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  • Development of novel tumour-activated peptide prodrugs of ATR/ATM inhibitor, AZD6738

    Falconer, Robert A.; Loadman, Paul M.; Barnieh, Francis M. (University of BradfordFaculty of Life Sciences, 2019)
  • Design, synthesis and in vitro biological evaluation of potential polysialyltransferase (ST8SiaII) inhibitors

    Shnyder, Steven D.; Falconer, Robert A.; Ali, Marrwa M. (University of BradfordInstitute of Cancer Therapeutics, School of Pharmacy & Medical Sciences, Faculty of Life Sciences, 2020)
  • Modelling, Simulation, Optimisation and Thermodynamic Analysis of Multistage Reverse Osmosis Process based Brackish Water Desalination

    Mujtaba, Iqbal M.; Patel, Rajnikant; Al-Obaidi, Mudhar A.A.R.; Alsarayreh, Alanood A. (University of BradfordFaculty of Engineering and Informatics, 2020)
  • Drivers and economic consequences of quality of disclosure of non-GAAP measures

    Elshandidy, Tamer; Baimbridge, Mark J.; Dent, Aneta (University of BradfordSchool of Management, 2021)
  • Bond Performance between Corroded Steel and Recycled Aggregate Concrete Incorporating Nano Silica

    Ashour, Ashraf A.; Alhawat, Musab M. (University of BradfordFaculty of Engineering and Informatics, 2020)
    The current research project mainly aims to investigate the corrosion resistance and bond performance of steel reinforced recycled aggregate concrete incorporating nano-silica under both normal and corrosive environmental conditions. The experimental part includes testing of 180 pull-out specimens prepared from 12 different mixtures. The main parameters studied were the amount of recycled aggregate (RCA) (i.e. 0%, 25%, 50% and 100%), nano silica (1.5% and 3%), steel embedment length as well as steel bar diameter (12 and 20mm). Different levels of corrosion were electrochemically induced by applying impressed voltage technique for 2, 5, 10 and 15 days. The experimental observations mainly focused on the corrosion level in addition to the ultimate bond, failure modes and slips occurred. Experimental results showed that the bond performance between un-corroded steel and recycled aggregate concrete slightly reduced, while a significant degradation was observed after being exposed to corrosive conditions, in comparison to normal concrete. On the other hand, the use of nano silica (NS) showed a reasonable bond enhancement with both normal and RCA concretes under normal conditions. However, much better influence in terms of bond and corrosion resistance was observed under advancing levels of corrosion exposure, reflecting the improvement in corrosion resistance. Therefore, NS was superbly effective in recovering the poor performance in bond for RCA concretes. More efficiency was reported with RCA concretes compared to the conventional concrete. The bond resistance slightly with a small amount of corrosion (almost 2% weight loss), then a significant bond degradation occurs with further corrosion. The influence of specific surface area and amount of nano silica on the performance of concrete with different water/binder (w/b) ratios has been also studied, using 63 different mixtures produced with three different types of colloidal NS having various surface areas and particle sizes. The results showed that the performance of concrete is heavily influenced by changing the surface area of nano silica. Amongst the three used types of nano silica, NS with SSA of 250 m2 /g achieved the highest enhancement rate in terms of compressive strength, water absorption and microstructure analysis, followed by NS with SSA of 500 m2/g, whilst NS with SSA of 51.4 m2 /g was less advantageous for all mixtures. The optimum nano silica ratio in concrete is affected by its particle size as well as water to binder ratio. The feasibility of the impact-echo method for identifying the corrosion was evaluated and compared to the corrosion obtained by mass loss method. The results showed that the impact echo testing can be effectively used to qualitatively detect the damage caused by corrosion in reinforced concrete structures. A significant difference in the dominant frequencies response was observed after exposure to the high and moderate levels of corrosion, whilst no clear trend was observed at the initial stage of corrosion. Artificial neural network models were also developed to predict bond strength for corroded/uncorroded steel bars in concrete using the main influencing parameters (i.e., concrete strength, concrete cover, bar diameter, embedment length and corrosion rate). The developed models were able to predict the bond strength with a high level of accuracy, which was confirmed by conducting a parametric study.
  • The Empirical Study of Sustainable Energy Use and Policies in a Developing Country. The Case of Kenya Vision 2030

