Active beam-steering millimetre-wave antenna array system for 5G and beyond

<p dir="ltr">This research focuses on the design and development of a smart beam-steering antenna system offering wide bandwidth, high gain, wide beam-steer, and easy implementation within a small form-factor at 26 – 30 GHz for application in 5G base?stations and beyond. This thesis explores dielectric filled waveguides (DFW) and substrate integrated waveguides (SIW) slot array antennas chosen for their frequency?-controlled beam-scanning nature. A switched DFW antenna array system offering a 60º beam-steer at fixed frequency has been realised.</p><p dir="ltr">Corrugations have been investigated as a replacement for vias in an SIW to create a corrugated substrate integrated waveguide (CSIW). This research introduces a novel integrated-digitated capacitor based CSIW (IDC-CSIW) offering much lower transmission losses than conventional CSIWs. A novel method to calculate the cut-off frequency for CSIWs and a design methodology has been presented that can be scaled in frequency. Active PIN diodes have been included within the corrugations to offer a new method to manipulate surface current and electric field distribution within selected regions of the IDC-CSIW and demonstrate a wide beam-steering characteristic. An IDC-CSIW based slot-array antenna has been presented to offer 120º beam-steering in the azimuth plane and ±15º beam-steer in the elevation plane with an approximately constant gain of 13 dBi.</p><p dir="ltr">Dielectric lenses are known to be a suitable add-on for antennas to produce highly directive beams. However, a gap has been identified in the state-of-the-art dielectric lenses. When used with travelling wave antennas (TWA), conventional dielectric lenses tend to be less effective when compared with their performance with a standing wave antenna (SWA). Radiating elements in a TWA are fed with phase shift and reduced amplitude, which has been hypothesised to affect the performance of the lens. A new design methodology for lenses with TWAs has been developed and the new logarithmic shape dielectric lenses have been measured. Finally, a full 360º beam-steering layout in the azimuth plane with 30º steer in the elevation plane has been demonstrated with six of the proposed IDC-CSIW slot array antennas paired with the proposed bespoke lenses, demonstrating their suitability for 5G base-station applications.</p>