Enhanced Antenna Design for Rectenna Application in the 2.45 GHz ISM Band

In this paper a two layers microstrip antenna design at 2.45 GHz ISM band with Harmonic rejection filter embedded on the ground plane is presented. The two roger substrates with relative permittivity of 2.2 are separated by an air gap which enhances the antenna gain. The design is simulated using Computer Simulation Technology (CST) Studio Suite 2015. Different aperture couplings slots such as rectangular and triangular aperture coupling slots are studied and compared. It is found that the antenna with triangular aperture coupling slot enhances the antenna performance by suppressing 2nd and 3rd harmonics at 5 GHz and 8 GHz, respectively, increasing the antenna gain and providing a better circular polarization behavior. The simulated antenna design achieves a gain of 9 dB, return loss of -23.6dB, axial ratio of 1.27dB and axial-ratio bandwidth of 40.8% (2 ~ 3 GHz). The proposed antenna shows an enhancement in the antenna performance which makes it a suitable candidate for rectifying antenna or rectenna application as it can increase the total conversion efficiency resulting in a high output DC voltage used to power low power electronic and electrical devices such as wireless sensor

A Systematic Review of User Mental Models on Applications Sustainability

In Human-Computer Interaction (HCI), a user’s mental model affects application sustainability. This study's goal is to find and assess previous work in the area of user mental models and how it relates to the sustainability of application. Thus, a systematic review process was used to identify 641 initial articles, which were then screened based on inclusion and exclusion criteria. According to the review, it has been observed that the mental model of a user has an impact on the creation of applications not only within the domain of Human-Computer Interaction (HCI), but also in other domains such as Enterprise Innovation Ecology, Explainable Artificial Intelligence (XAI), Information Systems (IS), and various others. The examined articles discussed company managers' difficulties in prioritising innovation and ecology, and the necessity to understand users' mental models to build and evaluate intelligent systems. The reviewed articles mostly used experimental, questionnaire, observation, and interviews, by applying either qualitative, quantitative, or mixed-method methodologies. This study highlights the importance of user mental models in application sustainability, where developers may create apps that suit user demands, fit with cognitive psychology principles, and improve human-AI collaboration by understanding user mental models. This study also emphasises the importance of user mental models in the long-term viability and sustainability of applications, and provides significant insights for application developers and researchers in building more user-centric and sustainable applications

Design of Low Cost Greenhouse Monitoring using ZigBee Technology

Greenhouses are often used for growing flowers, vegetables, fruits, and tobacco plants. Most greenhouse systems still use the manual system in monitoring the temperature and humidity in the greenhouse, a lot of problems can occur not for worker but also affected production rate because the temperature and humidity of the greenhouse must be constantly monitored to ensure optimal conditions. The Wireless Sensor Network (WSN) can be used to gather the data from point to point to trace down the local climate parameters in different parts of the big greenhouse to make the greenhouse automation system work properly. This paper presents the design of low cost greenhouse monitoring system to monitor a greenhouse temperature and humidity parameters by applying the ZigBee technology as the WSN system. During the design process, Peripheral Interface Controller (PIC), LCD Display and Zigbee as the main hardware components is used as hardware components while C compiler and MP Lab IDE were used for software elements. The data from the greenhouse was measured by the sensor then the data will be displayed on the LCD screen on the receiver which support up to 100 m range. By using this system, the process of monitoring is easier and it also cheaper for installation and maintenance. The feasibility of the developed node was tested by deploying a simple sensor network into the Agriculture Department of Melaka Tengah greenhouse in Malaysia

Design of Low Power Wideband Low Noise Amplifier for Software Defined Radio at 100 MHz to 1 GHz

This paper describes the design of wideband low noise amplifier (LNA) for mobile software defined radio (SDR) application which targeted to be applied in two-way communication mobile system architecture. The technical specification was deduced from the TIA- 603C standard receiver system sensitivity and intermodulation. The proposed LNA exhibit low power consumption and adopts a negative feedback wideband amplifier topology, operated from 100 MHz to 1 GHz which covers the whole Land Mobile FM Communication Equipment (136 941 MHz) frequency band. The proposed topology solve the RF tracing problem inherited in the targeted frequency and also the problem of economically impractical PCB size rendered by other wideband amplifier methods. The Advanced Design System software is used to perform the simulations. The measured result show the proposed LNA has a stable gain of more than 15 dB, noise figure less than 1.5 dB, S11 and S22 less than -10 dB, with current consumption of 8 mA from voltage supply at 1.8 V

Development of Greenhouse Monitoring using Wireless Sensor Network through ZigBee Technology

Greenhouses are often used for growing flowers, vegetables, fruits, and tobacco plants. Most greenhouse systems still use the manual system in monitoring the temperature and humidity in the greenhouse, a lot of problems can occur not for worker but also affected production rate because the temperature and humidity of the greenhouse must be constantly monitored to ensure optimal conditions. The Wireless Sensor Network (WSN) can be used to gather the data from point to point to trace down the local climate parameters in different parts of the big greenhouse to make the greenhouse automation system work properly. This paper presents the design of low cost greenhouse monitoring system to monitor a greenhouse temperature and humidity parameters by applying the ZigBee technology as the WSN system. During the design process, Peripheral Interface Controller (PIC), LCD Display and Zigbee as the main hardware components is used as hardware components while C compiler and MP Lab IDE were used for software elements. The data from the greenhouse was measured by the sensor then the data will be displayed on the LCD screen on the receiver which support up to 100 m range. By using this system, the process of monitoring is easier and it also cheaper for installation and maintenance. The feasibility of the developed node was tested by deploying a simple sensor network into the Agriculture Department of Melaka Tengah greenhouse in Malaysia