    Rajamani, Haile S.; Carruthers, Andrew; Nyong'a, Enock M. (University of BradfordFaculty of Engineering and Informatics, 2019)
    Recent literature has shown a close correlation between economic prosperity and the intensity of energy use in a country. In this study, an investigation to determine the extent of evolution of the concept of sustainability in the energy industry to realise the aim of Kenya Vision 2030 development blueprint is presented. In this study, journals, government reports, statutes and policies dating back to the end of the eighteenth century were reviewed to establish the research gap. Interviewing of key stakeholders in the energy industry a survey of rural, peri-urban and urban households on energy use and supply in the country and a geographical information system were methods used for data analysis. The study findings revealed that; the current energy policies are a legacy of colonial policies which benefit the urban and commercial centres along the railway line; the current policies are skewed to promoting electricity and petroleum sectors in energy industry and; biomass is the main source of fuel for rural and peri-urban households and, increased household energy demand has a negative impact on environment. In light of these findings, the practice of energy use and policies have to evolve significantly so that the aim of the Vision 2030 has to be realised. Therefore, this study is an innovative, analytical and methodological approach to sustainable energy use and policy assessment for developing countries. The study also makes contribution to the body of knowledge in the field of sustainable energy use and policies for developing countries by literature publication.
  • A critical inquiry into the nature and promise of peace education in Cambodia. Using transpection to examine the theory and praxis, context, transformative potential, and possible model of peace education in Cambodia

    McMahon, Dennis; McCravy, Samuel T. (University of BradfordDivision of Peace Studies and International Development, Faculty of Social Sciences, 2017)
    This thesis is a comparative case study which investigates both formal and nonformal peace education initiatives and situates them within the socio-political, cultural, and economic landscape of Cambodia. The research employs a participatory methodology with reflection and learning as key process components. Cambodian youth [ages 11 to 15] are the primary research subjects, and Cambodian youth [ages 18-25] are the co-researchers in this inquiry. Joint cooperation with local non-governmental organisations as the key stakeholders in this research ensure that the outcomes and findings are useful for praxis as well. Based in the ontology and epistemology of critical realism, the research investigates the practice of peace education in Cambodia. It posits the need for transpection as an analytical framework and a pedagogy which comprises retrospection [looking into the past], introspection [looking inward], extrospection [looking outward] and prospection [looking to the future]. The research describes the contextual factors that (dis)enable the practice of peace education and analyses the ways in which peace education contributes to conflict transformation at the personal, relational, structural, and cultural levels. The thesis argues that peace education in Cambodia makes a deeper impression on personal and relational conflict, but that via transformative agency and through the lens of both feminist discourse, can also make a contribution to cultural and structural conflict transformation as well. Peace education is effective insofar as it operates within an enabling environment where contexts align with mechanisms to catalyse positive change. The thesis proposes that critical peace education in Cambodia should be given greater attention and enfolded symbiotically into ongoing peacebuilding initiatives. Lastly, the model of peace education for Cambodia should be locally owned, focussed on modelling, hybrid (i.e. formal and non-formal), and transpective. That is, peace education should include study of the past, deep self-understanding, critical awareness and perspective taking, and futures thinking.
  • Farmer-pastoralist conflicts in the Kilosa district of Tanzania: A qualitative study of stakeholder perspectives on causes, impacts and responses

    Kelly, Rhys H.F.; Potts, David J.; Pankhurst, Donna T.; Ntumva, Mabebe E. (University of BradfordDivision of Peace Studies and International Development, Faculty of Management, Law and Social Sciences, 2020)
    This study applies a qualitative approach in examining the stakeholder perspectives on the causes and impacts of, and responses to, the farmer-pastoralist conflicts. The study is primarily a response to the broader stakeholder concerns surrounding the farmer-pastoralist conflicts in the Kilosa district of Tanzania. The interdisciplinary approach and, more importantly, the environmental security and political ecology theories, were used for conflict analysis in a bid to determine the gaps in the existing body of the literature. Specifically, the study aimed at determining: first, the causes of the conflicts in question driven by the growing concern around the increasing land conflicts between farmers and pastoralists in the district; second, the impacts of the conflicts and respective implications to the causes and conflict management mechanisms; third, the relevance of the conflict management mechanisms in place. The study adopted a case study design drawing from a range of qualitative methods involving semi-structured interviews and thematic analysis for collecting and analysing the stakeholder perspectives obtained from the field. The study then reveals that farmer-pastoralist conflicts in Kilosa district are mainly grounded in the broader domestic and external socio-political forces. The escalation into violence, however, depends mostly on resource scarcity driven by climate change manifesting as drought. In this regard, the lone environmental scarcity-conflict nexus is found to be less significant in causing farmer-pastoralist conflicts in Kilosa, a finding underpinning the political ecology’s structural influence. The study finds that the use of multistakeholder bricolage institutions is more relevant for addressing these conflicts in Kilosa district.
  • Peace agreement and conflict transformation: A study of the 1997 Chittagong Hill Tracts Accord of Bangladesh

