scispace - formally typeset
Search or ask a question

Showing papers in "Progress in Electromagnetics Research-pier in 2009"


Journal ArticleDOI
TL;DR: In this paper, a beam steering technique is realized at the flrst sideband by controlling the switch-on time sequences of each element in the TMLA without using phase shifters.
Abstract: In this paper, a novel technique for electronic beam steering in time modulated linear array (TMLA) is proposed. The beam steering technique is realized at the flrst sideband by controlling the switch-on time sequences of each element in the TMLA without using phase shifters. The difierential evolution (DE) algorithm is employed to improve the gain and suppress the sidelobe levels (SLLs) at both the center frequency and the flrst sideband, simultaneously. An S-band 8-element double-layered printed dipole linear array was used to verify the technique experimentally. Measured results are compared with numerical data, and good agreement is reported. Moreover, some simulation results on the binary phase shift keying (BPSK) modulated signals arriving from difierent directions received by the proposed approach are presented, which validates the application of the proposed beam steering technique.

160 citations


Journal ArticleDOI
TL;DR: A robust and computationally efficient 4D image reconstruction algorithm applied to real ECT data that takes advantage of the temporal correlation between 3D ECT frames to reconstruct movies of dielectric maps.
Abstract: Electrical capacitance tomography (ECT) is a relatively mature non-invasive imaging technique that attempts to map dielectric permittivity of materials. ECT has become a promising monitoring technique in industrial process tomography especially in fast flow visualization. One of the most challenging tasks in further development of ECT for real applications are the computational aspects of the ECT imaging. Recently, 3D ECT has gained interest because of its potential to generate volumetric images. Computation time of image reconstruction in 3D ECT makes it more difficult for real time applications. In this paper we present a robust and computationally efficient 4D image reconstruction algorithm applied to real ECT data. The method takes advantage of the temporal correlation between 3D ECT frames to reconstruct movies of dielectric maps. Image reconstruction results are presented for the proposed algorithms for experimental ECT data of a rapidly moving object.

156 citations


Journal ArticleDOI
TL;DR: In this paper, a single-feed low-profile and easy to fabricate circularly polarized microstrip patch antenna has been developed for GPS applications, where four slots are etched near edges of the patch and a crossed slot etched in the center for generating circular polarization.
Abstract: A single-feed low-profile and easy to fabricate circularly polarized microstrip patch antenna has been developed for GPS applications. For dual frequency operation, four slots are etched near edges of the patch and a crossed slot etched in the center for generating circular polarization. In order to reducing the frequency ratio of two frequency bands of the antenna, the patch is loaded by four short circuit microstrip stubs. The paper reports several simulation results that confirm the desired characteristics of the antenna. Using stub loading, the frequency ratio of two bands of the antenna can be, even, reduced to 1.1.

152 citations


Journal ArticleDOI
TL;DR: In this paper, a novel ultra wideband (UWB) wide slot antenna with via holes is presented for UWB applications, which is composed of a trapezoidal slot on the ground plane, a rectangular patch in the center of the slot and three via holes connecting the rectangular patch and the microstrip feedline.
Abstract: A novel compact ultra-wideband (UWB) wide slot antenna with via holes is presented for UWB applications. The antenna is composed of a trapezoidal slot on the ground plane, a rectangular patch in the center of the slot and three via holes connecting the rectangular patch and the microstrip feed-line. The antenna is successfully designed, implemented, and measured. The measured results show that the proposed antenna with compact size of 27:0mm£29:0mm£1:0mm achieves good performance, such as an impedance matching bandwidth of 111.7% (jS11j • i10dB), constant gain and stable radiation patterns over its whole frequency range.

