Showing papers by "Norbahiah Misran published in 2012"

Design analysis of new metamaterial for EM absorption reduction

Abstract: A new triangular metamaterials (TMMs) is designed for electromagnetic (EM) absorption reduction at microwave frequencies in this paper. The reduction of EM absorption with a new TMMs attachment is investigated in this research. The flnite-difierence time-domain method with lossy-Drude model is adopted in this investigation. The method of EM reduction is presented and the efiects of position, distance, and size of metamaterials are analyzed. TMMs have achieved a 1.0923W/kg for SAR 1gm which is 45.44% reduction of the initial SAR value for the case of 1gm SAR.

A Novel Compact Split Ring Slotted Electromagnetic Bandgap Structure for Microstrip Patch Antenna Performance Enhancement

Abstract: A novel design of an electromagnetic bandgap (EBG) structure based on the uniplanar compact EBG (UCEBG) concept is proposed in this paper. The structure is realized by inserting split- ring slots inside two reversely connected rectangular patches, which is known as a split-ring slotted electromagnetic bandgap (SRS-EBG) structure. The bandgap properties of the EBG structure are examined by the suspended microstrip line and flnite element methods (FEM). The achieved bandgaps have widths of 4.3 (59.31%) and 5.16GHz (38.88%), which are centered at 7 and 13GHz, respectively. The SRS-EBG is applied to enhance the performance of a single-element microstrip patch antenna (at 7GHz) and a two-element array (at 13GHz) conflguration. A wider bandwidth is obtained with a better re∞ection coe-cient level for the single element antenna; a reduction in mutual coupling of more than 20.57dB is obtained for the array design. In both cases, the gain and radiation characteristics are improved. The results are verifled by measuring the fabricated lab prototype, and a comparison with the computed results showed good agreement.

Curve Fitting Based Particle Swarm Optimization for UWB Patch Antenna

Abstract: An optimization technique for microstrip patch antenna using Curve Fitting based Particle Swarm Optimization (CFPSO) is presented in this paper. An E-H shaped patch antenna designed using conventional optimization technique for Ultra Wide Band (UWB) communication is utilized to demonstrate the optimization technique. The conventional optimized antenna is designed by searching an acceptable solution from amongst the invariably huge collective range of geometry variables. The data for curve fitting is obtained from EM simulator by varying different geometrical parameters of the antenna. Using the data, the equations representing the relationship among different parameters of a microstrip antenna are generated. Curve fitting software was used to generate the curve. The CFPSO program was developed and executed in MATLAB. Conventionally optimized antenna is compared with CFPSO optimized antenna in this paper. The result yields that CFPSO showed remarkable improvement over bandwidth. For the E-H shaped antenna,...

Analysis of Materials Effects on Radio Frequency Electromagnetic Fields in Human Head

Abstract: In this paper, we propose to study the variability of speciflc absorption rate (SAR) of a human head due to difierent materials in the vicinity of the handset. We include the efiects of the human hand, handset chassis and additional conductive material particularly hand- ring jewelry. A flnite-difierence time-Domain (FDTD) method was used to analyze difierent positions of the conductive ring materials within the hand model. Furthermore, the impact of this material on the performance of an antenna was considered in this study. We found that including a hand model leads to a signiflcant reduction in SAR. The hand in∞uences not only SAR distribution but also antenna performance. Moreover, adding conductive materials to the hand results in increases in the local SAR values of the head model. The results suggest that the hand model is important in SAR evaluation and that having an additional conductive material on the hand may vary the amount of electromagnetic (EM) energy absorption depending on the position of the material.

A Compact Wideband Antenna on Dielectric Material Substrate for K Band

Abstract: A wideband modified S shaped electrically small microstrip patch antenna on Aluminium tri-oxide ceramic substrate is designed and analyzed in this paper. The proposed microstrip line fed miniature patch antenna designed by using high frequency electromagnetic solver and the computed results are analyzed by using finite element method. It is observed from the obtained results that, 830 MHz bandwidth (Return loss <-10dB), 2dBi average gain, 97.33% of average efficiency are achieved in the operating frequency from 19.97 GHz to 20.80 GHz for K band satellite applications. Furthermore, the co-cross polarization of the radiation pattern and the current distribution for E-H field is analyzed. Ill. 6, bibl. 18, tabl. 1 (in English; abstracts in English and Lithuanian). DOI: http://dx.doi.org/10.5755/j01.eee.123.7.2378

