Impedance Matching Enhancement of A Microstrip Antenna Array Designed for Ka-band 5G Applications

This paper presents an impedance matching enhancement of a 1 × 4 rectangular microstrip antenna array designed for 5G applications in Ka-band. An efficiency comparative study between different impedance matching techniques, such as quarter-wave transformer, open-circuited or short-circuited length of transmission line (a stub) and smooth shapes tailored in the low corners of each antenna is presented. Indeed, an excellent input reflection coefficient $S_{11}$ value of −75 dB at 28 GHz and a bandwidth of 8.3% are achieved. In addition, radiation characteristics show a significant gain of 13 dB in E-plane. Due to its simple low-profile planar structure, which is easy to fabricate with no intricate process embroiled, and its attractive radiation characteristics, this planar antenna array meet the needs of 5G applications in Ka-band.