Papers by Augustine O. Nwajana, PhD, FHEA, SMIEEE
Journal of Engineering, 2025
Antennas and filters are two key components that make up the configuration of the radio frequency... more Antennas and filters are two key components that make up the configuration of the radio frequency (RF) front end of any wireless communication system. While the antenna is responsible for transmitting and receiving signals in the system, the filter is tasked with selecting signals that fall within the system's operating frequency band, while also rejecting spurious (out-of-band) signals from the system. Following the recent increasing trend toward device simplicity and miniaturization, it is desirable to integrate the antenna and the filter into a single component that achieves both the radiating (i.e., transmitting and receiving) and the filtering functions simultaneously. This integrated component is what is now known as a filtering antenna (or filtenna). The filtenna reduces a system's prefiltering requirements and improves the noise performance of the system. It also finds application in overcoming the insufficiency of stand-alone bandpass filters in suppressing interference in sidebands. This article covers the review of the current state of the art in the design and implementation of filtennas, the practical applications, recent developments, and challenges. Emerging research and future opportunities in filtering antenna design and implementation techniques are also investigated and reported.
Electronics MDPI, 2025
Millimeter-wave frequencies are crucial for meeting the high-capacity, low-latency demands of 5G ... more Millimeter-wave frequencies are crucial for meeting the high-capacity, low-latency demands of 5G communication systems, thereby driving the need for compact, high-gain antenna arrays capable of efficient beamforming. This paper presents the design, simulation, fabrication, and experimental validation of a compact, high-efficiency 1 × 6 linear seriesfed microstrip patch antenna array for 5G millimeter-wave communication operating at 28 GHz. The proposed antenna is fabricated on a low-loss Rogers RO3003 substrate and incorporates an integrated symmetric two-way microstrip power divider to ensure balanced feeding and phase uniformity across elements. The antenna achieves a simulated peak gain of 11.5 dBi and a broad simulated impedance bandwidth of 30.21%, with measured results confirming strong impedance matching and a return loss better than-20 dB. The far-field radiation patterns demonstrate a narrow, highly directive beam in the E-plane, and the H-plane results reveal beam tilting behavior, validating the antenna's capability for passive beam steering through feedline geometry and element spacing (~0.5λ). Surface current distribution analysis confirms uniform excitation and efficient radiation, further validating the design's stability. The fabricated prototype shows excellent agreement with the simulation, with minor discrepancies attributed to fabrication tolerances. These results establish the proposed antenna as a promising candidate for applications requiring compact, high-gain, and beam-steerable solutions, such as 5G mm-wave wireless communication systems, point-to-point wireless backhaul, and automotive radar sensing.
Telecom, 2025
The increasing demand for sustainable and renewable energy solutions has made radio frequency ene... more The increasing demand for sustainable and renewable energy solutions has made radio frequency energy harvesting (RFEH) a promising technique for powering low-power electronic devices. RFEH captures ambient RF signals from wireless communication systems, such as mobile networks, Wi-Fi, and broadcasting stations, and converts them into usable electrical energy. This approach offers a viable alternative for battery-dependent and hardto-recharge applications, including streetlights, outdoor night/security lighting, wireless sensor networks, and biomedical body sensor networks. This article provides a comprehensive review of the RFEH techniques, including state-of-the-art rectenna designs, energy conversion efficiency improvements, and multi-band harvesting systems. We present a detailed analysis of recent advancements in RFEH circuits, impedance matching techniques, and integration with emerging technologies such as the Internet of Things (IoT), 5G, and wireless power transfer (WPT). Additionally, this review identifies existing challenges, including low conversion efficiency, unpredictable energy availability, and design limitations for small-scale and embedded systems. A critical assessment of current research gaps is provided, highlighting areas where further development is required to enhance performance and scalability. Finally, constructive recommendations for future opportunities in RFEH are discussed, focusing on advanced materials, AI-driven adaptive harvesting systems, hybrid energy-harvesting techniques, and novel antenna-rectifier architectures. The insights from this study will serve as a valuable resource for researchers and engineers working towards the realization of self-sustaining, battery-free electronic systems.
