Circular Conformal Array Antenna With Omnidirectional and Beamsteering Capabilities for 5G Communications in the 3.5-GHz Range [Wireless Corner]

Abstract

A circular conformal array antenna (CAA) with beamsteering capabilities as well as omnidirectional performance at 3.5 GHz (S-band) is presented. The single radiating elements are formed by double-stacked microstrip patches placed on the planar faces of an octagonal holding structure fabricated with a 3D printer. An eight-way tunable feeding network (TFN) is designed, manufactured, and integrated into the conformal structure to excite the array elements. Novel tunable T-junctions (TTs) based on p-i-n diodes are proposed to form the TFN in microstrip technology. This novel T-junction allows a splitting configuration with uniform distribution to the two output ports or a switching mode to deliver the signal to either output port. In all T-junction operation modes, good input matching performance is achieved. The TFN network is integrated into the conformal antenna and digitally controlled by a microcontroller Arduino MEGA. A total of 29 states grouped in six modes with a global matching bandwidth of 17.2% can be selected. The omnidirectional radiation and beamsteered directional patterns (covering 360°) can be electronically tuned. The proposed antenna is suitable for future 5G terrestrial communications in the 3.5-GHz International Mobile Telecommunication (IMT) range, the primary candidate band for the first 5G networks.