A three-stacked patch antenna using high-dielectric ceramic material substrate

Abstract: The design and analysis of a new three-stacked patch antenna on aluminum oxide ceramic material substrate are presented in this article Using high-dielectric material substrate, the overall size of the antenna is appreciably reduced without compromising the performance result of the antenna The proposed antenna is designed and studied using commercially available finite element method–based high-frequency electromagnetic solver from ANSYS Corporation From the result, it is observed that in the operating frequency range from 1620 to 1931 GHz (voltage standing wave ratio < 2), a wide range of bandwidth of 309 GHz and gain of 705 dBi at a resonant frequency of 1720 GHz is achieved It is also found that at the entire operating frequency band, the average gain is 35 dBi and the radiation efficiency is from 84% to 89% The proposed antenna is fit for part of Ku-band and Ka-band applications

A compact wideband coplanar waveguide fed metamaterial-inspired patch antenna for wireless application

Abstract: A metamaterial-inspired compact patch antenna resonating between 2 and 6.3 GHz for various wireless standards is proposed. The antenna is a patch antenna that is loaded with a metamaterial-inspired loading structure and is fed using a coplanar waveguide feed line that has been designed to have a characteristic impedance of 50 Ω. The compact antenna is a wideband antenna with a bandwidth (below −10 dB) of 4.3 GHz. The size of the patch in terms of the free-space wavelength at the lowest resonance frequency is λ 0/11×λ 0/7×λ 0/90. The large bandwidth of the antenna is obtained by loading a conventional patch antenna with a metamaterial-inspired loading structure that has been designed to resonate at its lowest fundamental left-handed mode, near to the conventional patch’s resonant frequency.

Effects of Dielectric Values and Substrate Materials on Electromagnetic (EM) Absorption in Human Head

Abstract: Abstract The aim of this study was to considered possible discrepancy in electromagnetic (EM) fascination in the human head. Commercially available software CST Microwave Studio based on the finite-difference time-domain (FDTD) method was adopted in this study. In this calculation, the conductivity and permittivity of all tissues were increased from 10 to 20% except using if not the same revelation conditions. Familiar cellular phone frequencies of 835, 900, and 1900 MHz were investigated in this research. The rise of up to 20% in conductivity, permittivity and varied substrate material always caused a SAR variation of 30.42% for SAR 1 g and 23.75% for SAR 10 g at 835 MHz, variation of 22.41% for SAR 1 g and 21.96% for SAR 10 g at 900 MHz and variation of 11.96% for SAR 1 g and 14.29% for SAR 10 g at 1900 MHz respectively.

Design of a satellite antenna for Malaysia beams by ray tracing method

Abstract: In the implementation of geostationary satellite for various applications such as broadcasting or military, it is essential for spacecraft antenna to provide precise contour beam to effectively serve the required region. Since the Malaysia coverage requires two separate beams to cover the west and east part of the country as shown in Fig.1, precise beam positions and feed positions should be designed.

Performance investigation of a uni-planar compact electromagnetic bandgap (UC-EBG) structure for wide bandgap characteristics

Abstract: A simple uni-planar EBG structure with reduced cell size is proposed for lower frequency band operation. The simulations of the design are performed using finite element method. Directive transmission method is applied to compute the bandgap of the EBG. The compact EBG structure exhibits wide stopband with different type of substrate materials. From the reflection and transmission characteristics the maximum bandgap obtained is 2.57 GHz (56.8%) and the best mutual coupling reduction level is −90 dB. The planar design can be easily fabricate on regular PC board and suitable for wide range of compact applications.

Analysis of mushroom-like EBG structure and UC-EBG for SAR reduction

Abstract: Advances in telecommunications technologies today have led to a wide usage of mobile phones in global community. Nowadays, the mobile phone has become an essential communication tool for everyone. By the end of 2009, the number of mobile phone subscriptions was estimated 5 billion worldwide [1]. This is more than 370 times the number of users in 1990. Since the number of mobile phone users is huge and keep increasing every year, it is crucial to not only study, understand and monitor any potential public health effects from the mobile phone radiation exposures, but also propose an effective method for reducing the Specific Absorption Rate (SAR) to the minimum level.

Effects of electromagnetic absorption toward a human head due to variation of its dielectric properties at 900 and 1900 MHz with different antenna substrates

Abstract: Abstract The aim of this paper is to analyze the effects of electromagnetic (EM) energy absorption at 900 and 1900 MHz when the human head’s dielectric properties are varied. This radiation is measured in terms of specific absorption rate (SAR). The characteristics of the helical antenna and its substrates with variation of the human head dielectric properties were simulated via the finite-difference time domain (FDTD) method using the CST Microwave studio. The human head dielectric properties are manipulated by increasing and decreasing 10% and 20% of each dielectric property. In this study, SAR values increase with increase of the human head’s conductivity, while increase of permittivity and densities decreases it. A helical antenna with a substrate of FR4 resulted in higher SAR values in all frequencies. The head SAR values are higher in the upper frequency exposures. The helical antenna with a substrate of Rogers RO3006 (loss free) was found to be the best-tested substrate, which contributed toward much lower SAR values in all GSM frequency bands.

