In this paper, the low-loss coaxial probe fed microwave cavity filter is presented. The filter ha... more In this paper, the low-loss coaxial probe fed microwave cavity filter is presented. The filter has recently shown great performance improvement in its selectivity and S-parameter response, but the rate of signal to noise ratio due to spurious modes in the pass band is significantly too high to ignore. A 2nd order band pass filter is investigated and its S-parameter response analysed by employing improved dielectric-loaded cavity resonators. The design is based on a low pass Chebyshev prototype at 1 dB insertion loss and 10 dB return loss. An efficient analytical method for reducing the spurious bandwidth of the filter is also devised to improve the filter response. The results shows that the filter, on its single mode operation state, provides increased selectivity and a significant amount of Q values are achieved to reduce the transmission losses.
Advances in mobile technology, due to the rapid growth of mobile wireless systems, coupled with s... more Advances in mobile technology, due to the rapid growth of mobile wireless systems, coupled with stringent selectivity requirements, have led to the need for smaller and lighter high quality filters. The slotted cylindrical ring resonator is one resonator considered promising in the development of high quality compact filters for mobile communication systems due to its small size and medium to high Q-factor [1]. In this paper the Transmission Line Modeling method is used to determine the effects of using a high dielectric constant material on the size and coupling constant of the resonator. Modeling and simulations are done using Microstripes, a commercial TLM field solver from Flomerics. The paper shows that by placing a high dielectric constant material in the resonator gap the resonant size is decreased and the coupling improved. Keywords: Slotted cylindrical ring resonator, resonant frequency, electric coupling, magnetic coupling, Transmission line modeling
2017 IEEE Radio and Antenna Days of the Indian Ocean (RADIO), 2017
The effect of thickness of a hollow post in a combline resonator on the resonant frequency, coupl... more The effect of thickness of a hollow post in a combline resonator on the resonant frequency, coupling coefficients and spurious performance are analysed. It is shown that both the electric and magnetic couplings are not significantly affected by the size of the thickness of the hollow post, whereas the resonant frequency and spurious free band both change. When the thickness of the hollow post reduces the spurious free band deteriorates while the resonant frequency increases.
IoT opportunities and application domains are endless and equally have shortcomings that need to ... more IoT opportunities and application domains are endless and equally have shortcomings that need to be addressed. This section broadens the open research areas that need to be further investigated to address the challenges in IoT networks. We highlight potential future directions and futuristic applications that can help alleviate these challenges. Although the application of IoT has been widely adopted, an extensive research effort still needs to be done in this direction. This chapter aims to further discuss and collate future work direction in the area of IoT sensor networks to give insights to researchers for areas that still need investigation in wireless IoT sensor networks. Open research areas in IoT sensor networks include hardware security, lack of lightweight cryptographic algorithms, lack of trust management systems, lack of lightweight, secure routing protocols, and anti-malware solutions. Future challenges have been exposed in this chapter, with the hope of encouraging fur...
The proliferation of the Internet has birthed the emergence of the Internet of Things (IoT), whic... more The proliferation of the Internet has birthed the emergence of the Internet of Things (IoT), which is rapidly evolving and already taking strides as a universal solution to connected things. IoT transforms devices to be smart, to deliver exceptional services, and to transform everyday settings. The rapid evolution of IoT has brought along many benefits. However, IoT has also brought about ambiguity and several security concerns to IoT adopters. Security issues are the most critical challenges that need to be addressed in promoting the adoption and development of IoT systems. Addressing these challenges using a layered approach has not been adequately addressed. Several studies have proposed solutions to address security issues. Nevertheless, they have failed to propose an appropriate layered security approach or framework that addresses the majority of the security issues using a cross-layered approach. The aim of this work is to highlight security issues and challenges and provide ...
Due to the advances in technology, growth of IoT, and the numerous advantages that come with havi... more Due to the advances in technology, growth of IoT, and the numerous advantages that come with having connected devices, almost any device can be made into a smart IoT device, even a simple day-to-day home appliance. Limitations of what can be made into a smart IoT device are based on the cost and practicality of the device. Examples of smart IoT devices that can be found in a building include smart light bulbs, smart kettles, smart switches, smart refrigerators, and many more. In this chapter, we report on the design and implementation of smart IoT devices and applications through the solving of an example problem of adding security and access control to a building’s main electricity. Through this chapter, one will become familiar with the design process of making smart IoT devices. Each section in this chapter shows the methods and procedures undertaken to design the smart IoT devices used to solve the given example problem. This includes the problem definition, aim, and objectives....