Engineering Reports, 2025
In the rapidly evolving landscape of 5G/6G networks, efficient resource optimization is critical ... more In the rapidly evolving landscape of 5G/6G networks, efficient resource optimization is critical to addressing the escalating demands for high-speed, low-latency, and energy-efficient communication. This study explores the integration of Radio Frequency Identification (RFID) technology as a novel approach to enhance resource management in 5G networks. The motivation behind this research lies in overcoming persistent challenges such as spectrum congestion, high latency, and inefficient load balancing, which impede the performance of traditional resource allocation methods. To achieve this, RFID tags were embedded in critical network components, including user devices, base stations, and Internet of Things (IoT) nodes, enabling the collection of real-time data on device status, location, and resource utilization. RFID readers strategically placed across the network continuously captured this data, which was processed by a centralized controller using a custom-designed optimization algorithm. This algorithm dynamically managed key network resources, including spectrum allocation, load balancing, and energy consumption, ensuring efficient operation under varying network conditions. Simulations were conducted to evaluate the performance of the RFID-based model against traditional 4G dynamic resource allocation techniques. The results demonstrated substantial improvements in key performance metrics. The proposed system achieved a 25% increase in spectrum utilization, a 30% reduction in average latency, a 15% boost in network throughput, and a 20% decrease in overall energy consumption. These gains highlight the effectiveness of the RFID-based optimization model in meeting the stringent performance requirements of 5G networks, particularly in high-density deployments. This study provides a scalable, cost-effective solution for optimizing resource management in 5G and lays the groundwork for future advancements in 6G networks. By leveraging real-time data and intelligent resource allocation, the proposed model addresses critical challenges in modern communication systems, ensuring enhanced network efficiency, reliability, and sustainability.
Energies, 2025
Wireless rechargeable sensor networks (WRSNs) have emerged as a critical infrastructure for monit... more Wireless rechargeable sensor networks (WRSNs) have emerged as a critical infrastructure for monitoring and collecting data in large-scale and dynamic environments. The energy autonomy of sensor nodes is crucial for the sustained operation of WRSNs. This paper presents a comprehensive survey on the state-of-the-art approaches and technologies in on-demand energy provisioning in large-scale WRSNs. We explore various energy harvesting techniques, storage solutions, and energy management strategies tailored to the unique challenges posed by the dynamic and resource-constrained nature of WRSNs. This survey categorizes existing literature based on energy harvesting sources, including solar, kinetic, and ambient energy, and discusses advancements in energy storage technologies such as supercapacitors and rechargeable batteries. Furthermore, we investigate energy management techniques that adaptively balance energy consumption and harvesting, optimizing the overall network performance. In addition to providing a thorough overview of existing solutions, this paper identifies opportunities and challenges in the field of on-demand energy provisioning for large-scale WRSNs. By synthesizing current research efforts, this survey aims to provide insight to researchers and policymakers in understanding the landscape of on-demand energy provisioning in large-scale WRSNs. The insights gained from this study pave the way for future innovations and contribute to the development of sustainable and self-sufficient wireless sensor networks, critical for the advancement of applications such as environmental monitoring, precision agriculture, and smart cities.
International Journal of Manufacturing, Materials, and Mechanical Engineering, 2025
The main objective of reliability-centered maintenance is the cost-effectiveness of the maintenan... more The main objective of reliability-centered maintenance is the cost-effectiveness of the maintenance strategy. These strategies, rather than the different components of reliability-centered maintenance being applied independently, are optimally integrated to take advantage of their respective strengths to optimize equipment reliability and life-cycle costs. The article uses reliability parameters to define the type of maintenance strategy and time to perform maintenance on gas compressors. This article presents a methodology using the gas compressor's reliability parameters to model reliability-centered maintenance procedure for the gas compressors. The approach is based on reliability parameters gotten from the liner regression carried out on the gas compressors. The shape parameter (β) from the Weibull linear regression shows that most components in the two gas compressors were experiencing early failure with their β < 1 and the distribution that best fits the data is the lognormal distribution, whose parameters are the shape parameter (σ') and the scale parameter (µ').
