Yes / Millimetre-wave frequencies are promising for sensitive detection of glucose levels in the blood, where the temperature effect is insignificant. All these features provide the feasibility of continuous, portable, and accurate monitoring of glucose levels. This paper presents a metamaterial-inspired resonator comprising five split-rings to detect glucose levels at 24.9 GHz. The plexiglass case containing blood is modelled on the sensor's surface and the structure is simulated for the glucose levels in blood from 50 mg/dl to 120 mg/dl. The novelty of the sensor is demonstrated by the capability to sense the normal glucose levels at millimetre-wave frequencies. The dielectric characteristics of the blood are modelled by using the Debye parameters. The proposed design can detect small changes in the dielectric properties of blood caused by varying glucose levels. The variation in the transmission coefficient for each glucose level tested in this study is determined by the quality factor and resonant frequency. The sensor presented can detect the change in the quality factor of transmission response up to 2.71/mg/dl. The sensor's performance has also been tested to detect diabetic hyperosmolar syndrome. The sensor showed a linear shift in resonant frequency with the change in glucose levels, and an R2 of 0.9976 was obtained by applying regression analysis. Thus, the sensor can be used to monitor glucose in a normal range as well as at extreme levels. / This study is funded by Ministry of Higher Education (MoHE) Malaysia under Fundamental Research Grant Scheme Vot No. FRGS/1/2019/TK04/UTHM/02/13, and it is partially sponsored by Universiti Tun Hussein Onn Malaysia (UTHM).

Superconductor-Insulator-Superconductor (SIS) mixers offer the best noise properties of any heterodyne mixing technique at millimetre wavelengths. In astronomy, they are used for sensitive spectroscopy, which is vital for understanding the properties of the cold interstellar medium, including regions of star formation activity. Modern SIS receivers have noise properties that are ∼3 times the quantum limit, and it is now becoming increasingly difficult to lower the noise properties any further. In this thesis, I investigate two techniques that extend the capability of SIS receivers. The first technique is extending the instantaneous bandwidth of the receivers, i.e., the intermediate frequency bandwidth (IFBW). For spectral line sources, wide IFBW expands the survey depth to allow multiple emission lines to be observed simultaneously. Here, I present a new SIS mixer device at 230 GHz. The planar circuit was minimised to reduce any parasitic capacitances that may limit the IFBW. Experimentally, the device provides excellent noise temperatures down to 36 K and an IFBW extending from approximately 0-11 GHz. Simulation software was developed to better understand the performance of this device, and it suggests that the IFBW can be extended to higher frequencies if the IF measurement chain is upgraded. The second technique that I investigate is increasing the number of receivers in the focal plane of the receiver, i.e., adding more pixels. There are many challenges involved in this task including how to fit multiple receivers into a small space, how to properly cool the receiver, and how to deliver the local-oscillator signal. Here, I present a new 1 × 4 focal plane array. This array is acting as a demonstrator for a new array architecture that can be expanded into many more pixels in the future. It uses cascaded waveguide power splitters to divide the local-oscillator signal, and then waveguide directional couplers to combine the LO with the astronomical signals. Finally, I present CO(J=1→0) measurements from 34 galaxies in the 5MUSES survey. These measurements trace the amount of cold molecular gas present in these galaxies. By comparing these measurements to other metrics that trace star formation activity (e.g., infrared luminosity), I was able to form empirical relationships between the observed quantities. I also combined these results with other star formation studies from nearby and high redshift galaxies to form scaling relationships spanning a large fraction of cosmic time.