In this paper, the low-loss coaxial probe fed microwave cavity filter is presented. The filter ha... more In this paper, the low-loss coaxial probe fed microwave cavity filter is presented. The filter has recently shown great performance improvement in its selectivity and S-parameter response, but the rate of signal to noise ratio due to spurious modes in the pass band is significantly too high to ignore. A 2nd order band pass filter is investigated and its S-parameter response analysed by employing improved dielectric-loaded cavity resonators. The design is based on a low pass Chebyshev prototype at 1 dB insertion loss and 10 dB return loss. An efficient analytical method for reducing the spurious bandwidth of the filter is also devised to improve the filter response. The results shows that the filter, on its single mode operation state, provides increased selectivity and a significant amount of Q values are achieved to reduce the transmission losses.
Advances in mobile technology, due to the rapid growth of mobile wireless systems, coupled with s... more Advances in mobile technology, due to the rapid growth of mobile wireless systems, coupled with stringent selectivity requirements, have led to the need for smaller and lighter high quality filters. The slotted cylindrical ring resonator is one resonator considered promising in the development of high quality compact filters for mobile communication systems due to its small size and medium to high Q-factor [1]. In this paper the Transmission Line Modeling method is used to determine the effects of using a high dielectric constant material on the size and coupling constant of the resonator. Modeling and simulations are done using Microstripes, a commercial TLM field solver from Flomerics. The paper shows that by placing a high dielectric constant material in the resonator gap the resonant size is decreased and the coupling improved. Keywords: Slotted cylindrical ring resonator, resonant frequency, electric coupling, magnetic coupling, Transmission line modeling
2017 IEEE Radio and Antenna Days of the Indian Ocean (RADIO), 2017
The effect of thickness of a hollow post in a combline resonator on the resonant frequency, coupl... more The effect of thickness of a hollow post in a combline resonator on the resonant frequency, coupling coefficients and spurious performance are analysed. It is shown that both the electric and magnetic couplings are not significantly affected by the size of the thickness of the hollow post, whereas the resonant frequency and spurious free band both change. When the thickness of the hollow post reduces the spurious free band deteriorates while the resonant frequency increases.
IoT opportunities and application domains are endless and equally have shortcomings that need to ... more IoT opportunities and application domains are endless and equally have shortcomings that need to be addressed. This section broadens the open research areas that need to be further investigated to address the challenges in IoT networks. We highlight potential future directions and futuristic applications that can help alleviate these challenges. Although the application of IoT has been widely adopted, an extensive research effort still needs to be done in this direction. This chapter aims to further discuss and collate future work direction in the area of IoT sensor networks to give insights to researchers for areas that still need investigation in wireless IoT sensor networks. Open research areas in IoT sensor networks include hardware security, lack of lightweight cryptographic algorithms, lack of trust management systems, lack of lightweight, secure routing protocols, and anti-malware solutions. Future challenges have been exposed in this chapter, with the hope of encouraging fur...
The proliferation of the Internet has birthed the emergence of the Internet of Things (IoT), whic... more The proliferation of the Internet has birthed the emergence of the Internet of Things (IoT), which is rapidly evolving and already taking strides as a universal solution to connected things. IoT transforms devices to be smart, to deliver exceptional services, and to transform everyday settings. The rapid evolution of IoT has brought along many benefits. However, IoT has also brought about ambiguity and several security concerns to IoT adopters. Security issues are the most critical challenges that need to be addressed in promoting the adoption and development of IoT systems. Addressing these challenges using a layered approach has not been adequately addressed. Several studies have proposed solutions to address security issues. Nevertheless, they have failed to propose an appropriate layered security approach or framework that addresses the majority of the security issues using a cross-layered approach. The aim of this work is to highlight security issues and challenges and provide ...
Due to the advances in technology, growth of IoT, and the numerous advantages that come with havi... more Due to the advances in technology, growth of IoT, and the numerous advantages that come with having connected devices, almost any device can be made into a smart IoT device, even a simple day-to-day home appliance. Limitations of what can be made into a smart IoT device are based on the cost and practicality of the device. Examples of smart IoT devices that can be found in a building include smart light bulbs, smart kettles, smart switches, smart refrigerators, and many more. In this chapter, we report on the design and implementation of smart IoT devices and applications through the solving of an example problem of adding security and access control to a building’s main electricity. Through this chapter, one will become familiar with the design process of making smart IoT devices. Each section in this chapter shows the methods and procedures undertaken to design the smart IoT devices used to solve the given example problem. This includes the problem definition, aim, and objectives....
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Papers by Joseph Chuma