Dual frequency new shaped microstrip patch antenna for Ku band applications

Abstract: In this paper a compact single feed dual frequency microstrip patch antenna has proposed. Triangular slots are introduced in the three edges of the patch and a small feed line has used another edge of the patch to obtain the dual frequency. The antenna has a condensed structure where patch dimension is about 8.5X7.96X1.905mm3 leading to good bandwidths covering 576 MHz and 540MHz. Across the operating band in lower and higher frequency, stable average peak gain is observed. The radiation patterns are nearly omnidirectional with moderate gain in both the operating frequency. This low profile nature and simple configuration of the proposed antenna show the way to easy fabrication and make it appropriate for the application in wireless and satellite communication.

Design of high performance dual frequency concentric split ring square element for broadband reflectarray antenna

Abstract: ─ An analysis of phase variation and phase range of concentric split ring square element for broadband reflectarray antenna is presented in this paper. This element is the combination of a splitted single square and ring element whereas the square element is the modification of the conventional annular ring in which, instead of using annul as the hole, this new idea presents a square as the hole in the ring. This will modifies the current distribution in the element which will then improve the performance of the bandwidth as the objective of this work. The physical interpretation of the elements is presented and variety of frequency responses pattern is described and analysed. The design procedure and critical parameters consist of phase range and phase slope (or variation) are also discussed. The proposed antenna element effectively covers two frequency operations (13.44 GHz and 18.36 GHz) in Kuband range. Bandwidth broadening is achieved by introducing the ring square combination of element and the practical phase range is achieved through the use of RF35 (thickness = 1.524 mm) as the substrate. The new concept of split initiates to a wider bandwidth (up to 67.6%) for the antenna and can applied to any two frequency operations of Ku-band applications. Index Terms ─ Broader bandwidth, dual frequency, Ku-band, reflectarray antenna.

Improved macro diversity handover in wireless multi-hop relay- networks

Abstract: A method for an improved macro diversity handover (MDHO) for multi-hop relay (MR) networks comprising the steps of maintaining (21) a diversity set for each mobile station (MS) (11) in the handover regions, establishing (22) the topology of the diversity set members, allocating (23) resources to the diversity set members for both first and second phases, notifying (24) the MS of the allocated resource, communicating (25) between the diversity set members and MS during both first and second phases; and combining (26) the signals received during the first and second phase from the diversity set members.

Malaysian Matriculation Student’s Factors in Choosing University and Undergraduate Program

Abstract: The purpose of this study is to identify the influencing factors in selecting a university and course program among Malaysian matriculation students. The study was conducted at two matriculation colleges in south Malaysia. Questionnaire was distributed to students from Negeri Sembilan Matriculation College (NSMC) and Malacca Matriculation College (MMC). These matriculation students are selected because they are in the position of making decision to pursue their studies at tertiary level upon completing the matriculation program. The numbers of students from the matriculation program that pursue to the Malaysia Higher Learning Institutions (HLIs) are comparatively higher than the numbers of students from Malaysia Certificate of Higher Education (MCHE) and diploma program. The study found that the suitability of study program with their personalities, career opportunities and interest were significantly influenced them in choosing the university and course program. Therefore, some strategies and efforts are recommended for the engineering faculty of UKM to acquire better students in the future.

An EBG microstrip antenna for 5.4 GHz WLAN/HIPERLAN applications

Abstract: This study proposed a compact microstrip antenna for 5.4 GHz WLAN/HIPERLAN applications, which achieved a bandwidth of 230 MHz and peak gain of 3.6 dB at 5.4 GHz. The antenna is incorporated with a new electromagnetic bandgap structure that is comprised of a 3×3 array of N-like shape unit. The EBG antenna gives wider bandwidth of 320 MHz, better return loss and improved gain up to 5.46 dB. Enhancement of antenna performances proves the effectiveness of the proposed EBG structure. The design is simulated and analyzed with finite element method based solver HFSS.

Performance evaluation of PAPR in OFDM for UMTS-LTE system

Abstract: Next generation mobile telecommunication networks will provide high data rates needed for multimedia rich applications as the demand in mobile broadband services is expected to increase in the coming years. Orthogonal Frequency Division Multiplexing (OFDM) technique has been increasing its popularity as a transmission scheme for several radio technologies. One of the challenging issues in OFDM technique is its high peak-to-average power ratio (PAPR). This paper studies the performance of PAPR in long term evolution (LTE) of universal mobile telecommunications system (UMTS). The implementation will be based on specifications and protocols from 3rd Generation Partnership Project (3GPP) work groups. The simulator used to simulate UMTS-LTE environment has been developed in Matlab which follows the standard according to UMTS-LTE physical layer transmission scheme. Evaluation results show that reduction of PAPR can be seen in UMTS-LTE model compared to conventional OFDM model.

