compared with free space, there are at least one or two antennas whose attenuation are less than 4dB in the mode of head and hand. Two wide common ground design is applied to improve three antennas' isolation, corresponding isolation are −10dB, −15dB and −21dB. As A2 is the transmitting antenna, the measured SAR values of A2 are within the safety range specified by Federal Communications Commission (FCC). A 5G mobile phone equipped with these three antenna has been mass produced and shipped.