Showing papers by "Norbahiah Misran published in 2011"
TL;DR: In this article, a compact microstrip line-fed ultrawideband (UWB) tapered-shape slot antenna is presented, which is fabricated onto an inexpensive FR4 substrate with an overall dimension of 22 × 24 mm2.
Abstract: A compact microstrip line-fed ultrawideband (UWB) tapered-shape slot antenna is presented. The proposed antenna comprises a tapered-shape slot and rectangular tuning stub. The antenna is fabricated onto an inexpensive FR4 substrate with an overall dimension of 22 × 24 mm2. The experiment shows that the proposed antenna achieves good impedance matching constant gain, stable radiation patterns over an operating bandwidth of 3-11.2 GHz (115.5%) that covers the entire UWB. The nearly stable radiation pattern with a maximum gain of 5.4 dBi makes the proposed antenna suitable for being used in UWB communication applications.
239 citations
TL;DR: In this paper, the authors proposed a compact wideband dual-frequency microstrip antenna with an ofiset microstrip-fed line and a strip close to the radiating edges in the circular slot patch.
Abstract: A compact wideband dual-frequency microstrip antenna is proposed in this paper. By employing an ofiset microstrip-fed line and a strip close to the radiating edges in the circular slot patch, an antenna operating at dual frequency with the impedance bandwidth of 26.2% and 22.2% respectively is presented. By attaching a strip to the radiating edges opposite to the microstrip-fed line, this alters the current distribution and radiation on the antenna at the second resonant frequency. The second frequency is also tunable by varying the lengths of the microstrip-fed line. It is demonstrated that the proposed antenna covers the widebands of UHF and microwave for RFID application. A good agreement is obtained between the simulated and experimental results.
107 citations
TL;DR: In this paper, a double-sided printed compact antenna for UWB application is proposed, having a total size of 30×22 mm, consisting of a patch fed by a microstrip line and a partial ground plane.
Abstract: A double-sided printed compact antenna for UWB application is proposed. The proposed antenna, having a total size of 30×22 mm, consists of a patch fed by a microstrip line and a partial ground plane. The modified ground plane with triangular shaped slots on its top edge helps to increase the bandwidth of the proposed antenna. The double-sided printed antenna has a bandwidth (VSWR≤2) from 3.08 to 15.90 GHz and a maximum gain of 5.9 dBi. Antenna radiation patterns show stable variation within its operating band.
93 citations
TL;DR: In this paper, the authors investigated the effect of attaching metamaterials, perfect electric conductor, and materials on the specific absorption rate reduction in the case of a single phone model.
Abstract: The reducing specific absorption rate with metamaterials attachment is investigated in this article. The finite-difference time-domain method with a lossy-Drude model is adopted in this analysis. The technique of specific absorption rate reduction is discussed, and the effects of attaching location, distance, and size of metamaterials, perfect electric conductor, and materials on the specific absorption rate reduction are investigated. Metamaterials have achieved a 42.12% reduction of the initial specific absorption rate value for the case of 1 gm specific absorption rate and 53.94% reduction for the cases of 10 gm specific absorption rate. These results suggest a guideline to choose various types of metamaterials with the maximum specific absorption rate reducing effect for a phone model.
62 citations
TL;DR: In this paper, a planar antenna with a multi-slotted ground plane was proposed for UWB applications and the measured results showed that the proposed antenna achieves a bandwidth (VSWR ≤ 2) ranges from 2.57 to 16.72 GHz.
Abstract: A planar antenna with a multi-slotted ground plane has been proposed for UWB applications. The compact antenna having a total size of 30 × 22 mm2 consists of a square patch and a partial ground plane. The rectangular slots on the top side of the ground plane help to increase the bandwidth. The measured result shows that the proposed antenna achieves a bandwidth (VSWR ≤ 2) ranges from 2.57 to 16.72 GHz. Details of the proposed antenna and measured results are presented and discussed. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:966–968, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25950
61 citations
TL;DR: In this article, the authors investigated the ionospheric variations before some large earthquakes that occurred during 2004-2007 in Sumatra using GPS and CHAMP data and found that positive and negative anomalies detected within a few hours to 6 days before the earthquakes mostly occur during the daytime hours between 4 and 17 LT.