Future 5G systems and beyond are expected to implement compact and versatile antennas in highly densifi ed millimetre-wave (MMW) wireless networks. This research emphasises on the realisation of 5G antennas provided with wide bandwidth, high gain, adaptable performance, preferably conformal implementation, and feasible bulk fabrication. Ka{band (26.5{40 GHz) is selected based on recent 5G standardisation, and novel antenna geometries are developed in this work on both rigid and flexible substrates by implementing advanced techniques of frequency reconfi guration, multiple-input-multiple- output (MIMO) assembly, as well as wideband and multiband antennas and arrays. Nove lMMW wideband antennas are presented for 5G and spatial diversity at the antenna front-ends is substantially improved by deploying wideband antennas in a MIMO topology for simultaneous multiple-channel communication. However, wideband operation is often associated with efficiency degradation, which demands a more versatile approach that allows the adaptable antenna to select the operating frequency. In this research, high performance recon figurable antennas are designed for frequency selection over Ka- {band. Also, an efficient and conformal antenna front-end solution is developed, which integrates both frequency recon guration and MIMO technology. Gain of the antenna is critically important for 5G systems to mitigate high propagation losses. Antenna design with both high gain and bandwidth is challenging as wideband antennas are traditionally gain-limited, while antenna arrays deliver high gain over a narrow bandwidth. An Enhanced Franklin array model is proposed in this thesis, which aggregates multiband response with high gain performance. Furthermore, novel flexible monopole antenna and array con gurations are realised to attain high gain profi le over the complete Ka{band. These proposed 5G antennas are anticipated as potential contribution in the progress towards the realisation of future wireless networks.

In this thesis, a fully millimetre-wave (mm-wave) generation and transmission system is proposed for futuristic communications. Significant challenges have been dealt with regarding the proposed system, including designing the mm-wave generation and transmission technique, and its application in cellular networks. These challenges are presented through five main contributions and validated via Optiwave Design Software and MATLAB simulation tools. Firstly, three novel photonic generation methods are proposed and designed based on the characteristics of Brillouin fibre laser and the Stimulated Brillouin Scattering (SBS) effects with phase modulation. The mm-wave carriers are successfully generated with a tuning capability from 5 to 90 GHz. Also, these carriers are with good Signal to Noise Ratio (SNR) up to 51 dB, and low noise signal power of about -40 dBm. The impact of these methods is obtaining stable mm-waves appropriate for Radio over Fibre (RoF) transmission systems in 5G optical networks. Secondly, a full-duplex RoF system with the generation of a 64 GHz mm-wave is proposed. Successful transmission of the mm-wave over a fibre link is achieved for up to 100 km of fibre with a data rate of 5 Gbits/s. The main impact of this system is cost reduction and performance improvement by simplifying mm-wave generation and transmission over fibre. Also, it ensures a useful communication link for small cell networks. Thirdly, a hybrid Fibre/Free-space optical (FSO) system for the generation and transmission of 64 GHz mm-wave is proposed. This optical system provides a low latency communication link and overcomes mm-wave high path losses. A successful mm-wave transmission is achieved over a 10 km fibre length, and 2 km FSO link length with a good Bit Error Rate (BER) of about 1.5×10-13 and a data rate of 10 Gbits/s. This system increases the network coverage area by transmitting the mm-wave over the FSO link to the areas with natural obstacles the laying of fibre cables impossible. Also, it can be used as an effective solution under emergency disaster conditions. Fourthly, a comprehensive study of the wireless propagation performance for different mm-wave bands (28, 60, and 73 GHz) as cellular networks is investigated and compared with the 2.4 GHz Ultra-High Frequency band (UHF). A map-based scenario is proposed for the deployment of Base Stations (BSs) within the Brunel University London Campus map to consider real blockage effects. This investigation involved specifying which mm-wave spectrum can enhance the futuristic cellular networks, by evaluating the coverage and rate trends. Comparative results show that the 73 GHz bands can achieve the higher rate with good coverage and the lowest interference effects than the other mm-wave bands. Finally, a simplified path loss model is proposed to estimate precisely the 28 GHz mm-wave performance, which is considered a key component in 5G networks in outdoor applications. The proposed path loss model captures the diffraction and specular reflection impacts on mm-wave wireless propagation.