149 citations


Journal ArticleDOI
TL;DR: Mahatthanajatuphat et al. as mentioned in this paper presented a rhombic patch monopole antenna applied with a technique of fractal geometry to effectively support personal communication system (PCS 1.85-1.99 GHz), universal mobile telecommunication system (UMTS 1.92-2.17 GHz), wireless local area network (WLAN), and mobile worldwide interoperability for microwave access (Mobile WiMAX), which operate in the 2.4 GHz (2.35 GHz/5.85 GHz) bands, and 5.5 GHz (5.2/5
Abstract: This paper presents a rhombic patch monopole antenna applied with a technique of fractal geometry. The antenna has multiband operation in which the generator model, which is an initial model to create a fractal rhombic patch monopole, is inserted at each center side of a rhombic patch monopole antenna. Especially, a modified ground plane has been employed to improve input impedance bandwidth and high frequency radiation performance. The proposed antenna is designed and implemented to effectively support personal communication system (PCS 1.85–1.99 GHz), universal mobile telecommunication system (UMTS 1.92–2.17GHz), wireless local area network (WLAN), which usually operate in the 2.4 GHz (2.4–2.484 GHz) and 5.2/5.8 GHz (5.15–5.35 GHz/5.725–5.825GHz) bands, mobile worldwide interoperability for microwave access (Mobile WiMAX), and WiMAX, which operate in the 2.3/2.5 GHz (2.305– 2.360 GHz/2.5–2.69 GHz) and 5.5 GHz (5.25–5.85 GHz) bands. The radiation patterns of the proposed antennas are similar to an omnidirectional radiation pattern. The properties of the antenna such as return losses, radiation patterns and gain are determined via numerical simulation and measurement. Corresponding author: C. Mahatthanajatuphat (cmp@kmutnb.ac.th). 58 Mahatthanajatuphat et al.

142 citations


Journal ArticleDOI
TL;DR: In this article, a broadband inverted E-H shaped microstrip patch antenna is proposed and experimentally investigated for electromagnetic analysis including the impedance bandwidth, radiation pattern, and antenna gain.
Abstract: A broadband inverted E-H shaped microstrip patch antenna is proposed and experimentally investigated. The antenna employs novel E-H shaped patch with L-probe feed technique. Prototype of the proposed antenna has been fabricated and measured for electromagnetic analysis including the impedance bandwidth, radiation pattern, and antenna gain. The designed antenna has a dimension of 80mm by 50mm, leading to broad bandwidths covering 1.76GHz to 2.38GHz. Stable radiation patterns across the operating bandwidth are observed. In addition, a parametric study is conducted to facilitate the design and optimization process.

129 citations


Journal ArticleDOI
TL;DR: In this article, a compact Vivaldi antenna array printed on a thick substrate and fed by a Substrate Integrated Waveguides (SIW) structure has been developed, which utilizes a compact SIW binary divider to significantly minimize the feed structure insertion losses.
Abstract: A compact Vivaldi antenna array printed on thick substrate and fed by a Substrate Integrated Waveguides (SIW) structure has been developed. The antenna array utilizes a compact SIW binary divider to significantly minimize the feed structure insertion losses. The low-loss SIW binary divider has a common novel Grounded Coplanar Waveguide (GCPW) feed to provide a wideband transition to the SIW and to sustain a good input match while preventing higher order modes excitation. The antenna array was designed, fabricated, and thoroughly investigated. Detailed simulations of the antenna and its feed, in addition to its relevant measurements, will be presented in this paper.

124 citations


Journal ArticleDOI
TL;DR: In this article, the frequency behavior of the multilayer structure comprised of double negative (DNG) and dielectric slabs is presented in detail, which consists of two layers.
Abstract: MULTILAYER SYSTEM OF LORENTZ/DRUDE TYPEMETAMATERIALS WITH DIELECTRIC SLABS AND ITSAPPLICATION TO ELECTROMAGNETIC FILTERSC. SabahPhysikalisches InstituteJohann Wolfgang Goethe UniversityMax-von-Laue-Strasse 1, D-60438, Frankfurt am Main, GermanyS. UckunElectrical and Electronics Engineering DepartmentUniversity of GaziantepGaziantep 27310, TurkeyAbstract—In this work, frequency behavior of the multilayerstructure comprised of double-negative (DNG) and dielectric slabs ispresented in detail. The multilayer structure consists of