    Greene, Owen J.; Islam, Md. Touhidul (University of BradfordFaculty of Management, Law and Social Sciences, 2019)
    This thesis examines how, and the extent to which, the Chittagong Hill Tracts (CHT) Accord of Bangladesh contributed to transform conflicting relations of the parties, and communities living in the CHT. This case study research has combined two methods: (i) key informant interviews and (ii) consultation of wider secondary literature, reports of accord signing parties, international organizations, NGOs and other stakeholders, newspaper articles, working papers etc. We have developed a process-oriented analytical framework through reviewing eight widely studied peace agreements and their following conflict transformation processes. This theme-based distinctive framework has guided us to conduct a comprehensive analyse of the CHT case. We argue that the 1997 CHT Accord, developed as a part of an internal strategic conflict management and negotiation process, and stipulated for limited territorial power-sharing and localized proportional power-sharing of communities, to a considerable extent helped to transform parties’ conflicting relations, and the conflict itself, despite the Accord’s limited nature and partial implementation. The post-accord immediate implementation of some key provisions helped to build confidence of the parties and engaged them in decision-making process. This restrained them not to return to violence, although an incremental accord implementation process helped to address some complexities but created contradictions and dubious relations between them over some issues. The accord considerably contributed to improve socio-economic conditions of CHT people. Nevertheless, it shifted the dynamics of original conflict towards an intra-ethnic dimension, whereas the inter-community relations remained highly polarized due to inadequate attention paid by relevant stakeholders to bridge their gaps for peace.
  • Investigation to Identify the Influence of Mannitol as a Carrier on the Ex-Vivo Dose Emission and the In-Vitro Aerodynamic Dose Emission Characteristics of Dry Powder Inhalers of Budesonide

    Assi, Khaled H.; Paluch, Krzysztof J.; Aloum, Fatima (University of BradfordSchool of Pharmacy, Faculty of Life Sciences, 2020)
    This study provides, for the first time, an ex vivo comparative evaluation of formulations of budesonide with crystallised β-form mannitol, commercial DPI grade mannitol and lactose. The lactose-budesonide was the marketed Easyhaler® 200 g formulation. Ex vivo assessment of deposition using the Easyhaler® multi-dose high resistance inhaler with reservoir was compared with the RS01® single dose capsule low resistance inhaler at two different inhalation rates. Aerodynamic characteristics, flow and surface energies were investigated together with in vitro and ex vivo assessment of drug deposition. Dose emission was greater for all formulations with higher inhalation flow, indicating greater detachment of drug from carrier, and greater with the Easyhaler®, highlighting the importance of correct device for formulation. Emission was lowest at both inhalation rates for crystallised mannitol due to poor flowability associated with elongated particle shape which resulted in interception deposition. Surface energies were also implicated; closely matched polar surface energy of carrier and drug may be an important inhibiting factor. The promising aerodynamic characteristics of crystallised mannitol with the RS01® inhaler and lactose-budesonide from in vitro assessment were not supported by ex vivo results, highlighting the need for careful selection of device.
  • Comparative Analysis of Machine Learning Algorithms on Activity Recognition from Wearable Sensors’ MHEALTH dataset Supported with a Comprehensive Process and Development of an Analysis Tool