This thesis presents the theoretical and experimental framework for the development of accurate on-wafer S-parameter and noise parameter measurements of silicon devices in the upper millimetre-wave frequency range between 70 GHz and 300 GHz. Novel integrated noise parameter test setups were developed for nanoscale MOSFETs and SiGe HBTs and validated up to 170 GHz. In the absence of accurate foundry models in this frequency range, the experimental findings of this thesis have been employed by other graduate students to design the first noise and input impedance matched W- and D-band low-noise amplifiers in nanoscale CMOS and SiGe BiCMOS technologies. The results of the D-band S-parameter characterization techniques and of the new Y-parameter based noise model have been used by STMicroelectronics to optimize the SiGe HBT structure for applications in the D-band. In the first half of the thesis, theoretical analysis indicates that, for current silicon devices, distributive effects in test structure parasitics will become significant only beyond 300 GHz. This conclusion is supported by experiments which compare the lumped-element based open-short and the transmission line based split-thru de-embedding techniques to the multiline thru-reflect-line (TRL) network analyzer calibration algorithm. Electromagnetic simulations and measurements up to 170 GHz demonstrate that, for microstrip transmission lines with metal ground plane placed above the silicon substrate, the line capacitance per unit length remains a weak function of frequency. Based on this observation, the multiline TRL algorithm has been modified to include a dummy short de-embedding structure. This allowed for the first time to perform single step calibration and de-embedding of silicon devices using on-silicon calibration standards. The usefulness of the proposed method was demonstrated on the extraction of the difficult-to-measure SiGe HBT and nanoscale MOSFET model parameters, including transcondutance delay, tau, gate resistance, source resistance, drain-source capacitance, and channel resistance, Ri. Building on the small-signal characterization technique developed in the first half, a new Y-parameter based noise model for SiGe HBTs, that includes the correlation between the base and collector shot noise currents, is proposed in the second half of the thesis along with a method to extract the noise transit time parameter. With this model, the high frequency noise parameters of a SiGe HBT can be calculated from the measured Y-parameters, without requiring any noise figure measurements. Finally, to validate the proposed noise model, the first on-wafer integrated noise parameter measurement systems were designed and measured in the W- and D-bands. The systems enable millimetre-wave noise parameter measurements with the multi-impedance method by integrating the impedance tuner and an entire millimetre-wave noise receiver on the same die as the device-under-test. Good agreement was obtained between the noise parameters calculated from the Y-parameter measurements and those obtained from direct noise figure measurements with the integrated systems. The results indicate that the minimum noise figure of state-of-the-art advanced SiGe HBTs remains below 5 dB throughout the D-band, making them suitable for a variety of commercial products in this frequency range.

This thesis presents the theoretical and experimental framework for the development of accurate on-wafer S-parameter and noise parameter measurements of silicon devices in the upper millimetre-wave frequency range between 70 GHz and 300 GHz. Novel integrated noise parameter test setups were developed for nanoscale MOSFETs and SiGe HBTs and validated up to 170 GHz. In the absence of accurate foundry models in this frequency range, the experimental findings of this thesis have been employed by other graduate students to design the first noise and input impedance matched W- and D-band low-noise amplifiers in nanoscale CMOS and SiGe BiCMOS technologies. The results of the D-band S-parameter characterization techniques and of the new Y-parameter based noise model have been used by STMicroelectronics to optimize the SiGe HBT structure for applications in the D-band. In the first half of the thesis, theoretical analysis indicates that, for current silicon devices, distributive effects in test structure parasitics will become significant only beyond 300 GHz. This conclusion is supported by experiments which compare the lumped-element based open-short and the transmission line based split-thru de-embedding techniques to the multiline thru-reflect-line (TRL) network analyzer calibration algorithm. Electromagnetic simulations and measurements up to 170 GHz demonstrate that, for microstrip transmission lines with metal ground plane placed above the silicon substrate, the line capacitance per unit length remains a weak function of frequency. Based on this observation, the multiline TRL algorithm has been modified to include a dummy short de-embedding structure. This allowed for the first time to perform single step calibration and de-embedding of silicon devices using on-silicon calibration standards. The usefulness of the proposed method was demonstrated on the extraction of the difficult-to-measure SiGe HBT and nanoscale MOSFET model parameters, including transcondutance delay, tau, gate resistance, source resistance, drain-source capacitance, and channel resistance, Ri. Building on the small-signal characterization technique developed in the first half, a new Y-parameter based noise model for SiGe HBTs, that includes the correlation between the base and collector shot noise currents, is proposed in the second half of the thesis along with a method to extract the noise transit time parameter. With this model, the high frequency noise parameters of a SiGe HBT can be calculated from the measured Y-parameters, without requiring any noise figure measurements. Finally, to validate the proposed noise model, the first on-wafer integrated noise parameter measurement systems were designed and measured in the W- and D-bands. The systems enable millimetre-wave noise parameter measurements with the multi-impedance method by integrating the impedance tuner and an entire millimetre-wave noise receiver on the same die as the device-under-test. Good agreement was obtained between the noise parameters calculated from the Y-parameter measurements and those obtained from direct noise figure measurements with the integrated systems. The results indicate that the minimum noise figure of state-of-the-art advanced SiGe HBTs remains below 5 dB throughout the D-band, making them suitable for a variety of commercial products in this frequency range.