119 citations


Journal ArticleDOI
TL;DR: Duan et al. as mentioned in this paper reviewed the research progress in reversed Cherenkov radiation in double-negative metamaterials starting from the first experimental verification of the DNMs reported in 2001, including theories, numerical computation and simulation and experiments.
Abstract: We review the research progress in reversed Cherenkov radiation in double-negative metamaterials (DNMs) starting from the first experimental verification of the DNMs reported in 2001, including theories, numerical computation and simulation and experiments. We also discuss the potential applications to particle detectors and highpower microwave or millimeter-wave devices, including the oscillators and amplifiers, and the formidable challenges needed to be resolved before the benefits of using such artificial materials can be harvested. Corresponding author: Z. Y. Duan (zhyduan@uestc.edu.cn).

115 citations


Journal ArticleDOI
TL;DR: In order to measure the array performance under MIMO signaling conditions a multi-port metric is used to characterize the compact array rather than the scattering matrix characterization, which has low profile, easy fabrication, low cost and good isolation.
Abstract: A novel compact four element multiple input multiple output (MIMO) antenna is proposed. The antenna is composed of four E-shaped patch elements and operates at 5.8 GHz. The single Eshaped patch antenna, operate at this frequency is designed using the Invasive Weed optimization algorithm. This algorithm is then applied to design the selected orthogonal polarization arrangement for two and four element MIMO antenna for high degree of isolation. In order to measure the array performance under MIMO signaling conditions a multi-port metric is used to characterize the compact array rather than the scattering matrix characterization. The designed antennas have low profile, easy fabrication, low cost and good isolation. The simulation and measurement results of reflection coefficient, mutual coupling and radiation pattern are presented.

114 citations


Journal ArticleDOI
TL;DR: In this article, a simple and simple method for calculating the mutual inductance between two non-coaxial circular coils with parallel axes is presented. But it is not suitable for all possible circular coils such as coils of rectangular cross section, thin wall solenoids, thin disk coils (pancakes) and circular filamentary coils.
Abstract: We present a practical and simple method for calculating the mutual inductance between two non-coaxial circular coils with parallel axes. All possible circular coils such as coils of rectangular cross section, thin wall solenoids, thin disk coils (pancakes) and circular filamentary coils are taken into consideration. We use Grover’s formula for the mutual inductance between two filamentary circular coils with parallel axes. The filament method is applied for all coil combinations, for coils of the rectangular cross section and for thin coils. We consider that the proposed method is very simple, accurate and practical for engineering applications. Computed mutual inductance values obtained by the proposed method have been verified by previously published data and the software Fast-Henry. All results are in a very good agreement. This method can be used in various electromagnetic applications such as coil guns, tubular linear motors, transducers, actuators and biomedical implanted sensors.

Journal ArticleDOI
TL;DR: One-dimensional ternary photonic crystals are suggested as refractometric sensing elements, for sensing very small refractive index changes of a medium as discussed by the authors, which are not only remarkably smaller, but are also more sensitive than one-dimensional binary photonic crystal based sensing element.
Abstract: One-dimensional ternary photonic crystals are suggested as refractometric sensing elements, for sensing very small refractive index changes of a medium. These one-dimensional ternary photonic crystals based refractometric sensing elements are not only remarkably smaller, but are also more sensitive than one-dimensional binary photonic crystal based sensing element recently suggested by researchers.

Journal ArticleDOI
TL;DR: The factors afiecting the complexity of the inverse problem are exploited to trace guidelines aimed at setting the matching ∞uid, the frequency range and the number of probes in such a way that the dielectric parameters of female breast tissues can be reliably retrieved.
Abstract: Microwave tomography deserves attention in biomedical imaging, owing to its potential capability of providing a morphological and functional assessment of the inspected tissues. However, such a goal requires the not trivial task of solving a non linear inverse scattering problem. In this paper, the factors afiecting the complexity of the inverse problem are exploited to trace guidelines aimed at setting the matching ∞uid, the frequency range and the number of probes in such a way that the dielectric parameters of female breast tissues can be reliably retrieved. Examples, concerning 2D realistic numerical phantoms obtained by NMR images, are given to asses a posteriori the efiectiveness of the proposed guidelines.