    Qahwaji, Rami S.R.; Kamala, Mumtaz A.; Sheraz, Nasir (University of BradfordFaculty of Engineering and Informatics, 2019)
    Human activity recognition based on wearable sensors’ data is quite an attractive subject due to its wide application in the fields of healthcare, wellbeing and smart environments. This research is also focussed on predictive performance comparison of machine learning algorithms for activity recognition from wearable sensors’ (MHEALTH) data while employing a comprehensive process. The framework is adapted from well-laid data science practices which addressed the data analyses requirements quite successfully. Moreover, an Analysis Tool is also developed to support this work and to make it repeatable for further work. A detailed comparative analysis is presented for five multi-class classifier algorithms on MHEALTH dataset namely, Linear Discriminant Analysis (LDA), Classification and Regression Trees (CART), Support Vector Machines (SVM), K-Nearest Neighbours (KNN) and Random Forests (RF). Beside using original MHEALTH data as input, reduced dimensionality subsets and reduced features subsets were also analysed. The comparison is made on overall accuracies, class-wise sensitivity and specificity of each algorithm, class-wise detection rate and detection prevalence in comparison to prevalence of each class, positive and negative predictive values etc. The resultant statistics have also been compared through visualizations for ease of understanding and inference. All five ML algorithms were applied for classification using the three sets of input data. Out of all five, three performed exceptionally well (SVM, KNN, RF) where RF was best with an overall accuracy of 99.9%. Although CART did not perform well as a classification algorithm, however, using it for ranking inputs was a better way of feature selection. The significant sensors using CART ranking were found to be accelerometers and gyroscopes; also confirmed through application of predictive ML algorithms. In dimensionality reduction, the subset data based on CART-selected features yielded better classification than the subset obtained from PCA technique.
  • Crafting the Self: How participating in coaching conversations can shape a recipient’s learning

    Sullivan, Paul W.; Stokes, Paul; Dennison, Melissa (University of BradfordFaculty of Management, Law and Social Science, 2020)
    This research contributes to current understandings of how the process of learning unfurls temporally during coaching conversations. This experience has been obtained through first-hand lived experience, in particular, my active participation as a coachee in a series of one-to-one coaching conversations with two professional coaches. To assist in developing and enriching these understandings further I have crafted a research design with a two-stage process. And a hybrid methodology drawn from Interpretative Phenomenological Analysis and Dialogical Methods. This approach is beneficial in enabling the complexity of self-other relationships that unfold within coaching conversations to be fully articulated. I have chosen to adopt autoethnography as a research method in stage one of this research, and interviews in stage two, respectively. Autoethnography enables a complex exploration of first-hand lived experience, providing a forum in which reflexive dialogues between self and other can emerge. Thus, allowing multiple perspectives to be heard. In stage two I have interviewed 6 professional coaches, facilitating an additional dialogue to unfold between self and others, enriching this research. Critically, within this research, the self is described as malleable and non-identical with itself, where on encountering others in external and inner dialogues it experiences challenges and struggles with the unknown and unfamiliar. Significantly, through this experience the self is transformed. Finally, this process can be understood as artistic, since this research describes an aesthetic metaphor informed by Bakhtin and Gell, in which coach and coachee - described as the recipient are actively engaged in emotionally crafting and shaping the other.
  • A novel solvent-free high shear technology for the preparation of pharmaceutical cocrystals

    Paradkar, Anant R.; Kelly, Adrian L.; Mohammed, Azad F. (University of BradfordFaculty of Life Sciences, 2020)
    High shear melt granulation (HSMG) is an established technology for a production of densified granules. In this project, it was used as a novel solvent-free method for the preparation of cocrystals. Cocrystals produced by HSMG were compared to those prepared by Hot Melt Extrusion (HME) to investigate the influence of variable parameters and conditions on the process of cocrystal conversion. The potential for the active control of cocrystals polymorphism utilising the intrinsic properties of lipids was also investigated in this project. Different cocrystal pairs were prepared by both cocrystallisation methods using glycol derivative polymers. Thermal analysis, powder X-ray diffraction and Raman spectroscopy were used as analytical techniques to determine the cocrystal yield and purity. The results obtained from HSMG suggest that sufficient binder concentrations (above 12.5% w/w) in a molten state and continuous shearing force are necessary to achieve a complete cocrystals conversion. Further increase in binder concentration (15% w/w) was found to provide more regular shape and smooth surface to the prepared spherical granules. Cocrystals preparation by HME was achievable after introducing a mixing zone to the extruder configuration (Conf B and Conf C) providing densified extrudates containing pure cocrystals. In conclusion, HSMG was found as a versatile technique for the preparation of pure pharmaceutical cocrystals embedded in polymer matrix within a spherical shape granule of smooth surfaces, providing additional desirable characteristics. Intensive surface interaction, enhanced by sufficient mixing under optimal parameters, was found as a key influencing factor in cocrystallisation. Cocrystals polymorphism was actively controlled by employing the intrinsic properties of polymers and lipids.
  • Polycyclic Aromatic Hydrocarbons In Urban Soils From West Yorkshire, UK. Investigation into Abundances, Sources and Determining Factors

