Ahmad Asari Sulaiman

A Novel 5.8 GHz High Gain Array Dielectric Resonator Antenna

In this paper, a novel nine elements array dielectric resonator antenna (DRA) is presented. The DRA was excited by a microstrip feeder with a rectangular aperture coupled slots. The slot positions were determined based on the characteristic of standing wave ratio over a short ended microstrip. The measured gain of the array DRA operating at 5.84 GHz was about 10 dBi having impedance bandwidth of 60MHz. The proposed DRA exhibits an enhancement of the gain in comparison with a single pellet DRA. The size of the whole antenna structure is about 60 mm× 40mm and potentially can be used in wireless systems.

Circular patch antenna on metamaterial

This paper recommends a compact circular antenna on metamaterial substrate for C-band applications. The antenna has been designed to improve the performance of gain directivity, return loss and size. The size of the new metamaterial antenna has been reduced by a factor of 2.4 and the gain directivity was increased from 4.17 dBi in conventional design on Flame Retardant 4 (FR-4) to 5.66 dBi in the new approach. A better return loss was obtained from the metamaterial antenna which is −24.2 dB compared to −22.08 from the conventional antenna. By analyzing the radiation pattern, the metamaterial antenna has a sharp focus to the targeted direction. The compact antenna is expected to improve the cost of production due to the size reduction in a mess production.

Performance analysis for Estimation of signal Parameters via Rotational Invariance Technique (ESPRIT) in estimating Direction of Arrival for linear array antenna

Smart antenna refers to any type of antenna arrays combined with signal processor components which can adjust its own beam pattern in order to emphasize on the signal of interest and minimizing the interference signal. The accurate estimation of direction of interest which is also known as direction of arrival (DOA) of the incident signals is very significant to produce beam from antenna. There are several algorithms those have the ability in calculating the DOA of the incidents signals. In this paper an adaptive antenna is applied by using the most frequent used algorithm, estimation of signal parameters via rotational invariance technique (ESPRIT) to obtain the direction of arrival (DOA) of any incident signals. The exact number of samples and elements used is the most important parameter in the algorithms in order to sustain the accuracy of the direction of arrival of the incident signals. The optimization was done by running the program in cellular mobile environments. The data from the optimization was evaluated using SPSS in evaluating the performance of the algorithm.

Enhancement of bandwidth through I-shaped Defected Ground Structure

This paper discuss on a rectangular microstrip patch antenna incorporated with I-shaped Defected Ground Structure (DGS) metamaterial which exhibit an enhancement of 118% bandwidth compared to the conventional design. The antenna is designed for S-band application, resonates at 2.45 GHz. The I-shaped DGS shows the metamaterial characteristics with negative permeability, μ and permittivity, ε through Nicolson-Ross-Weir method. The circuit was designed using Computer Simulation Technology (CST) Microwave Studio. Based on the simulation, the antenna also shows other improvement in term of gain and return loss of 17.6% and 71.89%, respectively. The Size of the radiating patch was also reduced for about 21% The performance of the fabricated antenna such as antenna gain, return loss, bandwidth and directivity were also measured using the Vector Network Analyzer (VNA) for a verification.

X-Band dielectric resonator bandpass filter

This paper presents a new approach of designing a bandpass filter by applying a combination of microstrip and cylindrical shape of dielectric resonators for X-Band application. Three dielectric resonators with a same permittivity and diameter of 60 and 5 mm respectively are applied in the circuit in order to obtain a wideband of more than 1.0 GHz. The interaction between the microstrip transmission line and dielectric resonators increases the coupling effect as well as minimizing the insertion loss in the filter passband. An analysis on the effect of the height of the dielectric resonators has been investigated in order to prove that the new approach contributes more advantages and viable at the desired application band.