Abstract: . The paper investigates the ionospheric variations before some large earthquakes that occurred during 2004–2007 in Sumatra using GPS and CHAMP data. The TEC shows the occurrence of positive and negative anomalies detected within a few hours to 6 days before the earthquakes. These anomalies mostly occur during the daytime hours between 4 and 17 LT. The TEC anomalies are mostly consistent with the CHAMP satellite electron density data. The electron density analysis over the 28 March 2005 earthquake epicenter shows that an equatorial anomaly modification took place a few days before the event. The modification took shape in the form of crest amplification during the daytime. The comparison between the TEC and electron density measurements during very quiet geomagnetic conditions is shown to be a useful indicator of a forthcoming earthquake.
49 citations
Journal Article•
TL;DR: In this paper, a dual polarized microstrip patch antenna is proposed for Ku-band applications and the antenna has a compact structure and the total size is 15 mm × 15 mm.
Abstract: A dual polarized microstrip patch antenna is proposed for Ku-band applications. The corner chopped square patch with four bent slots is adopted in this design. The antenna has a compact structure and the total size is 15 mm × 15 mm. The result shows that the impedance bandwidth (VSWR ≤ 2) of the proposed antenna is 950 MHz (7.76%). The antenna with reduced size is also able to achieve the stable radiation performance with a maximum gain of 7.6 dBi in the operating band of 11.76 GHz to 12.71 GHz and the gain variation is about 0.8 dBi. The present design provides a maximum of -26 dB isolation level between the two ports and a stable low cross polarization level for both Eand H-planes. Details of the proposed antenna design and results are presented and discussed. The patch shows a high matching level in Ku-band and isolation elements that makes it suitable for wireless and satellite communication. Dvojno polarizirana mikrostrip antena za Ku-frekvenčni pas Kjučne besede: dvojna polarizacija, mikrotrakasta antena, Ku-frekvenčni pas, visoka izolacija Izvleček: V prispevku opišemo mikrotrakasto anteno z dvojno polarizacijo za uporabo na Ku-frekvenčnem pasu. Antena ima kompaktno strukturo in je velika 15 mm x 15 mm. Rezultati kažejo pasovno širino ( VSWR ≤ 2) 950 MHz (7.76%). Tako zmanjšana antena zmore stabilno sevanje z maksimalno ojačitvijo 7.6 dBi znotraj pasovne širine med 11.76 GHz do 12.71 GHz in stabilnostjo ojačitve znotraj 0.8 dBi. Trenutna zasnova omogoča maksimalno izolacijo med stopnjama -26dB in stabilno nizko križno polarizacijo med E in H ravnijo. V članku so opisane podrobnosti in rezultati predlagane zasnove antene.
45 citations
TL;DR: Numerical results concerning the SAR values in the muscle cube in the presence of resonators exhibit significant SAR reduction, which can provide useful information when designing safety-compliant mobile communication equipment.
44 citations
TL;DR: In this paper, a dual-frequency microstrip antenna is achieved by embedding two parallel slots to the radiating edges and insetting slits at the non-radiating edges.
Abstract: A novel compact dual-frequency microstrip antenna is achieved by embedding two parallel slots to the radiating edges and insetting slits at the non-radiating edges. The proposed antenna exhibits dual-frequency band behavior operating at 867 MHz and 2.45 GHz suitable for UHF and microwave RFID application. The slot loading effect has been studied and evaluated. The two desired frequencies are tunable with frequency ratio of 2.66 to 2.95 by varying the meandered slit length. A good agreement is obtained between the simulated results and experimental results.
43 citations
Journal Article•
41 citations
TL;DR: In this article, the specific absorption rate (SAR) reduction in a muscle cube by using metamaterial was evaluated in a realistic anatomically based model of the muscle cube.
Abstract: The aim of this paper is to evaluate the specific absorption rate (SAR) reduction in a muscle cube by using metamaterial. To evaluate the SAR in a realistic anatomically based model of the muscle cube, the finite-difference time-domain (FDTD) method has been utilized. The effective medium parameter is obtained to be negative at 900 MHz and 1800 MHz band by designing structural parameter of split ring resonators. The reduction is about 44.73% for 900 MHz, and about 48.27% for 1800 MHz was observed in this paper.