    Hale, William H.G.; Stern, Ben; Hamed, Heiam A.M. (University of BradfordFaculty of Life Sciences, 2018)
    This study aims to determine the concentration of 16 Polycyclic Aromatic Hydrocarbons (PAHs) in urban soils from West Yorkshire in order to determine what the factors are controlling their distribution and abundances. Although PAHs have been reported before from soils and sediments, the majority of these studies have come from China, sometimes with contrasting results, which emphasises the need to obtain equivalent data from other areas. Therefore this work provides the first measurements of their type from the area studied. Soil samples were collected from one hundred sites across an area from Bradford to Leeds on two occasions, one in autumn and one in the following summer. The soil samples were analyzed by X-ray diffraction and all found to have similar mineralogical composition, which was mainly silica and calcite. Trials using iodine as a marker for PAHs showed there were notable interactions between the minerals and PAHs, with calcium carbonate absorbing PAHs much more than silica. There is a negative correlation between the soil organic content (determined by loss on ignition) and PAHs, which confirms the PAH-mineral interaction. Gas chromatography with mass spectrometry (GC-MS) using targeted selected ion monitoring was used to determine and quantify PAHs in the one hundred soil samples with the aid of PAH external standards. The results showed highest concentrations of total PAHs in the same sample from Leeds from the autumn (1,525 ng/g) and in the summer (1,768 ng/g). In Bradford there was only moderate pollution of PAHs, the maximum being 122 ng/g. However the majority of data from Bradford showed lower levels of pollution in both summer and autumn. On the basis of prior published information, the ratio of these compounds has been used to help in identifying sources. In the samples collected from Bradford in both seasons and Leeds in autumn the PAH pollution originated from pyrogenic, biomass and petroleum combustion, however in the summer the source appeared more to be from a petrogenic source. These ratios in the samples which were collected from the area between Bradford and Leeds implied pyrogenic, biomass source of pollution in the autumn, but in the summer another source of organic compounds was indicated namely petroleum combustion. When the locations were resampled nine months later, after taking into account within-site variability, there was a strong indication that the PAH concentrations were higher. This might have been due to a seasonal effect, but when a further (third) subsample was taken at a later date it showed a further increase in PAH level which suggests the effect is accumulative rather than seasonal. The results were analysed using Principal Component Analysis (PCA) to determine whether the type of road had an effect on the concentration of the 16 PAHs compounds, but it was concluded that there was no such effect. However, the distance from the soil sample to the nearest road did have an effect on the concentration of the 16 PAH compounds, especially in soil samples having the shortest distance to the road. Traffic volume was also tested and found to influence the PAH concentrations. It is notable that, comparing the groupings from autumn with those from summer by cluster analyses, they largely had the same compounds grouping together in both cases; only two compounds differed at all in where they occurred in the clusters, with consistent patterns of grouping found for the other compounds. These analyses indicate that PAH compounds behave in a consistent way amongst groups of PAH compounds. The grouping of PAHs appears linked to their sources rather than number of rings or molecular weight.
  • The Role of Leaders and Intrapreneurial Employees in Large Technology Corporations: A Qualitative Study