Journal ArticleDOI
TL;DR: This work presents a new indoor localization method based on the fingerprinting technique that uses a ray-tracing model that provides information about multipath effects and calculates the localization estimation while taking into account the Euclidian distance between the DOA and the RSS from each unknown position.
Abstract: This work presents a new indoor localization method based on the fingerprinting technique. The proposed method uses a ray-tracing model that provides information about multipath effects. This information is stored in a dataset during the first stage of the fingerprinting method. The direction of arrival (DOA) and received signal strength (RSS) are used in the fingerprinting technique as a hybrid system. The localization estimation is calculated while taking into account the Euclidian distance between the DOA and the RSS from each unknown position and the information of the fingerprints. Numerical calculations were performed to show the mean and the standard deviation of the estimated error.

Journal ArticleDOI
TL;DR: In this paper, the exact 1-soliton solution of the complex Ginzburg-Landau equation with power law nonlinearity was obtained for the propagation of solitons through nonlinear optical flbers.
Abstract: This paper obtains the exact 1-soliton solution of the complex Ginzburg- Landau equation with power law nonlinearity that governs the propagation of solitons through nonlinear optical flbers. The technique that is used to carry out the integration of this equation is He's semi-inverse variational principle.

Journal ArticleDOI
TL;DR: In this article, a circularly polarized microstrip antenna on a suspended substrate with a coplanar capacitive feed and a slot within the rectangular patch has been proposed, which exhibits a much higher impedance bandwidth of about 49% and also yields return loss better than -15 dB in the useful range of circular polarization.
Abstract: In this paper we propose a circularly polarized (CP) microstrip antenna on a suspended substrate with a coplanar capacitive feed and a slot within the rectangular patch. The antenna has an axial ratio bandwidth (< 3 dB) of 7.1%. The proposed antenna exhibits a much higher impedance bandwidth of about 49% (S11 < -10 dB) and also yields return loss better than -15 dB in the useful range of circular polarization. Measured characteristics of the antenna are in good agreement with the simulated results. The radiation patterns indicate good cross polarization rejection and low back lobe radiations. The design proposed here can be scaled to any frequency of interest.

Journal ArticleDOI
TL;DR: In this article, a new high gain wideband L-probe fed inverted EE-H shaped slotted (LEE-H) microstrip patch antenna is presented in which the antenna exhibits stable radiation pattern in the entire operating band.
Abstract: A new high gain wideband L-probe fed inverted EE-H shaped slotted (LEE-H) microstrip patch antenna is presented in this paper. The design adopts contemporary techniques; L-probe feeding, inverted patch structure with air-fllled dielectric, and EE-H shaped patch. The integration of these techniques leads to a new patch antenna with a low proflle as well as useful operational features, as the broadband and high gain. The measured result showed satisfactory performance with achievable impedance bandwidth of 21.15% at 10dB return loss (VSWR • 2) and a maximum gain of 9.5dBi. The antenna exhibits stable radiation pattern in the entire operating band.

Journal ArticleDOI
TL;DR: In this paper, a hybrid classifier for polarimetric SAR images is proposed, which consists of span image, the H/A/α decomposition, and the gray-level co-occurrence matrix (GLCM) based texture features.
Abstract: This paper proposes a hybrid classifier for polarimetric SAR images. The feature sets consist of span image, the H/A/α decomposition, and the gray-level co-occurrence matrix (GLCM) based texture features. Then, the features are reduced by principle component analysis (PCA). A 3-layer neural network (NN) is constructed, trained by resilient back-propagation (RPROP) method to fasten the training and early stop (ES) method to prevent the overfitting. The results of San Francisco and Flevoland sites compared to Wishart Maximum Likelihood and wavelet-based method demonstrate the validness of our method in terms of confusion matrix and overall accuracy. In addition, NNs with and without PCA are compared. Results show the NN with PCA is more accurate and faster.

