Millimetre-waves Antenna Arrays for 5G and Wireless Power Transfer

Millimetre-wave (mmW) technology is one of the promising candidate for the deployment of next generation wireless communications. Key benefits of mmW is the availability of large continuous bandwidth and miniaturization of microwave components due to short wavelength. Despite of aforementioned benefits of mmW technology there are also some challenges such as the high path loss, severe attenuation due to atmospheric absorption and signal blockage. One solution to mitigate the path loss and signal blockage at mmW frequencies is by using high gain directional antenna arrays with beam steering capabilities for point-to-point communication. The goal of this thesis is to develop new modelling techniques and fabrication methods for the design and implementation of efficient, cost-effective, high gain, easy to design and manufacture mmW antenna arrays and other microwave components (integrated waveguides, phase shifters and rectifiers) for 5G wireless communications and far field wireless power transfer (WPT) applications.
A simple yet efficient excitation technique for microstrip patch antenna (MPA) arrays is presented based on higher order mode substrate integrated waveguide (SIW). The proposed approach also enhances the gain of antenna array due to less radiation and transmission losses. In addition to the above, a low cost and easy to manufacture integrated lens antenna (ILA) based on low infill density 3D printing technology is presented for applications where higher gain is required while retaining the small foot print. Proposed antenna arrays are well suited for millimetre-waves 5G communications and far field wireless power transfer applications in Internet-of-things (IoT) sensor nodes.
With the gain enhancement of antennas the beam-width of antenna reduce as well as the coverage will also limited. Therefore, to serve the multi-users we need phased antenna arrays for point-to-point communications. The phase shifter is the key component to enable beam steering capabilities. A novel approach to design a compact broadband reconfigurable SIW phase-shifter for phased array antennas in 5G wireless communications is presented and verified by experimental analogue. In addition to SIW phase shifter, to improve the insertion loss in SIW structure due to substrate material a novel design and fabrication technique for low loss hollow integrated waveguide (HIW) based on low cost 3D printing technology is also presented. The proposed components are compact, broadband, low cost and easy to fabricate and integrate with other planar circuits.
In regard to mmW wireless power transfer applications, several compact and efficient rectennas has been designed specifically for WPT to IoT sensor nodes for structural health monitoring and inspection applications. Conformal antenna arrays and flexible rectifiers for wearable applications have also been presented. To address the issue of finite battery life of IoT sensor nodes a complete mmW far-field wireless power transfer system for WPT to IoT sensor nodes for backscattering communications is proposed and demonstrated.