Electronics MDPI, 2024
Food waste is a pressing global issue, particularly in urban settings, where substantial amounts ... more Food waste is a pressing global issue, particularly in urban settings, where substantial amounts of surplus food go unused. In corporate environments, this challenge is compounded by the lack of dedicated platforms to facilitate food sharing and reduce waste effectively. This paper examines the current landscape of food waste, existing solutions, and the need for a specialised platform aimed at corporate employees. The proposed solution is the creation of a user-friendly application that enables the sharing of untouched homemade meals. Suppliers can post their meal boxes with details such as location, type of food, and availability status, while consumers can search for and select meal boxes based on their preferences. This paper addresses the gap in solutions for reducing food waste within corporate environments. The meal-box-sharing app provides a practical and sustainable method for minimising food waste and promoting productivity, health, and safety in the workplace.
Bulletin of Electrical Engineering and Informatics, 2025
Shopping at supermarkets has become a daily activity in urban areas of Enugu, Nigeria. However, t... more Shopping at supermarkets has become a daily activity in urban areas of Enugu, Nigeria. However, there is always a huge rush in most mega supermarkets during times of discount offers, weekends and holidays resulting in long queues due to the barcode billing process. This research proposes a way of reducing the time spent at the billing counter using a radio frequency identification (RFID) smart-based shopping cart. To achieve this objective, an RFID tag, RFID reader, Arduino microcontroller and light-emitting diode (LED) display were used to develop a smart shopping trolley. RFID tag was placed on each of the eight products displayed for sale. RFID reader reads all the products that were placed on the cart and the details of the product such as the name, quantity, cost, and total cost was displayed on the LED. The smart shopping trolley system also incorporates an alarm system that triggers off when the RFID tag is removed from a product to avoid shoplifting and make the system secure for the owners of the supermarket. The result showed that the billing of the products was done directly from the smart shopping cart. The system was compared with the conventional barcode system and was found to overcome the limitations of time-consuming billing procedures.
Engineering Reports, 2024
This article proposes a three‐way (3‐way) equal filtering power divider (FPD) employing the micro... more This article proposes a three‐way (3‐way) equal filtering power divider (FPD) employing the microstrip compact folded‐arms square open‐loop resonator (FASOLR). The proposed FPD evenly distributes an input signal into three equal output signals. The design incorporates balanced signal power division, and filtering technology for the removal of unwanted frequency elements and aimed at enhancing signal quality and efficiency in the radiofrequency (RF) front‐end of communication systems. The use of FASOLR in the design helps to achieve miniaturization by reducing the device footprint. Keysight's Advanced Design System (ADS) software is used for conducting the design simulations. The proposed FPD features a 2.6 GHz center frequency, with a 0.03 fractional bandwidth. The implementation is carried out on Rogers RT/Duroid 6010LM substrate with a dielectric constant of 10.7, a thickness of 1.27 mm, and a loss tangent of 0.0023. This design includes theoretical calculations, circuit modeling, microstrip layout design, and electromagnetic (EM) simulations. The good agreement between the theoretical and practical results verifies the proficiency of the FPD in delivering equal power outputs at the three output ports, and at the same time filtering out unwanted frequencies as required. The practical responses of the prototype FPD indicate a good return loss of better than 15.5 dB and an insertion loss of better than 4.77 + 0.34 dB. The design prototype achieved a compact size of 0.31 × 0.18 λg. The results reinforce the design's competitive edge in performance and actual footprint. λg is the guided wavelength for the microstrip line impedance at the center frequency of the three‐way equal FPD.