    Sivarajah, Uthayasankar; Mahroof, Kamran; Anand, Chitra (University of BradfordFaculty of Management, 2020)
    Over the past 15 years, technological change has introduced an unprecedented amount of competition in the global marketplace. Large corporations are at risk of disruption by global competitors, particularly the start-up community. In today’s highly competitive environment, the goal of every business is to get ahead: this is known as ‘competitive advantage.’ One way to foster competitive advantage is through innovation—the process of change, be it a new product, idea, or method. It can mean adapting the work environment to deliver an improved service or altering the business model. Large corporations are scalable business models by design. When a company establishes a successful business model, it monetizes that model to the fullest extent, supporting the model via corporate structures, processes, tools, and cultures. These companies now face a conundrum: the policies and procedures that make them efficient also stifle innovation, which is critical to business success in today’s ultra-competitive and ever-changing market. Large companies find it especially challenging to innovate successfully within the confines of massive, bureaucratic operational structures. Since most companies are designed to deliver under their current structures, any innovation that requires a change in business model or approach requires structural changes within the company. “Intrapreneurship,” also known as corporate entrepreneurial behaviour, has the potential to resolve the issues of innovation in large corporations. Intrapreneurship is a major competitive differentiator: benefits include increased economic growth, greater efficiency, the ability to manage change effectively, greater employee engagement and development, the ability to attract and retain entrepreneurial leaders, and sustainable growth. However, organizations are not aware of how to cultivate an intrapreneurial environment. In fact, organizations often unintentionally cultivate the opposite, by adopting risk-adverse policies, limiting corporate experimentation. The extant literature examines intrapreneurship at a firm level; however, there is limited literature identifying intrapreneurial traits at an employee level. It is these employee traits and behaviours that enable organizations to act intrapreneurially, resulting in value creation for organizations. Leadership engagement as it relates to intrapreneurship is also an area that is under researched. The support of leaders in innovation efforts is crucial for intrapreneurial employees to thrive and take ideas from a place of conception to implementation. This study takes a qualitative, approach, including semi-structured interviews of employees of a large technological firm and five semi-structured interviews with executives from media, technology, and finance industries. This research identifies specific traits of employees of intrapreneurial employees, including their behaviours and attributes. This research places the employee at the heart of the organization while positioning leaders and cultural elements on the periphery. It identifies curiosity, skilled risk taking, and experimentation as core intrapreneurial traits. This study also identifies the traits and behaviours of successfully intrapreneurial organizations and the role that leadership plays in supporting and developing intrapreneurial environments and cultures. Leadership has significant and positive relations with both empowerment and an innovation-supporting organizational climate. Top managers' leadership style has been identified as being one of the most important factors—if not the most important—when it comes to driving innovation. The findings from this research indicate that leaders need to play more of an active role in developing intrapreneurial activity. They need to evolve their role into shepherds who guide intrapreneurs in navigating the corporate immune systems. This research also evolves the conceptual framework of Antoncic and Hisrich (2001) by adding employee traits and leadership as new paradigms.
  • Investigations into the Impact of Modifiable Dietary Components on Cognition. Fish, the Vegan Diet and Lifestyle Factors

    Lesk, Valerie E.; Walters, Elizabeth R.; Ryan, Clarice A. (University of BradfordFaculty of Management, Law and Social Sciences, 2020)
    The burden of neurocognitive diseases, such as Alzheimer’s, is of global concern and points to an urgent need for accurate detection and prevention strategies. This thesis investigated dietary components, in particular those that affect vitamin B levels, such as white fish consumption and veganism, which have the potential to alter cognitive outcomes in the population. Also investigated were external factors, significantly caffeine consumption, time of day, and quantity of sleep, not associated with age-related impairment, that can alter neuropsychological test performance. The literature reveals that short, multi-domain cognitive tests are commonly used for dementia screening; this study has focused exclusively on cognitive domains associated with the early stages of Alzheimer’s disease. Cognitively healthy adults were assessed using a cognitive test battery that focused on memory and processing speed. Memory test scores improved by 0.03 points for every gram of white fish consumed, whilst participants following a vegan diet scored significantly worse on tests of composite memory than their omnivorous counterparts. Interaction tests showed that prior caffeine consumption improved short-term memory test scores up to age 70. Participants of all ages performed best at their age-optimal times and further improved for immediate word recall tests with prior caffeine consumption. Processing speed scores increased linearly with hours of sleep. The results of this thesis suggest that nutrition and external factors have a significant impact on cognitive test performance. These novel findings have implications for research, diagnosis and prevention of chronic neurological disease, and public health guidance relating to cognitive function, for all ages.
  • Design of New, Compact and Efficient Microstrip Filters for 5G Wireless Communications. Design, Simulation, Implementation and Measurement of Efficient, Compact, Multi-standard, and Reconfigurable/Tunable Microstrip Filters and their Integration with Patch Antennas for Current and Future Wireless Communications