Journal ArticleDOI
TL;DR: In this article, a multiband slot antenna with modifying fractal geometry fed by coplanar waveguide (CPW) transmission line is presented, which is designed by modifying an inner fractal patch of the antenna to operate at multiple resonant frequencies, which efiectively supports the digital communication system (DCS 1.71{1.88GHz), worldwide interoperability for microwave access (WiMAX 3.30{3.80GHz), IMT advanced system or forth generation mobile communication system(3.40{4.2GHz), and wireless local area network
Abstract: This paper presents a multiband slot antenna with modifying fractal geometry fed by coplanar waveguide (CPW) transmission line. The presented antenna has been designed by modifying an inner fractal patch of the antenna to operate at multiple resonant frequencies, which efiectively supports the digital communication system (DCS 1.71{1.88GHz), worldwide interoperability for microwave access (WiMAX 3.30{3.80GHz), IMT advanced system or forth generation mobile communication system (3.40{4.2GHz), and wireless local area network (WLAN 5.15{ 5.35GHz). Manifestly, it has been found that the radiation patterns of the presented antenna are still similarly to the bidirectional radiation pattern at all operating frequencies. The properties of the antennas, for instance, return losses, radiation patterns and gain are determined via numerical simulation and measurement.

Journal ArticleDOI
TL;DR: In this paper, a generalized approach to design an electromagnetically coupled microstrip ring antenna for dual-band operation is presented, where a stub is attached to the inner edge of the side opposite to the feed arm to compensate for the losses in electrical length caused by widening.
Abstract: This paper presents a generalized approach to design an electromagnetically coupled microstrip ring antenna for dual-band operation. By widening two opposite sides of a square ring antenna, its fractional bandwidth at the primary resonance mode can be increased significantly so that it may be used for practical applications. By attaching a stub to the inner edge of the side opposite to the feed arm, some of the losses in electrical length caused by widening can be regained. More importantly, this addition also alters the current distribution on the antenna and directs radiations at the second resonant frequency towards boresight. It has also been observed that for the dual frequency configurations studied, the ratio of the resonant frequencies (center dot r(2)center dot center dot r(1)) can range between 1.55 and 2.01. This shows flexibility in designing dual frequency antennas with a desired pair of resonant frequencies.

Journal ArticleDOI
TL;DR: In this article, a new analytical approach is proposed to calculate the magnetic field distribution in coaxial magnetic gears, where a set of partial differential equations in terms of scalar magnetic potential is used to describe the field behavior, and the solution is determined by considering the boundary constraints.
Abstract: Coaxial magnetic gears are a new breed of magnetic devices, which utilize the interaction of permanent magnet fields to enable torque transmission. Apart from using a numerical approach for their magnetic field analysis, an analytical approach is highly desirable since it can provide an insightful knowledge for design and optimization. In this paper, a new analytical approach is proposed to calculate the magnetic field distribution in coaxial magnetic gears. A set of partial differential equations in terms of scalar magnetic potential is used to describe the field behavior, and the solution is determined by considering the boundary constraints. The accuracy of the proposed approach is verified by comparing the field distribution results with those obtained from the finite element method.

Journal ArticleDOI
TL;DR: In this paper, a generalized Wilkinson power divider operating at two arbitrary frequencies with unequal power dividing ratio was proposed to achieve unequal power division and perfect matching at dual-frequency, a novel structure consisted of four dualfrequency transformers in two sections is proposed.
Abstract: In this paper, we propose a generalized Wilkinson power divider operating at two arbitrary frequencies with unequal power dividing ratio. To achieve unequal power division and perfect matching at dual-frequency, a novel structure consisted of four dual-frequency transformers in two sections is proposed. For the compact power divider, the parallel and series RLC structures can be chosen to obtain effective isolation between the two outports according to different frequency ratios. Furthermore, the closed-form design equations of the unequal dual-frequency power divider are derived based on circuit theory and transmission line theory. Finally, simulation and experiment results of two examples including parallel and series RLC structures indicate that all the theoretical features of these unequal power dividers can be fulfilled at dual-frequency simultaneously.