International Journal of Manufacturing, Materials, and Mechanical Engineering (IJMMME), 2024
Managing resource allocation for optimum effectiveness at various levels of maintenance activitie... more Managing resource allocation for optimum effectiveness at various levels of maintenance activities is always a challenging task. Optimizing maintenance resources enables an organization to set priorities towards achieving certain goals which are availability and reliability of the equipment for operational excellence. The purpose of this analysis is to determine the optimum resources allocation proportions among the failure modes and to identify the failure modes that have the greatest cumulative effect on the equipment's downtime. This paper presents a methodology using the Pareto analysis in conjunction with failure mode effect and criticality Analysis in maintenance resources optimization. The approach is based on ensuring all failure mode criticality number are considered to obtain the significant failures mode that you should focus on as a priority. The analysis shows that failure mode; FM5, FM 3, FM 2, FM 12, FM 7 and FM 13 are confirmation to the Pareto principle, identifying that most of the downtime of the Instrumentation Air Compressors originated from these failure modes.
Sensors, 2024
5/6G is anticipated to address challenges such as low data speed and high latency in current cell... more 5/6G is anticipated to address challenges such as low data speed and high latency in current cellular networks, particularly as the number of users overwhelms 4G and LTE capabilities. This paper proposes a microstrip patch antenna array comprising six radiating patches and utilizing a microstrip line feeding technique to facilitate the compact design crucial for 5G implementation. ROGER 3003, chosen for its advanced and environmentally friendly features, serves as the dielectric material, ensuring suitability for 5G and B5G applications. The designed antenna, evaluated at a resonating frequency of 28.8 GHz with a −10 dB impedance bandwidth of 1 GHz, offers a high gain of 9.19 dBi. Its compact array, cost-effectiveness, and broad impedance and radiation coverage position it as a viable candidate for 5G and future communication applications.
Frontiers in Mechanical Engineering, 2024
With the increase in demand for high data rates and high bandwidth because of multiple users all ... more With the increase in demand for high data rates and high bandwidth because of multiple users all over the globe, the technology has moved toward the nextgeneration of wireless communication. This rapid advancement of wireless communication technologies has led to the emergence of 5G networks, which promise significantly higher data rates, lower latency, and enhanced connectivity. Researchers believe that five essential techniques can enable 5G. Beamforming is one of those essentials, as it plays a vital role in achieving reliable and high-capacity communication. This review article portrays a comprehensive analysis of the 5G beamformer Microstrip Patch Antenna array techniques for communication systems. The paper comprises of a deep overview of the fundamental concepts and principles of beamforming, including analog, hybrid, and digital beamforming techniques. It explores the advantages and disadvantages of each approach and discusses their suitability for 5G applications. An in-depth examination of various beamforming techniques employed in 5G, encompassing traditional beamforming, massive Multiple-Input-Multiple-Output beamforming, hybrid beamforming, and adaptive beamforming. The discussion encompasses the strengths, weaknesses, and performance trade-offs of each technique, along with their applicability in diverse deployment scenarios and applications. The review of multiple couplers that are used for the feeding of the antenna is discussed with included hybrid coupler, Wilkinson power divider, branch line coupler, and butler matrix in beamformer smart antenna for 5G/6G communications. Numerous beamforming techniques are compared based on their merits, demerits, and applications. Moreover, the dielectric substrate utilized to design the beamformer was also reviewed. The findings presented in this paper serve as a valuable resource for the researcher, scholars, and engineers working in the field of 5G wireless communications and antenna designing, facilitating the development and deployment of efficient and robust beamforming solutions for future 5G networks.