A new design of split ring resonators for electromagnetic (em) absorption reduction in human head

Abstract: The reducing electromagnetic (EM) absorption reduction with a new type of triangular split ring resonators (TSSRs) based on triangular metamaterials (TMMs) attachment is investigated. The finite-difference time-domain method with lossy-Drude model is adopted in this investigation. The technique of EM absorption reduction is discussed and the effects of position, distance, and size of new design of metamaterials are investigated. Metamaterials have achieved a 63.40% reduction of the initial SAR value for the case of

Design and analysis of a compact planar electromagnetic bandgap (EBG) structure

Abstract: A reduced size planar electromagnetic bandgap structure (EBG) is presented in this study. Method of suspended microstrip line is utilized to examine the transmission characteristics of the EBG and transmission phenomenon are analyzed. The stopband performances of the EBG are also invetigated by varying the dielectric constant and the thickness of the substrate. With the compact geometry a wide band of 17.56 GHz is achieved and the coupling reduction level is around −60 dB. All of the simulated results are presented and discussed. The results validate the effectiveness of the proposed configuration for wide range of applications to improve the system efficiency.

Measured electrical characteristics of an array feed offset parabolic reflector antenna

Abstract: For convenient portable earth stations of satellite communications, offset parabolic reflector antennas are employed in broadcasting TV [1] and military uses [2]. Authors have been developing an array feed offset parabolic reflector antenna [3]. The array feed was designed to improve antenna gain of the reflector antenna [4]. Realization of the array feed was ensured through electromagnetic simulations [5]. In this paper, measured electrical characteristics of a fabricated array feed and the offset parabolic reflector antenna. Through comparisons of measured and calculated results, actual realization of the antenna and effectiveness of radiation pattern synthesis of the array feed are ensured.

Investigation on bandwidth enhancement of dual frequency concentric ring square reflectarray element

Abstract: This paper investigates a new designed element namely concentric element to improve the limited bandwidth of reflectarray element. This element is using single-layer configuration with an introduction of split concept into the element. The dual frequency operation is realized through the using of two elements of ring and ring square at 13.44 GHz and 18.36 GHz. The bandwidth broadening is observed improved from 19.8% to 20.3% in which comparable of solid and split element.

Design of a compact multiband antenna on Al 2 O 3 ceramic material substrate

Abstract: A compact electrically small multiband rectangular shape microstrip patch antenna is designed and analyzed in this paper. The antenna designed with 13 × 10 mm2 radiating copper patch on Aluminium oxide high dielectric ceramic material substrate with ground plane for three different frequency application which is smaller in size compared to other available multiband antennas. The proposed antenna is designed and analyzed by using finite element method 3-D full wave electromagnetic high frequency structure simulator. From the result it is observed that, in 4.7 GHz, 9.05 GHz and 13.2 GHz resonance frequency the impedance bandwidth (VSWR ≤ 2) below −10 dB return loss obtained are 400 MHz, 200 MHz, 800 Mhz and achieved gain are 2.53 dBi, 6.72 dBi, 1.95 dBi respectively.

Analisis pengurangan kadar penyerapan spesifik dalam kepala manusia menggunakan bahan ferit dan metabahan

Abstract: Kertas ini membincangkan kaedah untuk mengurangkan kesan interaksi gelombang elektromagnet dengan kepala manusia menggunakan bahan ferit dan metabahan. Pengukuran pengurangan bagi Kadar Penyerapan Spesifik (SAR) menggunakan bahan ferit dan metabahan telah dilaksana dengan kaedah domain-masa perbezaan-terhingga (FDTD) model Lossy-Drude melalui perisian CST Microwave Studio. Metabahan dibentuk dengan menyusun penyalun cincin terpisah (SRRs) secara berkala. Nilai SAR diukur pada beberapa nilai jarak antara model kepala dengan telefon, kelebaran, ketebalan dan ketinggian bahan ferit dan metabahan. Hasil kajian menunjukkan bahawa nilai SAR1g telah berkurang kepada 1.043 W/kg dengan menggunakan bahan ferit dan 1.161 W/kg dengan menggunakan metabahan. Bagi SAR10g, nilai SAR menurun kepada 0.676 W/kg menggunakan bahan ferit dan 0.737 W/kg dengan menggunakan metabahan. Keputusan bagi nilai SAR dalam kepala manusia dengan kehadiran SRR yang membentuk metabahan telah dianalisis untuk menentusahkan kesan bagi pengurangan SAR ini. Keputusan analisis ini boleh memberikan maklumat yang dapat membantu dalam reka bentuk peralatan komunikasi tanpa wayar bagi mematuhi peraturan keselamatan.