Low-profile bandwidth and E-plane radiation pattern reconfigurable patch antenna for sub-6 GHz 5G applications

Abstract

In this work, a low-profile bandwidth and E-plane radiation pattern reconfigurable microstrip antenna is presented for the fifth generation (5G) sub-6 GHz, 3.3 to 4.2 GHz band. The proposed antenna is miniaturized using a partial ground plane technique. The bandwidth and the pattern reconfigurability are realized using a reconfigurable second element feed line and an additional λ/8 connecting stub of a 2-element circular patch array. The additional λ/8 connecting stub transforms a conventional series RLC into a parallel RLC combination leading to larger bandwidth. The working principle and the design process of each iteration have been detailed. The working principle is validated using the surface current distributions in different modes and developing and testing a prototype. The proposed antenna structure has two operating modes covering from 3.28 to 4.34 GHz band; (I) measured 19.4% fractional bandwidth, unidirectional E-plane pattern and (II) 27.4% fractional bandwidth, bidirectional E-plane pattern. The measured centre frequency of both operating modes is 3.5 GHz, and 3.79 GHz with continuous coverage of the 5G band. The measured H-plane radiation pattern of the antenna is identical in both operating modes.