Journal Article•
TL;DR: In this article, a planar antenna for broadband applications has been proposed, which consists of a rectangular patch, a partial ground plane and a slot on the ground plane, and the total size is 14.75 × 14.5mm.
Abstract: In this paper, a planar antenna for broadband applications has been proposed. The antenna consists of a rectangular patch, a partial ground plane and a slot on the ground plane. The proposed antenna is easy to be integrated with microwave circuitry for low manufacturing cost. The flat type antenna has a compact structure and the total size is 14.75 ×14.5mm. The result shows that the impedance bandwidth (VSWR ≤ 2) of the proposed antenna is 12.87 GHz (3.02 to 15.89 GHz), which is equivalent to 136.12%. Details of the proposed compact planar UWB antenna design is presented and discussed.
01 Jan 2011
TL;DR: In this paper, the authors presented a compact wideband antenna with partially radiating coplanar ground plane, which shows a wide bandwidth (VSWR ≤ 2) of 92% (from 3.53GHz to 9.5GHz).
Abstract: Many of today's portable communication applications require antennas that are compact, broadband, and easily integrable in a big variety of terminal geometries. This paper presents a compact wideband antenna with partially radiating coplanar ground plane. The prototype of the antenna shows a wide bandwidth (VSWR ≤ 2) of 92% (from 3.53GHz to 9.5GHz). The antenna also exhibits maximum gain of 3.5dBi and stable radiation patterns over the whole bandwidth. Nevertheless, in this paper the significance of the ground planes on the operating bandwidth are examined with the help of current distribution and discussed in detail with supporting parametric analysis.
Journal Article•
Journal Article•
TL;DR: Results suggest that the patch antenna may be the structure of choice when considering safety standards, as its radiation yields the lowest local SAR in the head tissues.
Abstract: In this paper, a comparative study of several antennas commonly used in portable telephones is investigated. These include a monopole, a helix, a patch and a PIFA antenna. Each one of these structures is modeled and numerically tested using finite-difference time-domain (FDTD) method by using CST Microwave Studio. The testing procedure involves antenna simulation in the proximity of the human head and hand. The behavior of each antenna is evaluated for variable distances from the head geometry (0 - 20 mm). The simulation outputs used as measures for this comparative study include the specific absorption rate (SAR). The computed SAR levels within each of the considered tissues vary for the four antennas under investigation and are within the determined health safety standards. Results suggest that the patch antenna may be the structure of choice when considering safety standards, as its radiation yields the lowest local SAR in the head tissues.
TL;DR: In this article, a tri-band RFID antenna consisting of a monopole like bent arm with a capacitively coupled small patch, printed on the alternative side of the ground plane, is presented.
Abstract: A novel compact microstrip antenna is presented for tri-band RFID applications.The antenna consisting of a monopole like bent arm with a capacitively coupled small patch, printed on the alternative side of the ground plane, which might be common for multi-layer reader circuitry. By adjusting the dimension of the bent arm as well as the embedded bent and capacitive coupling, tri-band antenna has obtained in a small profile. The prototyped antenna shows broad impedance bandwidths (10 dB ≤ return loss) of 17.5, 32.7, and 25.5% accordingly in UHF (902-928MHz), 2.45GHz and 5.8GHz RFID bands with stable radiation characteristics.
TL;DR: In this paper, the performance of a free-space optical terrestrial system using on-off keying in the presence of scattering and absorption due to atmospheric gas molecules and aerosols, and pointing error phenomenon due to the link missalignment was evaluated.
Abstract: Performance analysis has been carried out to evaluate the performance of a free-space optical terrestrial system using on-off keying in the presence of scattering and absorption due to atmospheric gas molecules and aerosols, and pointing error phenomenon due to the link missalignment. It is found that in order to achieve a bit error rate (BER) of 10 −9 at a visibility of 1.9 km, a 13.2 dB power penalty is incurred for atmospheric channel in haze condition and for atmospheric channel in rain condition, a heavy rainfall rate of 25 mm/h produces a high atmospheric attenuation coefficient α, and thus almost 18 dB power penalty is induced to achieve a BER of 10 −9 . However, for the atmospheric channel in a fog condition, the visibility can reach 1.1 km and induces a power penalty of 25 dB to maintain the BER of 10 −9 . The power penalty increases when the visibility is reduced, rainfall intensity increased, and an additional power penalty of more than 25 dB is incurred in the presence of pointing error for atmospheric channel of 1.3 km visibility in a light fog condition compared to clear weather condition. C 2011 Society of Photo-Optical Instrumentation Engineers
12 Jul 2011
TL;DR: In this article, a dual-band circularly polarized antenna with small frequency ratio was proposed for Global Positioning System (GPS) applications covering L 1 and L 2 frequencies of 1.575GHz and 1.227GHz, respectively.