Field evaluation of the efficacy of the mosquito killing system

A preliminary field study was undertaken to evaluate the efficacy of a mosquito trap; Mosquito Killing System (MKS) in capturing mosquitoes and other insects. MKS has an automatic activation by the use of a photocell. It is also supplemented with carbon dioxide and heat as attractants for mosquitoes and other insects. Three units of MKS were employed at three different locations within two study sites for ten days. The mosquitoes and other insects that were trapped in MKS were collected and morphologically identified daily in the laboratory. A total of 1,928 mosquitoes and other insects were trapped in all units of MKS. High numbers of mosquitoes (93.05%), particularly Aedes sp. and Culex sp. were captured from MKS. Among these, Culex quinquefasciatus (91.81%) was most abundant species collected. Only 0.84% of Aedes aegypti and Aedes albopictus trapped in MKS. Female mosquitoes (83.44%) were found to be more attracted to MKS compared to male mosquitoes of various species. These findings illustrated the potency of MKS utilization in surveillance and control activities of Cx. quinquefasciatus; a nuisance mosquito and also potential vector of urban brancroftian filariasis in Malaysia

Design of Low Noise Amplifier for Radio over Fiber at 5.2 GHz

This paper presents the design and simulation of low noise amplifier (LNA) used in an active radio access point (RAP) for Radio over Fiber (RoF) technology at 5.2 GHz. RoF is integration of optical fiber for radio signal transmission within network infrastructures that is considered to be cost effective, practical and relative system configuration for long haul transport of millimeter frequency band wireless signal. The LNA designed function is to amplify extremely low signals without adding noise, thus preserving the required Signal Noise Ratio (SNR) of system at extremely low power signal. The implementation of design is based on Agilent ATF-5143 transistor and Microwave Office software is used to perform the simulation in S-parameters. The design and simulation process including selecting the transistor based on RoF requirements, stability of transistor, matching network, biasing and optimization. The design has shown an acceptable behavior with gain of 16.046 dB and noise figure of 0.9368 dB using conjugate matching method

Design of Wideband Low Noise Amplifier using Negative Feedback Topology for Motorola Application

This paper describes the design of wideband low noise amplifier (LNA) for Motorola application which targeted to be applied in two-way communication mobile system architecture. The technical specification was deduced from the TIA-603C standard receiver system sensitivity and inter-modulation. The proposed LNA exhibit low power consumption and adopts a negative feedback wideband amplifier topology, operated from 100 MHz to 1 GHz which covers the whole Land Mobile FM Communication Equipment (136 – 941 MHz) frequency band. The proposed topology solve the RF tracing problem inherited in the targeted frequency and also the problem of economically impractical PCB size rendered by other wideband amplifier methods. The Advanced Design System software is used to perform the simulations. The measured result show the proposed LNA using FR4 board has a stable gain of more than 15 dB, noise figure less than 1.5 dB, S11 and S22 less than -10 dB, with current consumption of 8 mA from voltage supply at 1.8 V

Development of microwave brain stroke imaging system using multiple antipodal vivaldi antennas based on Raspberry Pi technology

This paper proposes a Microwave Imaging System (MIS) for brain stroke detection. In the MIS, the primary challenge is to improve in terms of cost, size, and stroke image quality. Thus, the main contribution of this work is the economy and the compact rotation platform integrated with an array of nine antipodal Vivaldi antenna in circular arrangement and single computer board, Raspberry Pi Module (RPM) as microcontroller developed. The design and fabrication of wideband antenna based on Computer Simulation Technology (CST) software and Rogers RO4350B substrate, which operated from 2.06 GHz to 2.61 GHz. In the RPM, the Python programming language used for regulating the angle of rotation and antenna switching process. The process of receiving reflection signals from the head phantom for each antenna supervised by Single-Pole 8-Throw (SP8T) Radio Frequency (RF) switch. The fabricated head phantom based on the primary tissues of the brain, white matter using inexpensive materials, and located in the middle of the platform. Platform rotation is a combination of wood-based platform with the size 0.36m2 and material Perspex. Then, through an interfacing process between Python script and Vector Network Analyzer (VNA), the raw data in S-Parameters transferred to the MATLAB software for analysis. The fabricated antenna able to realize high directivity, 86.92% efficiency, and 2.45 dBi gain. Overall, the proposed system offers the cost-effective, compact, and able to collect the data effectively around the head phantom that consist of a target clot and without a target clot at 50 different positions. It successfully tracked the presence of stroke clots through color differences in color plots

Simulation of 2.4 GHz Low Power RF Front End Design for Radio over Fiber Technology

This paper presents the simulation low power RF front end design of radio access point (RAP) for Radio over Fiber (RoF) technology at 2.4 GHz. Wireless network based on radio over fiber (RoF) technology has been proposed as a promising cost effective solution to meet ever increasing user bandwidth and wireless demands. In this network, a central station (CS) is connected to numerous functionally simple radio access point (RAP) via an optical fiber.The only components required at the passive RAP are Electro Absorption Modulator (EAM) and antenna where EAM is used as a remote transceiver. Pico cell has a coverage range up to 100 m. To achieve this distance, RAP needs to operate in active mode, by inserting RF power amplifier and Bandpass Filter (BPF) between EAM and the antenna for the downlink path. BPF is needed remove out of band interference after EAM while the power amplifier is used to improve the dynamic range of RAP. The implementation of the design is based on microstrip technology and Advanced Design System (ADS) software used to perform the simulation. In the simulation, the analyses of scattering parameters are concerned which presents the gain and return loss of the front end. At the end of design, the combination between parallel couple BPF and power amplifier is purposed as a RF front end of RAP for RoF technology