Bradford Scholars

Bradford Scholars is the University of Bradford online research archive. Access is free to anyone interested in research being conducted at Bradford. In the repository you will find a range of materials from journal articles and conference papers to research reports and theses.

Contact the repository team via openaccess@bradford.ac.uk with any queries about Open Access or how to deposit your research papers.

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  • PublicationOpen Access
    Design of New, Compact and Efficient Microstrip Filters for 5G Wireless Communications
    (2020) Al-Yasir, Yasir; Abd-Alhameed, Raed; Noras, James M.
    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.
  • PublicationRestricted
    AOA localization for vehicle-tracking systems using a dual-band sensor array
    (2020-08) Al-Sadoon, Mohammed A.G.; Asif, Rameez; Al-Yasir, Yasir; Abd-Alhameed, Raed; Excell, Peter S.
    The issue of asset tracking in dense environments where the performance of the global positioning system (GPS) becomes unavailable or unreliable is addressed. The proposed solution uses a low-profile array of antenna elements (sensors) mounted on a finite conducting ground. A compact-size sensor array of six electrically small dual-band omnidirectional spiral antenna elements was designed as a front end of a tracker to operate in the 402 and 837 MHz spectrum bands. For the lower band, a three-element superposition method is applied to support estimation of the angle of arrival (AOA), whereas all six sensors are employed for the higher band. A low complexity and accurate AOA determination algorithm is proposed, the projection vector (PV), and this is combined with the array mentioned. Orthogonal frequency division multiplexing (OFDM) is integrated with the PV technique to increase the estimation resolution. The system was found to be suitable for installation on the roof of vehicles to localize the position of assets. The proposed system was tested for the tracking of nonstationary sources, and then two scenarios were investigated using propagation modeling software: outdoor to outdoor and outdoor to indoor. The results confirm that the proposed tracking system works efficiently with a single snapshot.
  • PublicationRestricted
    Detection and Diagnosis of Stator and Rotor Electrical Faults for Three-Phase Induction Motor via Wavelet Energy Approach
    (2022) Hussein, A.M.; Obed, A.A.; Zubo, R.H.A.; Al-Yasir, Yasir; Saleh, A.L.; Fadhel, H.; Sheikh-Akbari, A.; Mokryani, Geev; Abd-Alhameed, Raed
    This paper presents a fault detection method in three-phase induction motors using Wavelet Packet Transform (WPT). The proposed algorithm takes a frame of samples from the three-phase supply current of an induction motor. The three phase current samples are then combined to generate a single current signal by computing the Root Mean Square (RMS) value of the three phase current samples at each time stamp. The resulting current samples are then divided into windows of 64 samples. Each resulting window of samples is then processed separately. The proposed algorithm uses two methods to create window samples, which are called non-overlapping window samples and moving/overlapping window samples. Non-overlapping window samples are created by simply dividing the current samples into windows of 64 sam-ples, while the moving window samples are generated by taking the first 64 current samples, and then the consequent moving window samples are generated by moving the window across the current samples by one sample each time. The new window of samples consists of the last 63 samples of the previous window and one new sample. The overlapping method reduces the fault detection time to a single sample accuracy. However, it is computationally more expensive than the non-overlapping method and requires more computer memory. The resulting window sam-ples are separately processed as follows: The proposed algorithm performs two level WPT on each resulting window samples, dividing its coefficients into its four wavelet subbands. Infor-mation in wavelet high frequency subbands is then used for fault detection and activating the trip signal to disconnect the motor from the power supply. The proposed algorithm was first implemented in the MATLAB platform, and the Entropy power Energy (EE) of the high frequen-cy WPT subbands' coefficients was used to determine the condition of the motor. If the induction motor is faulty, the algorithm proceeds to identify the type of the fault. An empirical setup of the proposed system was then implemented, and the proposed algorithm condition was tested under real, where different faults were practically induced to the induction motor. Experimental results confirmed the effectiveness of the proposed technique. To generalize the proposed meth-od, the experiment was repeated on different types of induction motors with different working ages and with different power ratings. Experimental results show that the capability of the pro-posed method is independent of the types of motors used and their ages.
  • PublicationOpen Access
    An investigation on the effects of beam squint caused by an analog beamformed user terminal utilizing antenna arrays
    (IEEE, 2023-09) Abd-Alhameed, Raed; Hu, Yim Fun; Al-Yasir, Yasir; Parchin, N.O.; Ullah, Atta
    In the equivalent frequency-based model, the antenna array gain is utilised to characterise the frequency response of the beam squint effect generated by the antenna array. This impact is considered for a wide range of uniform linear array (ULA) and uniform planar array (UPA) designs, including those with and without tapering configurations. For a closer look at how the frequency response of the array adapts to the variations in the incidence angle of the signal, the bandwidth of the spectrum is varied and investigated. To study this effect, we have considered using the gain array response as an equivalent channel model in our approach. Beam squinting caused by distortion in the frequency response gain can be verified by one of two equalisers: a zero-forcing (ZF) equaliser or a minimum mean square error (MMSE) equaliser. Different cases with their analysis and results are studied and compared in terms of coded and uncoded modulations.
  • PublicationOpen Access
    Design of multi-standard single/tri/quint-wideband asymmetric stepped-impedance resonator filters with adjustable TZs
    (IET Microwaves, Antennas & Propagation, 2019-08) Al-Yasir, Yasir; Tu, Yuxiang X.; Bakr, M.S.; Ojaroudi Parchin, Naser; Asharaa, Abdalfettah S.; Mshwat, Widad F.A.G.A.; Abd-Alhameed, Raed; Noras, James M.
    This study presents an original asymmetric stepped-impedance resonator filter combined with meander coupled-line structures and enabling the realisation of finite transmission zeros (TZs) and the implementation of multi-band bandpass filters. The meander coupled sections (MCSs) tune the TZs and resonant frequencies: with higher-order spurious frequencies cancelled by the TZs, a single wideband with wide stopband from 1.18 to 1.84 GHz is possible. Furthermore, by positioning the finite TZs between the high-order spurious frequencies and adjusting the coupling strength between resonators, a quint-wideband filter can be realised, with centre frequencies of 1.19, 4.29, 5.43, 6.97, 9.9 GHz and fractional bandwidths of 31.9, 15.4, 15.8, 4.3, 39.2%, respectively. More importantly, two filters with single/quad-wideband performance can be realised by tuning the parameters of the MCS, and therefore they can be designed separately by using only one original structure. The triple-wideband filter is realised with the help of the asymmetric parallel uncoupled microstrip section. These filter structures enjoy the advantage of single/multi-band versatility, structure reusability and simplicity. The good in-band and out-of-band performance, low loss and simple structure of the proposed single/tri/quint-wideband filters make them very promising for applications in future multi-standard wireless communication.
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