Abstract: A new high gain dual-band circularly polarized with a small frequency ratio is proposed for Global Positioning System (GPS) applications covering L1 and L2 frequencies of 1.575GHz and 1.227GHz. The antenna is consists of I slotted compact microstrip antenna with two truncated corners square patches that overlapped without an air-gap. The overall antenna size is 0.315λ 0 × 0.309λ 0 × 0.016λ 0 at 1.227GHz and 0.302λ 0 × 0.302λ 0 × 0.016λ 0 at 1.575GHz (where λ 0 corresponding to center frequency). The design achieved an impedance bandwidth of 20 MHz from 1.22 GHz to 1.24 GHz for the lower band, while upper band covers 97.88 MHz (from 1.562 to 1.66 GHz) with maximum gain of 7.27dBi and 6.87dBi in the lower and upper frequency band respectively. The bandwidth (VSWR ≤ 2) is 1.57% (1.222 GHz to 1.2414 GHz) for L2 and 6.27% (1.5617 GHz to 1.6626 GHz) for L1. The details of the antenna design are shown, and the results with low-profile characteristics make the antenna suitable for GPS applications.
TL;DR: An interpolation prediction method (IPM) has been proposed to predict the propagated signal and to make the ray-tracing algorithm faster, accurate, and simple.
Abstract: A 3D ray tracing simulator has been developed for indoor wireless networks. The simulator uses geometrical optics (GOs) to propagate the electromagnetic waves inside the buildings. The prediction technique takes into account multiple reflections and transmissions of the propagated waves. An interpolation prediction method (IPM) has been proposed to predict the propagated signal and to make the ray-tracing algorithm faster, accurate, and simple. The measurements have been achieved by using a single Wi-Fi network access point as a transmitter and a laptop as a receiver. Measured data had been collected at different positions in indoor environment and compared with predicted signals. The comparison of the predicted and measured received signals gave root mean square error of 2.96 dB and std. deviation of 2.98 dB.
Journal Article•
TL;DR: In this article, the reduction of specific absorption rate (SAR) with shielding material is performed by the finite-difference time-domain method (FDTD) with lossy-Drude model by CST Microwave Studio.
Abstract: This paper proposes the reduction of specific absorption rate (SAR) with shielding material is performed by the finite-difference time-domain method (FDTD) with lossy-Drude model by CST Microwave Studio. We propose SAR evaluation and reduction methods based on power conservation. It has been shown that even though the use of shielding (ferrite) material not only reduces the SAR in the human head but also the radiated power, it reduces the SAR in head more considerably than the radiated power. Shielding materials have achieved a 58.68% reduction of the initial SAR value for the case of 1 gm SAR. These results suggest a guideline to choose various types of materials with the maximum SAR reducing effect for a phone model.
07 Mar 2011
TL;DR: In this article, the design and results of an offset feed UWB antenna with a multiple-slotted ground plane are presented, where the antenna consists of a square shaped radiator, a feed slightly offset from the middle along the radiator side and a ground plane with multiple rectangular slots.
Abstract: This paper presents the design and results of an offset feed Ultrawideband(UWB) antenna with a multiple-slotted ground plane. The antenna consists of a square shaped radiator, a feed slightly offset from the middle along the radiator side and a ground plane with multiple rectangular slots. Simulation results show that the antenna can achieve a wide bandwidth from 3.3 to 18 GHz.
12 Jul 2011
TL;DR: It can be concluded from this studies that the bandwidth can be pronounced improved by using the split concept into the element for giving significant improvement to the performance of linear phase range, phase slope and inevitable bandwidth.