The advantages offered by Super High Frequency (SHF) and Extremely High Frequency (EHF) bands such as large bandwidth, small antenna size, and easy installation or deployment have motivated the interest of researchers to study those factors that prevent optimum utilization of these bands. Under precipitation conditions, factors such as clouds, hail, fog, snow, ice crystals and rain degrade link performance. Rain fade, however, remains the dominant factor in the signal loss or signal fading over satellite and terrestrial links especially in the tropical and sub-tropical regions within which South Africa falls. At millimetre-wave frequencies the signal wavelength approaches the size of the raindrops, adversely impacting on radio links through signal scattering and absorption. In this work factors that may hinder the effective use of the super high frequency and extremely high frequency bands in the Southern African region are investigated. Rainfall constitutes the most serious impairment to short wavelength signal propagation in the region under study. In order to quantify the degree of impairment that may arise as a result of signal propagation through rain, the raindrops scattering amplitude functions were calculated by assuming the falling raindrops to be oblate spheroidal in shape. A comparison is made between the performance of the models that assume raindrops to be oblate spheroidal and those that assume them to be spherical. Raindrops sizes are measured using the Joss-Waldvogel RD-80 Distrometer. The study then proposes various expressions for models of raindrops size distributions for four types of rainfall in the Southern Africa region. Rainfall rates in the provinces in South Africa are measured and the result of the cumulative distribution of the rainfall rates is presented. Using the information obtained from the above, an extensive calculation of specific attenuation and phase shift in the region of Southern Africa is carried out. The results obtained are compared with the ITU-R and those obtained from earlier campaigns in the West African sub region. Finally, this work also attempts to determine and characterize the scattering process and micro-physical properties of raindrops for sub-tropical regions like South Africa. Data collected through a raindrop size measurement campaign in Durban is used to compare and validate the developed models. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2014.

This thesis describes work on the theoretical modelling and experimental measurement of the complex permittivity of dielectrics. The main focus of research has been into the characterisation of permittivity of planar and layered samples within the millimetre wave band. The measurement method is based on the free-space measurement of the transmission and reflection coefficients of samples. A novel analytical method of determining the transmission and reflection coefficients as functions of frequency arising from a generalised structure of planar dielectric layers is also described and validated. The analytical method is based on signal flow techniques. The measurement and analytical techniques have been applied in two main areas: firstly, the acquisition of new data on human skin in the band 57 to 100GHz and secondly, the detection and location of defects in composite materials for which a band of 90 to 100GHz was used. Measurements have been made on the complex permittivity of a single sample of excised human skin fixed in formaldehyde. The experimental results have been corrected to account for the fixing process in formaldehyde and are projected to body temperature. This data is, to the best of the author’s knowledge, the first of its kind to be published. Predicted skin permittivity based on various relaxation models varies widely and only partially fits the measured data. The experimental results have been used to determine the parameters of a Cole-Cole function which gives the best fit to the measured data. The measured skin data has also been used to calculate power deposition in skin exposed to millimetre wave radiation. This work concludes that a skin surface temperature rise of only 0.20C results from a thirty second exposure to signals of 100W/m2. Experimental work with fibreglass composite samples has shown that defects such as delaminations, voids, matrix cracks and improper cure result in resolvable differences in the dielectric properties of the samples at 90 – 100GHz. The measurement technique is particularly sensitive to the detection of cracks and its spatial resolution is 20mm or better. Whilst confirming the general conclusions of previously published work, the specific findings of this study are novel.