    Abd-Alhameed, Raed A.; Noras, James M.; Al-Yasir, Yasir I.A. (University of BradfordFaculty of Engineering and Informatics, 2020)
    The electromagnetic spectrum is becoming increasingly congested due to the rapid development of wireless and mobile communication in recent decades. New, compact and efficient passband filters with multi-functions and good performance are highly demanded in current and future wireless systems. This has also driven considerable technological advances in reconfigurable/tunable filter and filtering antenna designs. In light of this scenario, the objectives of this thesis are to design, fabricate and measure efficient, compact, multi-standard, and reconfigurable/tunable microstrip resonator filters and study the integration of the resonators with patch antennas. As a passive design, a compact dual-band filter is implemented to cover 2.5 to 2.6 GHz and 3.4 to 3.7 GHz for 4G and 5G, respectively. Another design is also presented with the advantages of a wide passband of more than 1 GHz. Conversely, new and compact reconfigurable filters are designed using varactor and PIN diodes for 4G and 5G. The proposed filters are tunable in the range from 2.5 to 3.8 GHz. The bandwidth is adjustable between 40 and 140 MHz with return losses between 17 to 30 dB and insertion loss of around 1 dB. Also, the thesis investigates the design of cascaded and differentially-fed filtering antenna structures. The cascaded designs operate at 2.4 and 6.5 GHz and have a relatively wide-band bandwidth of more than 1.2 GHz and a fractional bandwidth of more than 40%. For the differentially-fed structures, good performance is achieved at the 3.5 GHz with a high realized gain of more than 7.5 dBi is observed.
  • Investigation and design of 5G antennas for future smartphone applications. Simulation, Design, and Measurement of New and Compact 5G Antennas and Investigation of Their Fundamental Characteristics for Future Smartphone Applications

    Abd-Alhameed, Raed A.; Noras, James M.; Ojaroudi Parchin, Naser (University of BradfordFaculty of Engineering and Informatics, 2020)
    The fifth-generation (5G) wireless network has received a lot of attention from both academia and industry with many reported efforts. Multiple-input-multiple-output (MIMO) is the most promising wireless access technology for next-generation networks to provide high spectral and energy efficiency. For handheld devices such as smartphones, 2×2 MIMO antennas are currently employed in 4G systems and it is expected to employ a larger number of elements for 5G mobile terminals. Placing multiple antennas in the limited space of a smartphone PCB poses a significant challenge. Therefore, a new design technique using dual-polarized antenna resonators for 8×8 MIMO configuration is proposed for sub 6 GHz 5G applications. The proposed MIMO configuration could improve the channel capacity, diversity function, and multiplexing gain of the smartphone antenna system which makes it suitable for 5G applications. Different types of new and compact diversity MIMO antennas with Patch, Slot, and Planar inverted F antenna (PIFA) resonators are studied for different candidate bands of sub 6 GHz spectrum such as 2.6, 3.6, and 5.8 GHz. Unlike the reported MIMO antennas, the proposed designs provide full radiation coverage and polarization diversity with sufficient gain and efficiency values supporting different sides of the mainboard. Apart from the sub 6 GHz frequencies, 5G devices are also expected to support the higher bands at the centimeter/millimeter-wave spectrums. Compact antennas can be employed at different portions of a smartphone board to form linear phased arrays. Here, we propose new linear phased arrays with compact elements such as Dipole and Quasi Yagi resonators for 5G smartphones. Compared with the recently reported designs, the proposed phased arrays exhibit satisfactory features such as compact size, wide beam steering, broad bandwidth, end-fire radiation, high gain, and efficiency characteristics. The proposed 5G antennas can provide single-band, multi-band, and broad-band characteristics with reduced mutual coupling function. The fundamental characteristics of the 5G antennas are examined using both simulations and measurements and good agreement is observed. Furthermore, due to compact size and better placement of elements, quite good characteristics are observed in the presence of the user and the smartphone components. These advantages make the proposed antennas highly suitable for use in 5G smartphone applications.

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