Abstract: This paper presents an investigation of bandwidth enhancement of a concentric split ring square reflectarray element in terms of phase and return loss versus frequency graph performance. The performance of element's phase response is then to be compared to the concentric solid ring square element whereby studies on the phase range and slope are carried out to the variation size of elements within the range 2.63 mm to 4.49 mm. The bandwidth of unit cell element is observed and it has been shown the enhancement of up to 40.7% and 0.5% at dual frequency operation. It can be concluded from this studies that the bandwidth can be pronounced improved by using the split concept into the element for giving significant improvement to the performance of linear phase range, phase slope and inevitable bandwidth. The analysis is executed using the CST Microwave Studio software.
TL;DR: In this paper, a new type of mobile handset antenna structure was designed to reduce the specific absorption rate (SAR) in human head by placing antenna at different position to determine position that are more suitable and effectively reduced the SAR level.
Abstract: We intend and design a new type of mobile handset antenna structure to reduce the specific absorption rate (SAR) in human head. The designed of low SAR handset antenna will be operating at 2.4 GHz frequency for wireless local area network (WLAN) by considering some parameters that determine the performance of the antenna. The authors carried out simulation by placing antenna at different position to determine position that are more suitable and effectively reduced the SAR level. The numerical results are compared and analyzed. The designed antenna operating at the range of frequency from 2373 to 2435 MHz with 2.6% bandwidth (BW) and the radiation pattern is omni-directional. The handset antenna design has achieved 1.483 W/kg for 1 gm SAR and 1.192 W/kg for 10 gm SAR which has been reduced for about 25.75% for 1 gm and 25.50% for 10 gm SAR value of the standard SAR level.
Key words: Finite-difference time-domain (FDTD) method, patch antenna, specific absorption rate (SAR), symmetry.
TL;DR: A topology-aware MDHO technique for time division duplex-orthogonal frequency division multiple access-based interference-limited multi-hop cellular networks and results show that the proposed MDHO significantly outperforms the conventional MDHO.
Abstract: Macro diversity handover (MDHO) is the process by which a mobile station (MS) maintains connection with two or more access stations called a diversity set. In this study, the authors propose a topology-aware MDHO technique for time division duplex (TDD)-orthogonal frequency division multiple access (OFDMA)-based interference-limited multi-hop cellular networks. The proposed MDHO receives all the data signals transmitted by the diversity set members of the MS. It ensures that the topology of the diversity set members is always fully exploited. The efficiency of the proposed MDHO is validated using a mathematical model and computer simulation. The performance evaluation is carried out for different relay station (RS) transmitted powers. Evaluation results show that the proposed MDHO significantly outperforms the conventional MDHO. Over the MDHO regions in which the diversity set members are multi-hop relay base station (MR-BS) and RS, the proposed MDHO offers a carrier to interference and noise ratio gain and a spectral efficiency gain of as much as 4.5 dB and 0.85 bps/Hz, respectively, compared to the conventional MDHO.
12 Jul 2011
TL;DR: The results of using fuzzy Logic technique show that location management cost reduction using Fuzzy logic in cellular radio network using fuzzy logic is decreased about 2% and outperforms the conventional mechanism.
Abstract: In cellular network, mobility management has allowed mobile subscribers to move freely across different networks while maintaining its quality of service for a variety of applications. Location management is one of the main tasks of mobility management. The location management cost depends mainly on subscribers' mobility behavior and its performance which is typically measured by the number of location update performed and the number of cells paged. The objective of this research is to propose, validate and evaluate the performance of location update scheme using fuzzy logic technique for cellular radio system. Three metrics: speed, user density and residence time are proposed and used for fuzzy evaluation. The results of using fuzzy logic technique show that location management cost reduction using Fuzzy logic in cellular radio network using fuzzy logic is decreased about 2% and outperforms the conventional mechanism.
12 Jul 2011
TL;DR: In this paper, a planar monopole antenna with dual band-notch characteristics is proposed for ultrawideband (UWB) communication applications, which consists of an annular ring patch and a partial ground plane with a rectangular slot.