IntechOpen, 2023
Nowadays, the use of power converter technology has expanded into a wide range of low-, medium-, ... more Nowadays, the use of power converter technology has expanded into a wide range of low-, medium-, and high-power applications due to the technology’s capability to efficiently manage electrical energy. In this regard, the high penetration of modern microprocessors capable of implementing high-performance nonlinear digital controllers and the recent advances in the development of high-speed switching power electronic devices, where on-state loss and consequently switching loss of power semiconductors are significantly decreased, have contributed to increased efficiency of the new power converters. As a result, the size of power converters becomes small and the power converters with less heat generation have little environmental stress. Several power converter topologies have been recently proposed in the literature for a variety of emerging applications. These novel converter topologies have different design criteria as well as particularities associated with the digital control system. This book provides a comprehensive overview of the current state of the art and addresses recent breakthroughs in a range of power converter technology, with a special emphasis on design, emerging applications, and control.
Micromachines MDPI, 2023
Folded-arms square open-loop resonator (FASOLR) is a variant of the conventional microstrip squar... more Folded-arms square open-loop resonator (FASOLR) is a variant of the conventional microstrip square open-loop resonator (SOLR) that facilitates further device size miniaturization by having the two arms of the conventional SOLR folded inwards. This paper highlights the benefits of this brand of compact SOLR by implementing a five-pole Chebyshev bandpass filter (BPF) using compact FASOLR. The test BPF is presented, with centre frequency of 2.2 GHz, fractional bandwidth of 10%, passband ripple of 0.04321 dB, and return loss of 20 dB. The design is implemented on a Rogers RT/Duroid 6010LM substrate with a dielectric constant of 10.7 and thickness of 1.27 mm. The filter device is manufactured and characterised, with the experimentation results being used to justify the simulation results. The presented measurement and electromagnetic (EM) simulation results demonstrate a good match. The EM simulation responses achieve a minimum insertion loss of 0.8 dB and a very good channel return loss of 22.6 dB. The measurement results, on the other hand, show a minimum insertion loss of 0.9 dB and a return loss of better than 19.2 dB. The filter component has a footprint of 36.08 mm by 6.74 mm (that is, 0.26 λg x 0.05 λg), with λg indicating the guided wavelength for the 50 Ohm microstrip line impedance at the centre frequency of the proposed fifth-order bandpass filter.
International Journal of Manufacturing, Materials, and Mechanical Engineering, 2022
The degradation of metallic industrial assets, equipment, and components costs governments, indus... more The degradation of metallic industrial assets, equipment, and components costs governments, industries, and citizens billions of dollars a year. Also, the degradation of industrial assets and infrastructure proliferates myriad safety problems. AssessLIFE software addresses this strategic deficiency by focusing on forecasting strategies rather than on mitigation strategies in the active battle against industrial asset degradation. By employing tested and proven scientific analytical computations, forecasting, prediction, and analytics, the AssessLIFE software plans to significantly reduce the billions of dollars expended via inspection, treatment, and repair of degradation-prone assets and infrastructure. The AssessLIFE software leverages many scientific studies and research in many fields of engineering. The AssessLIFE software also emphasizes the computerization or automation of the processes of metallic (alloys and welds) degradation mechanisms and parameters using digital techniques.
Electronics MDPI, 2022
Substrate-integrated waveguide (SIW) is a modern day (21st century) transmission line that has re... more Substrate-integrated waveguide (SIW) is a modern day (21st century) transmission line that has recently been developed. This technology has introduced new possibilities to the design of efficient circuits and components operating in the radio frequency (RF) and microwave frequency spectrum. Microstrip components are very good for low frequency applications but are ineffective at extreme frequencies, and involve rigorous fabrication concessions in the implementation of RF, microwave, and millimeter-wave components. This is due to wavelengths being short at higher frequencies. Waveguide devices, on the other hand, are ideal for higher frequency systems, but are very costly, hard to fabricate, and challenging to integrate with planar components in the neighborhood. SIW connects the gap that existed between conventional air-filled rectangular waveguide and planar transmission line technologies including the microstrip. This study explores the current advance-ments and new opportunities in SIW implementation of RF and microwave devices including filters, multiplexers (diplexers and triplexers), power dividers/combiners, antennas, and sensors for modern communication systems.