This thesis describes work on the theoretical modelling and experimental measurement of the complex permittivity of dielectrics. The main focus of research has been into the characterisation of permittivity of planar and layered samples within the millimetre wave band. The measurement method is based on the free-space measurement of the transmission and reflection coefficients of samples. A novel analytical method of determining the transmission and reflection coefficients as functions of frequency arising from a generalised structure of planar dielectric layers is also described and validated. The analytical method is based on signal flow techniques. The measurement and analytical techniques have been applied in two main areas: firstly, the acquisition of new data on human skin in the band 57 to 100GHz and secondly, the detection and location of defects in composite materials for which a band of 90 to 100GHz was used. Measurements have been made on the complex permittivity of a single sample of excised human skin fixed in formaldehyde. The experimental results have been corrected to account for the fixing process in formaldehyde and are projected to body temperature. This data is, to the best of the author’s knowledge, the first of its kind to be published. Predicted skin permittivity based on various relaxation models varies widely and only partially fits the measured data. The experimental results have been used to determine the parameters of a Cole-Cole function which gives the best fit to the measured data. The measured skin data has also been used to calculate power deposition in skin exposed to millimetre wave radiation. This work concludes that a skin surface temperature rise of only 0.20C results from a thirty second exposure to signals of 100W/m2. Experimental work with fibreglass composite samples has shown that defects such as delaminations, voids, matrix cracks and improper cure result in resolvable differences in the dielectric properties of the samples at 90 – 100GHz. The measurement technique is particularly sensitive to the detection of cracks and its spatial resolution is 20mm or better. Whilst confirming the general conclusions of previously published work, the specific findings of this study are novel.

In this work  high gain antennas are investigated for the 60 GHz frequency. The goal is to produce a high bandwidth point-to-point wireless network that could enable improved and new features in embedded systems used to detect particles in high energy physics. A literature study was performed aiming at simple, high gain, highly polarised antennas. Complex designs were grouped into three different groups: flat antenna design, build-up design and multi-antenna design. The multi-antenna design was found to have the simplest design and manufacturing but also feature larger antenna area. Three different designs were produced and tested, standard patch antenna, long patch antenna and a Vivaldi antenna. Manufacturing of a 4-patch antenna was also tested. All three demonstrated expected properties, the Vivaldi shows the best gain while the long patch antenna is slightly below the standard patch antenna. A forth design implementation was also tested using a 3D-printed lens. A lens can increase gain and allow changing beam direction. A lens was design and tested, the results showed an increased gain but with varying results at angels. Antennas were designed and manufactured using simple etching technique showing that further research can be done using simple and easily accessible techniques. Both antenna and lens show good properties and should be further investigated and validated. / I det här arbetet har antenner med hög förstärkning vid frekvensen 60 GHz undersökts. Målet är att utveckla punkt-till-punkt nätverk med hög bandbredd för detektorer i partikelkolliderare. Idag används trådade nätvärk i detektorn, genom att byta till trådlös dataöverföring kan onödig massa minskas och kvalitet förbättras. En litteraturstudie genomfördes med inriktning mot enkla, starkt förstärkande och kraftigt polariserad antenner. Tre olika typer defineras: platta designer, uppbygda designer och antenngrupper. Antenngrupper var de med enklaste design och tillverkning men också de med störst area relativt de andra. Tre olika antenner tillverkades och testades: patchantenn, lång patchantenn och Vivaldiantenn. Även en 4-patch antenn tillverkades. Produktionen av alla antenner höll hög kvalitet och de testade egenskaperna var förväntade. Vivaldiantennen hade starkast förstärkning av de testade antennerna, den långa patchantennen presterade strax under standard patchantennen. Även tester av en antenngrupp bestående av en patch antenn oc hen antennlins gjordes. Genom att använda en lins kan förstärkningen ökas och riktningen ändras. En lins designades och tillverkades med en 3D-skrivare. Resultat från tester visade på en ökad förstärkning men med varierande resultat vid vinklar. Antenner designades och tillverkades med en enkel etsningsmetod, detta visar att forsatta undersökningar kan utnyttja enkel och lättilgänlig teknik. Goda resultat uppvisades med både antenner och lins. Framtida studier kan utföras för att vidarutveckla och validera konceptet.