Compact Dual-Band Endfire Phased Array Antenna for 5G mm-Wave Mobile Terminals

In this article, a compact 28/38 GHz dual-band endfire phased array is presented for 5G millimeter-wave (mm-wave) mobile terminal applications. The unit cell is a planar dipole printed on a single substrate layer. Parasitic strips and etched slots are loadedon the dipole to construct different current paths in 28 GHz and 38 GHz, thus achieving dual-band operation with a single radiator, leading to a small ground clearance of 1.6 mm. A 5-element array with 5-mm element spacing is fabricated. The measured -10 dB impedance bandwidths are 11.7% (26.9–30.2 GHz) and 13.1% (36.5–41.5 GHz) in the two operating bands with isolation higher than 16 dB. The measured peak gains attain 8.5 dBi and 10.4 dBi in the lower and upper bands. The phased array supports a beam scanning angle of –51° to + 50° at 28 GHz and –39° to +37° at 38 GHz.