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Space-borne satellite radar is an important technology to measure properties of the Earth surface. However, existing radar satellites are relatively large, heavy and expensive. Current satellite radar missions employ either only a single satellite platform or a small constellation of two satellites. For these missions the revisit period, i.e. the time between satellite passes over one target region, is often ten days or more. However, it is desirable to observe targets much more frequently. Rapid information can be obtained by using large numbers of satellites that allow one particular region to be overpassed more frequently than with a single satellite. Inexpensive nano-satellites employing commercial-off-the-shelf components are the ideal platform for these constellations. The small physical size of nano-satellites places significant constraints on the design of radar systems. The miniaturization of SAR systems to fit on a CubeSat requires new technological breakthroughs that go beyond state-of-the-art.
Objectives: The aim of this PhD project is to develop a novel miniaturised radar front-end suitable for a nano-satellite, particularly focusing on approaches to reduce the number of RF beam-forming chains required and understanding the engineering trade-offs. Applicants must have a background in electrical/electronics engineering and ideally experience with designing RF circuits. A tax-free stipend of $NZD 28,200 per year is available for 3 years.
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Millimetre-Wave Communication Systems Engineering
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This project will investigate the use of millimetre-waves for extremely high data-rate wireless communication systems. Of particular interest are millimetre-wave systems operating in the 60 GHz frequency band where considerable bandwidth is available, compared to the lower microwave bands (1-6 GHz) that are currently used for most wireless systems. However, the step to millimetre-wave wireless systems entails a number of research challenges.
Objectives: The first stage of the project will involve the design and hardware implementation of a millimetre-wave hardware testbed operating in the 60 GHz band. In the second stage, the project will focus on using the hardware testbed to experimentally investigate aspects of millimetre-wave systems, e.g., receiver architectures, modulation schemes, and/or beam-steering algorithms.
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Reflectarray Antennas for Indoor Millimetre-Wave Systems
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The considerable bandwidth available at mmWave frequencies has the potential to deliver wireless systems with transmission rates comparable to wired systems, and enables new applications. However, moving from the conventional sub-6 GHz to mmWave frequency-bands introduces a number of significant challenges for antenna design. To overcome the increased propagation loss, future mmWave systems require highly directional 'steerable' antennas. This project will investigate reflectarray antennas, which offer the ability to create very directional beams that can be electronically steered to achieve area coverage.
Objectives:
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True Full-Duplex Wireless Communications
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The limited availability of suitable radio frequency spectrum has renewed interest in physical-layer technologies to improve spectral efficiency. One of the most promising techniques is 'true' full-duplex communication, where transmission and reception can occur simultaneously in the same frequency band. The practical realisation of full-duplex systems requires the strong self-interference signal (arising from the closely coupled transmitter and receiver circuits) to be suppressed, ideally to the noise-floor.
Objectives:
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Uncertainty Quantification in Computational Electromagnetics
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Computational techniques are widely used to analyze and design electromagnetic structures and devices. However, uncertainties in the description of the problem (e.g., fabrication tolerances, temperature, and material properties) are difficult to include in most computational methods. Currently, Monte-Carlo techniques are used to estimate the impact of input uncertainties, however, these are slow to converge and require multiple simulation runs.
Objectives: This project will investigate new and novel approaches to more efficiently include uncertainties in computational electromagnetic techniques using Polynomial Chaos.
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Inverse Scattering Problems in the Presence of Uncertainty
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Inverse scattering problems arise when electromagnetic waves are used to image 'hidden' objects, e.g., buried landmines, underground oil reserves, or tumours in the body. Inverse problems in electromagnetics are considerably more difficult to solve than the corresponding forward problems, as wave scattering leads to non-linear partial differential equations for the inverse operators. Existing analytical inversion techniques applied to electromagnetic imaging often fail for 'ill-posed' scenarios, particularly when parameters of the problem are uncertain.
Objectives: The aim of this project is to investigate computationally efficient techniques to explore the multi-dimensional parameter space created by the uncertainties in inverse scattering problems. In particular, the specific objectives are to develop new numerical methods for computational electromagnetics where the inputs are probabilistic measures, instead of exact numerical values.
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