Bulletin of Electrical Engineering and Informatics, 2021
Owing to recent technological advancement, computers and other devices running several image edit... more Owing to recent technological advancement, computers and other devices running several image editing applications can be further exploited for digital image processing operations. This paper evaluates various image processing techniques using matrix laboratory (MATLAB-based analytics). Compared to the conventional techniques, MATLAB gives several advantages for image processing. MATLAB-based technique provides easy debugging with extensive data analysis and visualization, easy implementation and algorithmic-testing without recompilation. Besides, MATLAB's computational codes can be enhanced and exploited to process and create simulations of both still and video images. Moreover, MATLAB codes are much concise compared to c++, thus making it easier for perusing and troubleshooting. MATLAB can handle errors prior to execution by proposing various ways to make the codes faster. The proposed technique enables advanced image processing operations such as image cropping/resizing, image denoising, blur removal, and image sharpening. The study aims at providing readers with the most recent MATLAB-based image processing application-tools. We also provide an empirical-based method using two-dimensional discrete cosine transform (2D-DCT) derived from its coefficients. Using the most recent algorithms running on MATLAB toolbox, we performed simulations to evaluate the performance of our proposed technique. The results largely present MATLAB as a veritable approach for image processing operations.
International Journal of Electronics, Communications, and Measurement Engineering, 2021
Electronics MDPI, 2021
A compact unbalanced two-way filtering power splitter with an integrated Chebyshev filtering func... more A compact unbalanced two-way filtering power splitter with an integrated Chebyshev filtering function is presented. The design is purely based on formulations, thereby eliminating the constant need for developing complex optimization algorithms and tuning, to deliver the desired amount of power at each of the two output ports. To achieve miniaturization, a common square open-loop resonator (SOLR) is used to distribute energy between the two integrated channel filters. In addition to distributing energy, the common resonator also contributes one pole to each integrated channel filter, hence, reducing the number of individual resonating elements used in achieving the integrated filtering power splitter (FPS). To demonstrate the proposed design technique, a prototype FPS centered at 2.6 GHz with a 3 dB fractional bandwidth of 3% is designed and simulated. The circuit model and layout results show good performances of high selectivity, less than 1.7 dB insertion loss, and better than 16 dB in-band return loss. The common microstrip SOLR and the microstrip hairpin resonators used in implementing the proposed integrated FPS ensures that an overall compact size of 0.34 λg × 0.11 λg was achieved, where λg is the guided-wavelength of the 50 Ω microstrip line at the fundamental resonant frequency of the FPS passband.
Indonesian Journal of Electrical Engineering and Informatics, 2020
This paper presents a step-by-step approach to the design of bandpass/channel filters. A 3-pole C... more This paper presents a step-by-step approach to the design of bandpass/channel filters. A 3-pole Chebyshev bandpass filter (BPF) with centre frequency of 2.6 GHz, fractional bandwidth of 3%, passband ripple of 0.04321 dB and return loss of 20 dB has been designed, implemented, and simulated. The designed filter implementation is based on the Rogers RT/Duroid 6010LM substrate with a 10.7 dielectric constant and 1.27 mm thickness. The BPF was also fabricated using the same substrate material used for the design simulation. The circuit model and microstrip layout results of the BPF are presented and show good agreement. The microstrip layout simulation results show that a less than 1.8 dB minimum insertion loss and a greater than 25 dB in-band return loss were achieved. The overall device size of the BPF is 18.0 mm by 10.7 mm, which is equivalent to 0.16λg x 0.09λg, where λg is the guided wavelength of the 50 Ohm microstrip line at the filter centre frequency.
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Papers by Augustine O. Nwajana, PhD, FHEA, SMIEEE