Abstract: A compact planar monopole antenna with dual band-notch characteristics is proposed for ultrawideband (UWB) communication applications. The proposed compact antenna consists of an annular ring patch and a partial ground plane with a rectangular slot. Two partial and semicircular annular slots are etched at the upper and lower side of the ring radiator for achieving dual notched frequency band. The proposed antenna has two stop-bands of 3.2 to 3.6 GHz and 5.05 to 6.08 GHz while maintaining the wideband performance from 3 to more than 11 GHz. A symmetric radiation pattern and stable gain except in the notched band makes the proposed antenna suitable for being used in UWB applications.
Journal Article•
TL;DR: In this article, an annular ring slot microstrip antenna with two pie-shaped circular sectors is presented, which achieves three different operating bands: 190 MHz (0.88 to 1.07 GHz), 1.79 to 3.62 GHz and 880 MHz (5.05 to 5.93 GHz).
Abstract: Wideband and multi-band antennas have become part-and-parcel of modern telecommunication systems. In this article, an annular ring slot microstrip antenna loaded with two pie-shaped circular sectors is presented. With the use of pie-shaped circular sectors along the microstrip feed line, a multi-wider-band operation than for a conventional annular ring slot can be realized. By selecting proper dimensions of the circular sectors, the antenna typically provides three main operating bands and is capable of multi-frequency operations in various personal and wireless applications. From experimental results, with a VSWR ≤ 2, the antenna achieves three wide bandwidths of 190 MHz (0.88 to 1.07 GHz), 1.83 GHz (1.79 to 3.62 GHz) and 880 MHz (5.05 to 5.93 GHz), which are equivalent to impedance bandwidth of 19.5, 67.7 and 16.03 percent, respectively.
TL;DR: In this article, a finite-difference time-domain method with lossy-drude model is adopted to reduce specific absorption rate (SAR) with materials and metamaterials attachment.
Abstract: In this paper, reducing of specific absorption rate (SAR) with materials and metamaterials attachment is investigated. The finite-difference time-domain method with lossy-Drude model is adopted in this study. The methodology of SAR reduction is addressed and the belongings of attaching position, distance, and size of ferrite sheet material properties, perfect electric conductor (PEC), and metamaterials on the SAR reduction are investigated. Materials have achieved a 47.02% reduction of the initial SAR value while metamaterials achieved a reduction of 49.21% respectively for the case of 1 g SAR. These results propose a guideline to decide assorted types of materials and metamaterials with the utmost SAR reducing effect for a phone model.
Key words: Antenna, human head model, lossy-Drude model, materials, metamaterials, specific absorption rate (SAR), symmetry.
01 Dec 2011
TL;DR: In this paper, a planar ultra-wideband antenna with dual band-notched antenna is proposed, which consists of a rectangular radiating patch and a modified partial ground plane.
Abstract: A compact printed planar ultra-wideband antenna with dual band-notched is proposed. The proposed antenna consists of a rectangular radiating patch and a modified partial ground plane. Two rectangular parasitic strips are placed below the substrate to achieve dual band-notched characteristics. The measured results show that the proposed antenna achieved a wide impedance bandwidth from 2.87 to more than 11 GHz, defined by −10 dB return loss with one notch frequency band at 3.3 to 3.8 GHz and the other at 5.1 to 5.6 GHz. Compared to the other designs, the proposed antenna has a simple structure to achieve the notch-band characteristics to reduce the potential interference between UWB and existing WiMAX and WLAN systems. A stable radiation pattern and flat gain except in the notched bands makes the proposed antenna suitable for being used in UWB applications.
01 Oct 2011
TL;DR: Evaluation results show that system using adaptive modulation and coding (AMC) significantly outperforms systems using fixed modulation (FM) and adaptive modulation (AM) schemes alone in terms of the spectral efficiency and percentage of successful links.
Abstract: Mobile WiMAX technology is based on IEEE 80216e standard and considered as one of the most prominent solutions capable to provide high speed access in metropolitan areas Due to limited radio resources, it is necessary to consider radio resource efficiency This paper investigates the spectral efficiency gain achieved when applying link adaptation techniques on the downlink (DL) of the IEEE 80216e-based mobile WiMAX networks The performance evaluation is carried out using a system-level simulation Evaluation results show that system using adaptive modulation and coding (AMC) significantly outperforms systems using fixed modulation (FM) and adaptive modulation (AM) schemes alone in terms of the spectral efficiency and percentage of successful links