Journal ArticleDOI
TL;DR: In this paper, the authors used the lossy-drude model to reduce the Speciflc Absorption Rate (SAR) with ferrite sheet attachment and showed that the SAR averaging over 10gm was better than that for 1gm and SAR reduction of 57.75% is achieved for SAR 10gm.
Abstract: In this paper, reducing Speciflc Absorption Rate (SAR) with ferrite sheet attachment is investigated. The flnite-difierence time-domain method with Lossy-Drude model is adopted in this study. The methodology of SAR reduction is addressed and then the efiects of attaching location, distance, size and material properties of ferrite sheet on the SAR reduction are investigated. Computational results show that the SAR averaging over 10gm was better than that for 1gm and SAR reduction of 57.75% is achieved for SAR 10gm. These results show the way to choose a ferrite sheet with the maximum SAR reducing efiect for phone model.

Journal ArticleDOI
TL;DR: In this article, the dispersion characteristics of two types of two-dimensional dielectric plasma photonic crystal are studied based on modified plane wave method, and the eigenvalue equations of TM mode of type-1 and type-2 structures are derived respectively; their dispersion curves are confirmed by software simulation.
Abstract: Dispersion characteristics of two types of two-dimension dielectric plasma photonic crystal are studied based on modified plane wave method. Firstly, the eigenvalue equations of TM mode of type-1 and type-2 structures are derived respectively; their dispersion curves are confirmed by the software simulation. Secondly, the influences of normalized plasma frequency, filling factor and relative dielectric constant on photonic band gap, and relative photonic band gap width are analyzed respectively, and some corresponding physical explanations are also given. These results would provide theoretical instructions for designing new photonic crystal devices using plasma- dielectric structure.

Journal ArticleDOI
TL;DR: In this article, a series of curved microstrip antennae with defected ground structure for multiband is proposed, which are more smaller, conveniently conformal, wider radiation beam and suitable for WLAN terminal for difierent environment.
Abstract: A series of curved microstrip antennae with defected ground structure for multiband are proposed, which are more smaller, conveniently conformal, wider radiation beam and suitable for WLAN terminal for difierent environment. The relation between the main geometry parameters and the antennas' characters are studied with the cavity model method and EM simulation, and the optimum size antenna is achieved later. If keeping the other parameters but increasing the curving angle fi, the return loss is almost good at f = 2:45GHz, but poor at f = 5:25GHz and 5.8GHz. After slight tuning the key parameters, these curved antennae all can work at f = 2:45GHz, 5.25GHz and 5.8GHz, and their patterns in the plane that is vertical to the curve axes become more wider or even omni- directional with the curving angle fi increasing, which are verifled by experiment, their measured gain are 2dB{6.3dB.

Journal ArticleDOI
TL;DR: In this paper, the radial component of the magnetic fleld produced by a ring permanent magnet whose polarization is radial can be expressed in terms of elliptic integrals, which is useful for optimization purposes.
Abstract: This paper presents some improved analytical expressions of the magnetic fleld produced by arc-shaped permanent magnets whose polarization is radial with the amperian current model. First, we show that the radial component of the magnetic fleld produced by a ring permanent magnet whose polarization is radial can be expressed in terms of elliptic integrals. Such an expression is useful for optimization purposes. We also present a semi-analytical expression of the axial component produced by the same conflguration. For this component, we discuss the terms that are di-cult to integrate analytically and compare our expression with the one established by Furlani (1). In the second part of this paper, we use the amperian current model for calculating the magnetic fleld produced by a tile permanent magnet radially magnetized. This method was in fact still employed by Furlani for calculating the magnetic fleld produced by radially polarized cylinders. We show that it is possible to obtain a fully analytical expression of the radial component based on elliptic integrals. In addition, we show that the amperian current model allows us to obtain a fully analytical expression of the azimuthal component. All the expressions determined in this paper are compared with the ones established by Furlani (1) or in previous works carried out by the authors.

