Abstract:
Sub-8 GHz wireless communication networks are experiencing significant spectral
congestions as the number of personal wireless devices in the Small-Office/Home-
Office (SOHO) environments exponentially increase. Fifth-generation (5G) wireless
systems aim to address this problem by utilising the sparsely used millimetre-wave
bands. However, coverage in SOHO environments is intermittent at these bands,
owing to signals being more sensitive to shadowing and blockages. As such, this
thesis investigates strategies for modelling and improving coverage for successful
deployments of 5G systems in these environments.
A three-dimensional coverage modelling strategy to predict shadowed regions in an
office has been developed using geometrical optics, and coverage from omnidirectional
antennas deployed within the office analysed. It is shown that coverage can
be significantly improved without relocating the antenna if the structure can be
configured to radiate signal from a less cluttered location.
A tapered Leaky-Wave Antenna based on the Half-Mode Substrate Integrated Waveguide
(HMSIW-LWA) that can potentially improve coverage in the office was investigated.
However, it is shown that an omnidirectional HMSIW-LWA is challenging
to realise at millimetre-wave frequencies. Instead, two variants of HMSIW-based
antenna design with coupled printed antennas (HMSIW-CPA) that overcome these
limitations are proposed. Each HMSIW-CPA variant can either couple patch antennas
anywhere (CoRA) or at discrete points (DiRA) on the structure. DiRA has
demonstrated the most promising performance for indoor applications, as the structure
radiates 95% of the input power while maintaining a largely omnidirectional
radiation pattern.