Earthquake prediction technique based on GPS dual frequency system in equatorial region

The ionospheric Total Electron Content (TEC) measurements were investigated at Universiti Teknologi Malaysia, UTMJ on 20 February - 20 March 2007. The observation was made 14 days before earthquake and 14 days after earthquake. TEC is extracted using GPS dual frequency data which in RINEX format that supplied by JUPEM (Jabatan Ukur dan Pemetaaan Malaysia). In order to reveal possible earthquake precursor through the changes variation of TEC reading, Southern Sumatra Indonesia earthquake that happened on 6th March 2007 is chosen as a study case. The results show that satellite facilities may detect earthquake precursors in ionosphere 5-11 days or a few hours before main shock and various grounds based or satellite observation have shown strong perturbation of the ionosphere after earthquake. The results show a good agreement with other researchers who studied other earthquakes.

Electromagnetic simulation of the effects of dielectric and metal thicknesses on the performance of multilayer MMIC lowpass filter

The authors report on the effects of dielectric and metal thicknesses on the performance of a multilayer monolithic microwave integrated circuit (MMIC) lowpass filter. An electromagnetic simulator, Sonnet, is used to characterize and predict the effect of both factors on the filter response. Results of this simulation show that the filter operates with optimum performance when the metal and polyimide thicknesses are 5 /spl mu/m each.

Wi-Fi and GSM Based Motion Sensor for Home Security System Apllication

The Wi-Fi and GSM based home security system is a system designed to reduce the high rates of crimes in most personal housing. The overall project consists of three major parts; the input part that consists of sensors, the software part that operates the entire hardware structure, and the output part, which consists of camera, alarm system, and micro secure digital (SD) data storage card. It is based on the principle of infrared radiation generated by a human body heat which trigger the passive infrared (PIR) sensor. The microcontroller processes the received signal, then trigger the buzzer alarm, camera and alerts the home owner through an SMS. Once triggered, the camera will capture the image of the intruder and the image will be saved in SD card. As alert to the user (away), the Global System for Mobile Communication (GSM) will send the Short Message Service (SMS) from the device to the users mobile phone. The image will be sent to Dropbox data cloud storage via Wi-Fi for further clarification. The prototype was successfully developed, tested and has been installed at residential area in Taman Cahaya Alam, Section U12, Shah Alam, Malaysia.

Radio frequency radiation at satellite earth station for occupational safety and health

This paper presents on Radio Frequency (RF) Radiation at Satellite Earth Station and the effect to occupational workers and members of the public. This research and measurement was requested by OSH Committee, Satellite Earth Station, Telekom Malaysia Berhad as a result of concern raised by their workers and member of the public about potential health hazard caused by the RF radiation emitted by the Satellite Earth Station. This study shall produce the Radio Frequency radiation strength at Satellite Earth Station and the measurement will include the electric field strength, magnetic field strength and power density at certain identified locations at the Satellite Earth Station. In general, results of the research indicate that the radio frequency radiation present in the Satellite Earth Station were measurable but of very low levels. The result of the measured radiations is evaluated based on the exposure limits and the recommendations set by Malaysian Communications and Multimedia Commission (MCMC) and International Commissionon Non-Ionizing Radiation Protection (ICNIRP) for occupational workers and members of the public. Based on the evidences presented, the researcher is convinced that the health hazard is minimized and the radio frequency radiation at Satellite Earth Station has no adverse effect to the health, and the claim done by workers and member of the public at the Satellite Earth Station is unfounded and baseless.

Accident reporting system using an iOS application

This paper presents on development of an accident reporting system using an iOS application. Normally, accidents at workplace could only be reported on a standard paper form but there are often delays in submitting the reports, as well as difficulties in retrieving them back for analyzing purposes. Additionally, reporting via paper format consumes paper resources, which is not environmental friendly. The iOS accident reporting system application was developed using Xcode SDK 5.1, focusing on device with iOS 7 as their operating system. The mobile application allows user with iOS devices such as iPhone or iPad, to report occupational accidents, quickly. The report is sent email to the Safety and Health Officer. Hence, this application makes accident reporting task become more efficient and effective, for immediate action to be taken.