Journal ArticleDOI
TL;DR: In this paper, a time stepping two-dimensional FEM is performed for modeling and analysis of a IM with insulation failure inter-turn fault FEM analysis is used for magnetic fleld calculation and the magnetic ∞ux density and vector potential of machine is obtained for healthy and faulty cases.
Abstract: In this paper, a time stepping two-dimensional FEM is performed for modeling and analysis of a IM with insulation failure inter-turn fault FEM analysis is used for magnetic fleld calculation and the magnetic ∞ux density and vector potential of machine is obtained for healthy and faulty cases Comparing the magnetic ∞ux distribution of healthy and faulty machines helps to detect the in∞uence of turn fault The machine parameters (self and mutual inductances) are obtained for IM with inter-turn fault Finally, the FEM machine model is used for studying the machine under difierent fault condition Study results including phases and fault currents express the behavior of machine with inter-turn faults The symmetrical current components of IM with difierent fault severity are obtained by FE study and studied The machine torque in healthy and faulty condition is also obtained and compared The torque vibration increase upon to degree of fault

Journal ArticleDOI
TL;DR: HuHu et al. as discussed by the authors proposed a compact dual-band annular-ring slot antenna (ARSA) for use in 2.4/5GHz wireless local-area networks (WLANs).
Abstract: COMPACT DUAL-BAND ANNULAR-RING SLOTANTENNA WITH MEANDERED GROUNDED STRIPJ.-Y. SzeDepartment of Electrical and Electronic EngineeringChung Cheng Institute of TechnologyNational Defense University190 Sanyuan 1st. St., Dasi Township, Taoyuan County 33508, Taiwan,R.O.C.T.-H. Hu and T.-J. ChenDepartment of Electrical EngineeringDayeh University168 University Rd., Dacun, Changhua County 51591, Taiwan, R.O.C.Abstract|A compact dual-band annular-ring slot antenna (ARSA) isproposed for use in 2.4/5GHz wireless local-area networks (WLANs).With a meandered grounded strip embedded in the ring slot, threeresonant modes were excited. With a pair of notches properly etchedin the inner circular patch, the third resonant band was su–cientlylowered so that the second and third resonant bands are combinedto form a wider upper operating band. If scaled to the same loweroperating-band center frequency, the proposed ARSA measures only53.6% the area of a conventional microstrip-line-fed ARSA. Measuredand simulated results were found to agree reasonably well with eachother.1. INTRODUCTIONDue to the advantages of large impedance bandwidths and low proflles,printed slot antennas (PSAs) have received much attention in recentyears. Some PSAs were designed to generate circularly polarizedwaves with desired handed senses [1{3]; some were further enhancedin their bandwidths [4{6]; others were developed to support dual-band operations [7{17]. For those microstrip-line-fed PSAs designedfor dual-band operations, many of them are designed to cover the

Journal ArticleDOI
TL;DR: In this article, a triple-mode hexagonal bandpass fllter with capacitive loading stubs is introduced, which adds an open capacitive stub to enlarge the equivalent self capacitance of the resonator, which declines its resonant frequencies.
Abstract: A novel triple-mode hexagonal bandpass fllter with capacitive loading stubs is introduced in this article. The technique, adding an open capacitive stub, is applied to enlarge the equivalent self- capacitance of the resonator, which declines its resonant frequencies. Three radial-line stubs in the center of top layer are used to implement this technique. One mode resonant frequency is varied with the radii of three radial-line stubs, while the other two modes are nearly not afiected. This fllter has a pair of transmission zeros which are close to the passband, thus it behaves with high selectivity. For method validation, a bandpass fllter operating at 2.4GHz is fabricated and measured. The experimental results are demonstrated and discussed.

Journal ArticleDOI
TL;DR: In this paper, a new and fast method is proposed for calculation of the magnetic forces between planar spiral coils by having the external dimension of coils and their number of turns, the force between them at different distances and with different currents can be calculated.
Abstract: Due to the special structure of current carrying planar spiral coils, precise calculation of the forces between them is complicated and time-consuming. To overcome these problems, in this paper a new and fast method is proposed for calculation of the magnetic forces between planar spiral coils. The advantage of the proposed method is that just by having the external dimension of coils and their number of turns, the force between them at difierent distances and with difierent currents can be calculated. The results obtained by direct and proposed calculation methods show the e-ciency of the latter in simplicity and calculation time. The precision of the proposed method has been conflrmed by experimental tests done on constructed coils.