16-element CPW Series Fed Millimeter-wave Hexagonal Array Antenna for 5G Femtocell Applications

Abstract

A 16-element coplanar waveguide series fed hexagonal array antenna is proposed at millimeter-wave frequency range. In this paper, the analysis is initiated from a single-element hexagonal patch then extended to 1×2 array, 1×4 array, and 4×4 series fed hexagonal patch array antennas. The idea behind this design is to improve fractional bandwidth stage-wise with improved gain maintaining constant efficiency with all the structures. The 16-element array antenna is fabricated on Rogers RT Duriod 5880™ substrate with ɛ r = 2.2 and 0.508 mm thickness. This array antenna exhibits low return loss at 28 GHz with a reflection coefficient value of −31.02 dB including almost 102% radiation efficiency and attained a maximum gain value of 8.98 dBi. The results are quite comparable with simulated 4×4 array antenna using the HFSS tool. The size of the proposed antenna is quite small which will be best suited for 5 G Femtobase stations to provide indoor communications at millimeter-wave frequencies.